From 8a7dfa0972c83fd811a4296e7373574bea4a28d0 Mon Sep 17 00:00:00 2001
From: Nguyễn Gia Phong <mcsinyx@disroot.org>
Date: Sun, 19 Jul 2020 20:34:40 +0700
Subject: [usth/ICT2.7] Remove Udacity transcribes

---
 .../1 - Lesson Overview - lang_en_vs4.srt          |  31 --
 .../10 - Choosing a Pattern - lang_en_vs5.srt      |  95 ----
 .../11 - Choosing a Pattern Quiz - lang_en_vs4.srt |  31 --
 ...osing a Pattern Quiz Solution - lang_en_vs4.srt |  79 ----
 ...13 - Negative Design Patterns - lang_en_vs4.srt |  51 --
 ... - History of Design Patterns - lang_en_vs6.srt | 179 --------
 .../3 - Patterns Catalogue - lang_en_vs4.srt       |  79 ----
 .../4 - Pattern Format - lang_en_vs5.srt           |  71 ---
 .../5 - Factory Method Pattern - lang_en_vs5.srt   | 179 --------
 ...actory Method Pattern Example - lang_en_vs5.srt | 127 -----
 .../7 - Strategy Pattern - lang_en_vs5.srt         | 143 ------
 ...rategy Pattern Example & Demo - lang_en_vs5.srt | 511 ---------------------
 .../9 - Other Common Patterns - lang_en_vs5.srt    | 295 ------------
 13 files changed, 1871 deletions(-)
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/1 - Lesson Overview - lang_en_vs4.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/10 - Choosing a Pattern - lang_en_vs5.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/11 - Choosing a Pattern Quiz - lang_en_vs4.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/12 - Choosing a Pattern Quiz Solution - lang_en_vs4.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/13 - Negative Design Patterns - lang_en_vs4.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/2 - History of Design Patterns - lang_en_vs6.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/3 - Patterns Catalogue - lang_en_vs4.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/4 - Pattern Format - lang_en_vs5.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/5 - Factory Method Pattern - lang_en_vs5.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/6 - Factory Method Pattern Example - lang_en_vs5.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/7 - Strategy Pattern - lang_en_vs5.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/8 - Strategy Pattern Example & Demo - lang_en_vs5.srt
 delete mode 100644 usth/ICT2.7/P3L3 Design Patterns Subtitles/9 - Other Common Patterns - lang_en_vs5.srt

(limited to 'usth/ICT2.7/P3L3 Design Patterns Subtitles')

diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/1 - Lesson Overview - lang_en_vs4.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/1 - Lesson Overview - lang_en_vs4.srt
deleted file mode 100644
index 152b961..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/1 - Lesson Overview - lang_en_vs4.srt	
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@@ -1,31 +0,0 @@
-1
-00:00:00,230 --> 00:00:04,560
-In the last lesson, we talked about design, and we saw how difficult it can
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-be to come up with a good and effective design for a given software system. To
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-00:00:10,010 --> 00:00:12,620
-help address these difficulties, we will discuss
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-design patterns, which can support design activities by
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-5
-00:00:16,560 --> 00:00:20,710
-providing general, reusable solutions to commonly occurring design
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-problems. Similar to architectural styles, design patterns can
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-help developers build better designed systems by reusing design solutions that
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-worked well in the past and by building on those solutions.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/10 - Choosing a Pattern - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/10 - Choosing a Pattern - lang_en_vs5.srt
deleted file mode 100644
index f273441..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/10 - Choosing a Pattern - lang_en_vs5.srt	
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-1
-00:00:00,150 --> 00:00:03,200
-But with so many patterns, how do we choose a pattern? So
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-2
-00:00:03,200 --> 00:00:05,970
-this is a possible approach that you can follow. First of all, you
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-3
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-want to make sure that you understand your design context. You understand
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-what you're designing and what are the issues involved with this design. What
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-are the problems that you need to solve. At this point, you
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-can examine the patterns catalog, or,if
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-you're already familiar with the catalog, just
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-8
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-think about the possible patterns that you could use. Once you identify
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-the patterns that you can use, you also want to study them and
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-study the related patterns. So normally if you look at any pattern catalog,
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-for each pattern there will also be a list of related patterns. So
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-you can also look at those to see whether maybe some of those
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-might be more applicable. And finally, once you identify the pattern that you
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-think is appropriate, you will apply that pattern. When you do that, just
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-be mindful that there are pitfalls in the use of patterns. One obvious
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-one is the fact that you might select the wrong pattern and make
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-your design worse instead of better. The second one is that if you
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-get too excited about patterns, then you
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-might be abusing patterns, so just using too
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-many patterns, and end up with a design
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-that is more complicated rather than less complicated.
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-So always be careful, spend the time to figure out which one is the right
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-pattern to apply, and make sure that you
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-don't use patterns that you don't actually need.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/11 - Choosing a Pattern Quiz - lang_en_vs4.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/11 - Choosing a Pattern Quiz - lang_en_vs4.srt
deleted file mode 100644
index 76a78e0..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/11 - Choosing a Pattern Quiz - lang_en_vs4.srt	
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@@ -1,31 +0,0 @@
-1
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-Now that we've discussed how to choose a pattern. Imagine that
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-you have to write a class that can have only one
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-instance. So to satisfy this requirement, I would like for you
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-to pick one of the design patterns that we discussed in
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-this lesson, and write the code here that satisfies that requirement.
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-And when you write the code, please make sure that your
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-class has only one method, without counting possible constructors, and that
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-the class is called Singleton. And write your class right here.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/12 - Choosing a Pattern Quiz Solution - lang_en_vs4.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/12 - Choosing a Pattern Quiz Solution - lang_en_vs4.srt
deleted file mode 100644
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--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/12 - Choosing a Pattern Quiz Solution - lang_en_vs4.srt	
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@@ -1,79 +0,0 @@
-1
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-As we discussed in the class the right thing to
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-do here was to use the factory pattern. So here is
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-a possible code to solve the problem. Of course that there
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-are different possible solutions. So what we did for this code
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-was to first create a private, static, Singleton object called
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-instance, which is the one that will keep track of the
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-only instance that can be created on the class. Then we
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-define the default constructor, the constructor that doesn't take any parameter
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-as private. In this way other classes cannot create instances
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-of Singleton without calling our factory method, and finally we
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-create the factory method. And the factory method is very
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-simple. The method will first check whether an instance of
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-the class was already created. If it was created, it
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-would just return that instance. Otherwise, it will create a
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-new instance and assign it to that instance member variable
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-and then return the newly created instance. So with this code
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-you're guaranteed that other classes cannot bypass the factory
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-method, because the default constructor is private. And the that
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-the factory method will create one and only one instance
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-of the class, which is exactly what our requirements were.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/13 - Negative Design Patterns - lang_en_vs4.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/13 - Negative Design Patterns - lang_en_vs4.srt
deleted file mode 100644
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--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/13 - Negative Design Patterns - lang_en_vs4.srt	
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@@ -1,51 +0,0 @@
-1
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-To conclude this lesson, I want to discuss the
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-concept of negative design patterns, that is, patterns that should
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-be avoided. Interestingly, negative patterns were also mentioned in
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-Christopher Alexander's book, so in the first formulation of patterns.
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-So negative design pattern are basically guidelines on how
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-not to do things. In consoles with patterns, the guidelines
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-on how to do things. So basically, what the negative
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-design patterns do is, they enable recurring design defects to
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-be avoided. And as we will see in this class extensively,
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-in mini-course four, negative patterns are
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-also called anti-patterns or bad smells,
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-or bad code smells. So in mini-course four we will see several
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-examples of bad smells and what we can do to eliminate them.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/2 - History of Design Patterns - lang_en_vs6.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/2 - History of Design Patterns - lang_en_vs6.srt
deleted file mode 100644
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--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/2 - History of Design Patterns - lang_en_vs6.srt	
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@@ -1,179 +0,0 @@
-1
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-Let's start our decision of design patterns by looking
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-at the history of patterns. As you know, I like
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-to give this sort of historical perspective on how and
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-when concepts were defined. In this case, we have to
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-go back to 1977, when Christopher Alexander, an American professor
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-of architecture at UC Berkeley, introduces the idea of patterns,
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-successful solutions to problems, in his book called a Pattern
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-Language. The book contains about 250 patterns. And the idea
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-is that occupants of a building should be able
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-to design it. And the patterns in the book provide
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-a way to do that. And this idea of design
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-patterns, so, a formal way of documenting successful solutions to
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-problems, inspired several other disciplines. In particular, in 1987,
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-Ward Cunningham and Kent Beck leveraged this idea of Alexander's
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-patterns in the context of an object oriented language.
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-And in this specific the language was Smalltalk.
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-Some of you might know the language. So what Cunningham
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-and Beck did, was to create a 5 pattern
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-language for guiding novice Smalltalk programmers. So they did
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-an experiment and had several developers using their patterns, and
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-the experiment was extremely successful. The users were able to
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-create elegant designs using the provided patterns. And in case
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-you are interested in reading about it, Cunningham and Beck
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-reported the results in the article, Using Pattern Languages for
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-Object Oriented Programs, which was published at the
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-International Conference on Object Oriented Programming, Systems, Languages, and
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-Applications, also called OOPSLA, in 1987. At the
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-same time, Eric Gamma was working on his dissertation,
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-whose topic was the importance of patterns and
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-how to capture them. Between 1987 and 1992, there
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-were several workshops related to design patterns. And
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-in 1992, Jim Coplien compiled a catalog of C++
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-items, which are some sort of patterns, and
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-he listed this catalog of patterns in his
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-book, which was titled Advanced C++ Programming Styles
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-and Idioms. Finally, in 1993 and 1994, there were
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-several additional workshops focused on patterns. And this
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-workshop brought together many patterns folks, including these
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-4 guys, Erich Gamma, Richard Helm, Ralph Johnson,
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-and John Vlissides. These guys are also known as
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-the gang of 4. And the result of this collaboration was the
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-famous book Design Patterns: Elements of
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-Reusable Object Oriented Software. So this
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-is basically The Book on design patterns. If you want to buy
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-a book on design pattern, this is the one you should get.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/3 - Patterns Catalogue - lang_en_vs4.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/3 - Patterns Catalogue - lang_en_vs4.srt
deleted file mode 100644
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--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/3 - Patterns Catalogue - lang_en_vs4.srt	
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-1
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-This book contains a patterns catalog which is
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-a number of design patterns classified by purpose. And
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-there are five main classes of patterns. There are
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-fundamental patterns which are the basic patterns. There are
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-creational patterns which are the patterns that support object
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-creation. Then there are structural patterns and these are
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-patterns that help compose objects, put objects together. The
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-next class of patterns are behavioral patterns and these
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-are patterns that are mostly focused on realizing interactions
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-among different objects. Finally, there are concurrency patterns and these
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-are patterns that support, as the name says, concurrency, so
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-they're more related to concurrency aspects. And for each of
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-these classes there are a number of specific patterns, and
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-here I'm just listing some of them. Clearly we cannot
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-cover in one lesson all of these patterns, but what
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-I want to do is to cover at least a few
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-of those to give an idea of what patterns are and
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-how they can be used. In particular, we will see in
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-detail the Factory Method Pattern and the Strategy Pattern. And we
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-will also discuss a few more patterns at a higher level.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/4 - Pattern Format - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/4 - Pattern Format - lang_en_vs5.srt
deleted file mode 100644
index 7df86c0..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/4 - Pattern Format - lang_en_vs5.srt	
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@@ -1,71 +0,0 @@
-1
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-So let's start by seeing how patterns are defined. So
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-what is the format of the pattern definitions. If we look
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-at the Gang of Four's book we can see that these
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-definitions contain a lot of information. In fact, what I'm listing
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-here is just a subset of this information. In this lesson,
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-what I want to do is to focus on four essential
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-elements of a design pattern. It's name, the intent which is
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-the goal of the pattern. The pattern's applicability which is the
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-list of situations or context in which the
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-pattern is applicable. I also want to cover the structure
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-and participants. Which is the static model that describes
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-the elements, so normally the classes or the object
-
-13
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-involved in the pattern. In addition to that
-
-14
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-the structure also describes
-
-15
-00:00:41,400 --> 00:00:44,420
-the relationships, responsibilities and collaborations
-
-16
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-among these classes or objects. Finally what I want
-
-17
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-to cover is sample code. So examples that illustrate
-
-18
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-the use of patterns.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/5 - Factory Method Pattern - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/5 - Factory Method Pattern - lang_en_vs5.srt
deleted file mode 100644
index c7ebddd..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/5 - Factory Method Pattern - lang_en_vs5.srt	
+++ /dev/null
@@ -1,179 +0,0 @@
-1
-00:00:00,012 --> 00:00:02,350
-Let's now look at the first design pattern that we
-
-2
-00:00:02,350 --> 00:00:05,700
-will discuss, the factory method pattern. And I'm going to start
-
-3
-00:00:05,700 --> 00:00:09,220
-by discussing the intent of the pattern and its applicability.
-
-4
-00:00:09,220 --> 00:00:12,210
-As far as the intent is concerned, the factory method pattern
-
-5
-00:00:12,210 --> 00:00:16,690
-allows for creating objects without specifying their class, by invoking
-
-6
-00:00:16,690 --> 00:00:19,370
-what we call a factory method. And what that is, is
-
-7
-00:00:19,370 --> 00:00:22,680
-a method whose main goal is to create class instances.
-
-8
-00:00:22,680 --> 00:00:25,510
-So when is this pattern useful? So when is it applicable?
-
-9
-00:00:25,510 --> 00:00:28,080
-For example, it is applicable in cases in which a class
-
-10
-00:00:28,080 --> 00:00:31,890
-cannot anticipate the type of object it must create. That is,
-
-11
-00:00:31,890 --> 00:00:34,800
-the type of an object is not known at compile time,
-
-12
-00:00:34,800 --> 00:00:37,800
-is not known until the code runs. A typical example of
-
-13
-00:00:37,800 --> 00:00:40,500
-this, are frameworks. So if you ever used a framework, you
-
-14
-00:00:40,500 --> 00:00:44,280
-will know that, normally, frameworks only know about interfaces and abstract
-
-15
-00:00:44,280 --> 00:00:47,450
-classes. So the exact type of the objects of these classes
-
-16
-00:00:47,450 --> 00:00:50,840
-is only known at runtime. The second case in which the factory
-
-17
-00:00:50,840 --> 00:00:53,835
-method pattern is applicable, is when a class wants its
-
-18
-00:00:53,835 --> 00:00:57,160
-subclasses to specify the type of objects it creates. And we'll
-
-19
-00:00:57,160 --> 00:00:59,920
-see an example of this in a minute. Finally, factory
-
-20
-00:00:59,920 --> 00:01:03,580
-method patterns are applicable when a class needs control over the
-
-21
-00:01:03,580 --> 00:01:06,760
-creation of its objects. And in this case, one possible
-
-22
-00:01:06,760 --> 00:01:09,380
-example is when there is a limit on the number of
-
-23
-00:01:09,380 --> 00:01:12,930
-objects that can be created. Special example, it's a singleton. If
-
-24
-00:01:12,930 --> 00:01:15,840
-you're familiar with a singleton, a singleton is a class for
-
-25
-00:01:15,840 --> 00:01:18,930
-which only one instance can be created. The factory method pattern
-
-26
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-is perfect in these cases, because it allows to control how many
-
-27
-00:01:21,760 --> 00:01:24,640
-objects get created. So in this case, it would allow the creation
-
-28
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-only of a single object. And from the second time that it
-
-29
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-is invoked, it will just return the object that was previously
-
-30
-00:01:30,040 --> 00:01:33,700
-created. Now let's go ahead and see how this pattern actually works,
-
-31
-00:01:33,700 --> 00:01:37,100
-and let's do that by discussing the structure and the participants for
-
-32
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-the pattern. The structure that is represented here, using the UML notation,
-
-33
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-includes three classes, the Creator, the ConcreteCreator,
-
-34
-00:01:45,530 --> 00:01:48,000
-and the Product. The Creator provides the
-
-35
-00:01:48,000 --> 00:01:50,710
-interface for the factory method. So this
-
-36
-00:01:50,710 --> 00:01:53,200
-here, is the interface for the factory method
-
-37
-00:01:53,200 --> 00:01:55,950
-that, when invoked, returns an object of
-
-38
-00:01:55,950 --> 00:01:59,440
-type Product. The ConcreteCreator provides the actual
-
-39
-00:01:59,440 --> 00:02:02,350
-method for creating the Product. So this
-
-40
-00:02:02,350 --> 00:02:06,170
-method is a concrete implementation of this interface.
-
-41
-00:02:06,170 --> 00:02:10,630
-Finally, the Product is the object created by the factory method. So
-
-42
-00:02:10,630 --> 00:02:12,350
-summarizing, we have the interface for
-
-43
-00:02:12,350 --> 00:02:14,300
-the factory method, the actual implementation of
-
-44
-00:02:14,300 --> 00:02:17,540
-the summary method, and the object that is created by the factory method,
-
-45
-00:02:17,540 --> 00:02:21,020
-when it is invoked. So let's look at an example of this pattern.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/6 - Factory Method Pattern Example - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/6 - Factory Method Pattern Example - lang_en_vs5.srt
deleted file mode 100644
index 2812c39..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/6 - Factory Method Pattern Example - lang_en_vs5.srt	
+++ /dev/null
@@ -1,127 +0,0 @@
-1
-00:00:00,220 --> 00:00:03,260
-The example I'm going to use consists of a class called
-
-2
-00:00:03,260 --> 00:00:07,380
-ImageReaderFactory which provides the factory method which is this one;
-
-3
-00:00:07,380 --> 00:00:10,250
-createImageReader. As you can see the method takes an InputStream
-
-4
-00:00:10,250 --> 00:00:13,570
-as input and returns an object of type ImageReader, and it's
-
-5
-00:00:13,570 --> 00:00:15,645
-static so that we can invoke it even if we
-
-6
-00:00:15,645 --> 00:00:18,390
-don't have an instance of the ImageReaderFactory. So what does the
-
-7
-00:00:18,390 --> 00:00:22,275
-method do? Well the method first invokes, getImageType, passing the
-
-8
-00:00:22,275 --> 00:00:25,780
-InputStream as a parameter and this method figures out the type
-
-9
-00:00:25,780 --> 00:00:28,820
-of the image that is stored in this Inputstream and it's
-
-10
-00:00:28,820 --> 00:00:32,740
-an integer. Then, based on the value of this integer, the
-
-11
-00:00:32,740 --> 00:00:35,352
-method does one of several things. If the image type is
-
-12
-00:00:35,352 --> 00:00:38,970
-a GIF, it will invoke the constructor for GifReader passing the
-
-13
-00:00:38,970 --> 00:00:41,610
-stream as a parameter. And what will happen is that the
-
-14
-00:00:41,610 --> 00:00:44,450
-GIF reader will read a GIF from the stream, create a
-
-15
-00:00:44,450 --> 00:00:47,887
-corresponding object and return it. So in this case, the ImageReader
-
-16
-00:00:47,887 --> 00:00:51,460
-object return will be the object representing a GIF as appropriate.
-
-17
-00:00:51,460 --> 00:00:54,610
-Similarly, if the image type is JPEG, then the method will
-
-18
-00:00:54,610 --> 00:00:58,579
-invoke the constructor for JPEG Reader and in this case, this constructor
-
-19
-00:00:58,579 --> 00:01:01,981
-will read from the stream a JPEG, create a corresponding object
-
-20
-00:01:01,981 --> 00:01:05,640
-and return it. And so on for different types of images. So
-
-21
-00:01:05,640 --> 00:01:07,880
-why is this a situation in which it is appropriate to
-
-22
-00:01:07,880 --> 00:01:11,100
-use the factory method pattern? One, because it corresponds exactly to the
-
-23
-00:01:11,100 --> 00:01:14,250
-cases that we saw before, of applicability. This is a case
-
-24
-00:01:14,250 --> 00:01:16,560
-in which we don't know the type of the object that we
-
-25
-00:01:16,560 --> 00:01:20,080
-need to create until we run the code, because it depends
-
-26
-00:01:20,080 --> 00:01:22,530
-on the value of the InputStream. It depends on the content
-
-27
-00:01:22,530 --> 00:01:25,590
-of the InputStream. So, until we read the InputStream, we cannot
-
-28
-00:01:25,590 --> 00:01:28,380
-figure out whether we need to create a GIF, a JPEG or
-
-29
-00:01:28,380 --> 00:01:30,780
-some other type of image. So in this case, we want to
-
-30
-00:01:30,780 --> 00:01:33,630
-do, we want to simply delegate to this classes the creation of
-
-31
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-the object, once we know what type of object needs to
-
-32
-00:01:35,610 --> 00:01:38,790
-be created. So perfect example of application of a factory method pattern.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/7 - Strategy Pattern - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/7 - Strategy Pattern - lang_en_vs5.srt
deleted file mode 100644
index 288b8d6..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/7 - Strategy Pattern - lang_en_vs5.srt	
+++ /dev/null
@@ -1,143 +0,0 @@
-1
-00:00:00,230 --> 00:00:02,110
-The second pattern I want to discuss is the
-
-2
-00:00:02,110 --> 00:00:05,050
-strategy pattern, which provides a way to configure a
-
-3
-00:00:05,050 --> 00:00:07,900
-class with one of many behaviors. What does that
-
-4
-00:00:07,900 --> 00:00:11,040
-mean? Well, more precisely, this pattern allows for defining
-
-5
-00:00:11,040 --> 00:00:15,330
-a family of algorithms, encapsulating them into separate classes,
-
-6
-00:00:15,330 --> 00:00:17,900
-so each algorithm in one class, and making these
-
-7
-00:00:17,900 --> 00:00:21,490
-classes interchangeable, but providing a common interface for all
-
-8
-00:00:21,490 --> 00:00:25,350
-the encapsulated algorithms. So in essence, the intent of
-
-9
-00:00:25,350 --> 00:00:29,250
-a strategy pattern is to allow for switching between
-
-10
-00:00:29,250 --> 00:00:33,490
-different algorithms for accomplishing a given task. For example, imagine
-
-11
-00:00:33,490 --> 00:00:36,610
-having different sorting algorithms with different space or time
-
-12
-00:00:36,610 --> 00:00:38,800
-tradeoffs. You might want to be able to have them
-
-13
-00:00:38,800 --> 00:00:42,670
-all available and use different ones in different situations.
-
-14
-00:00:42,670 --> 00:00:44,820
-And this pattern is applicable not only when we have
-
-15
-00:00:44,820 --> 00:00:47,260
-different variants of an algorithm, but also when we
-
-16
-00:00:47,260 --> 00:00:51,690
-have many related classes that differ only in their behavior.
-
-17
-00:00:51,690 --> 00:00:53,640
-So let's get more concrete and see how this is
-
-18
-00:00:53,640 --> 00:00:55,960
-done. And I'm going to do it as before, by
-
-19
-00:00:55,960 --> 00:00:59,700
-discussing the structure and the participants for this strategy pattern.
-
-20
-00:00:59,700 --> 00:01:02,540
-In this case, we have 3 types of participants for this
-
-21
-00:01:02,540 --> 00:01:07,210
-pattern, the context, the algorithm, and the concrete strategies. There
-
-22
-00:01:07,210 --> 00:01:09,580
-can be as many as the number of behaviors that
-
-23
-00:01:09,580 --> 00:01:12,300
-I need to implement. So, let's see what those are.
-
-24
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-The context is the interface to the outside world. It maintains
-
-25
-00:01:16,690 --> 00:01:19,180
-a reference to the current algorithm and allows for
-
-26
-00:01:19,180 --> 00:01:22,860
-updating this reference at run time. So, basically the outside
-
-27
-00:01:22,860 --> 00:01:26,370
-world will invoke the functionality provided by the different algorithms,
-
-28
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-by using this interface. And depending on which algorithm is
-
-29
-00:01:29,170 --> 00:01:31,640
-currently selected, that's the one that will be executed when
-
-30
-00:01:31,640 --> 00:01:35,920
-the functionality is involved. The algorithm, also called the strategy,
-
-31
-00:01:35,920 --> 00:01:37,970
-so that's where the pattern gets its name, Is the
-
-32
-00:01:37,970 --> 00:01:42,130
-common interface for the different algorithims. So all the algorithms
-
-33
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-implement this interface. Finally, the concrete strategies are the
-
-34
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-actual implementations of the algorithms. So if I have 10
-
-35
-00:01:49,920 --> 00:01:53,030
-different variants of my algorithm, I will implement 10 different
-
-36
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-concrete strategies. They will all be implementations of this interface.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/8 - Strategy Pattern Example & Demo - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/8 - Strategy Pattern Example & Demo - lang_en_vs5.srt
deleted file mode 100644
index 6d298d0..0000000
--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/8 - Strategy Pattern Example & Demo - lang_en_vs5.srt	
+++ /dev/null
@@ -1,511 +0,0 @@
-1
-00:00:00,130 --> 00:00:03,320
-Now let's see how this whole thing works in practice by
-
-2
-00:00:03,320 --> 00:00:06,800
-using an example. We're going to consider a program that takes as
-
-3
-00:00:06,800 --> 00:00:10,450
-input a text file and produce it as output, a filtered
-
-4
-00:00:10,450 --> 00:00:14,170
-file. So basically it outputs a subset of the content of
-
-5
-00:00:14,170 --> 00:00:16,928
-this text file based on some filter. And we're going to have
-
-6
-00:00:16,928 --> 00:00:19,440
-four different types of filters. So the first one is
-
-7
-00:00:19,440 --> 00:00:21,680
-not filtering which means that the whole content of the text
-
-8
-00:00:21,680 --> 00:00:25,320
-file will be produced on the output. The second filter will output
-
-9
-00:00:25,320 --> 00:00:27,990
-only words that starts with t. So you'll take the text file
-
-10
-00:00:27,990 --> 00:00:30,540
-and simply ignore all of the words that do not start with
-
-11
-00:00:30,540 --> 00:00:33,130
-t. So in the output we'll have only those words that starts
-
-12
-00:00:33,130 --> 00:00:36,030
-with letter t. The third filter will produce in the output only
-
-13
-00:00:36,030 --> 00:00:39,180
-words that are longer than five characters. So all the other words
-
-14
-00:00:39,180 --> 00:00:43,740
-will be simply disregarded. And finally, the four filter will produce as
-
-15
-00:00:43,740 --> 00:00:47,630
-output only words in the text file that are palindromes, and in
-
-16
-00:00:47,630 --> 00:00:50,590
-case you don't know what a palindrome is, a palindrome is a word
-
-17
-00:00:50,590 --> 00:00:52,700
-that is the same whether you read it from left
-
-18
-00:00:52,700 --> 00:00:55,800
-to right or from right to left. For example, the
-
-19
-00:00:55,800 --> 00:00:58,480
-word kayak, you can read it in this direction, or
-
-20
-00:00:58,480 --> 00:01:00,740
-in this direction, and it's exactly the same word. So
-
-21
-00:01:00,740 --> 00:01:03,560
-let's see how this program could be implemented using a
-
-22
-00:01:03,560 --> 00:01:05,980
-strategy pattern. And let's do it for real as a
-
-23
-00:01:05,980 --> 00:01:10,100
-demo. What we're looking at here is the editor page
-
-24
-00:01:10,100 --> 00:01:15,520
-for Eclipse, open with the strategy pattern implementation for our example.
-
-25
-00:01:15,520 --> 00:01:17,130
-So what I'm going to do is that, I'm going to look at a
-
-26
-00:01:17,130 --> 00:01:20,310
-different part of implementation. And you will see that, you know, despite
-
-27
-00:01:20,310 --> 00:01:23,420
-the fact that it's slightly longer, it's really fairly simple, it's kind
-
-28
-00:01:23,420 --> 00:01:26,230
-of a straightforward implementation of what we just saw. As I just
-
-29
-00:01:26,230 --> 00:01:29,820
-said, what we are doing is basically building the strategy patterns that
-
-30
-00:01:29,820 --> 00:01:34,330
-allows for changing the strategies with which we're filtering an input file.
-
-31
-00:01:34,330 --> 00:01:37,380
-And we have different strategies, we'll look at those in detail, and
-
-32
-00:01:37,380 --> 00:01:41,050
-we said that the three participants for this pattern are the context,
-
-33
-00:01:41,050 --> 00:01:43,650
-the algorithm, which is the general interface and then the concrete
-
-34
-00:01:43,650 --> 00:01:47,270
-strategies, which are the concrete implementations of this algorithm. So let's
-
-35
-00:01:47,270 --> 00:01:49,790
-start by looking at the context. Which is this class here.
-
-36
-00:01:49,790 --> 00:01:52,960
-And as you can see it contains a reference at the current
-
-37
-00:01:52,960 --> 00:01:56,240
-strategy. We call this the check strategy, which is basically our
-
-38
-00:01:56,240 --> 00:01:59,910
-filter, and when the context is created by default it sets a
-
-39
-00:01:59,910 --> 00:02:02,890
-strategy to the old strategy. The old strategy is the one
-
-40
-00:02:02,890 --> 00:02:06,380
-that accepts all the input, so basically it doesn't filter out anything.
-
-41
-00:02:06,380 --> 00:02:08,320
-And we said that the context is the interface to the
-
-42
-00:02:08,320 --> 00:02:10,889
-outside world, right? So it has to provide the outside world
-
-43
-00:02:10,889 --> 00:02:14,140
-with a way of selecting the strategy, the specific algorithm to
-
-44
-00:02:14,140 --> 00:02:16,850
-be used, and it does that in this case by providing
-
-45
-00:02:16,850 --> 00:02:21,360
-this change strategy method. This method takes a strategy as input,
-
-46
-00:02:21,360 --> 00:02:24,930
-and simply replaces the current strategy with the one specified as
-
-47
-00:02:24,930 --> 00:02:28,035
-a parameter. And at this point, the context also will perform
-
-48
-00:02:28,035 --> 00:02:31,830
-the filtering. The filtering is pretty straightforward, so what it does is
-
-49
-00:02:31,830 --> 00:02:34,620
-that it opens a file that is passed as a parameter
-
-50
-00:02:34,620 --> 00:02:37,450
-so that this the file, the input file to be filtered. And
-
-51
-00:02:37,450 --> 00:02:40,560
-then it reads the file line by line and then splits
-
-52
-00:02:40,560 --> 00:02:43,620
-the lines into its composing words and then for each word in
-
-53
-00:02:43,620 --> 00:02:46,480
-each line, what it will do, it will basically invoke the
-
-54
-00:02:46,480 --> 00:02:50,270
-check method in the current strategy, which is basically the filtering method
-
-55
-00:02:50,270 --> 00:02:53,580
-and if the check method returns true, which basically means that
-
-56
-00:02:53,580 --> 00:02:57,150
-the word should be printed, it prints the word. Otherwise, it'll just
-
-57
-00:02:57,150 --> 00:03:00,480
-skip it. So basically the filter will return false for all the
-
-58
-00:03:00,480 --> 00:03:03,470
-words that have to be filtered out. Okay? This is the basic
-
-59
-00:03:03,470 --> 00:03:06,770
-way in which context works. Let's see how this is used in
-
-60
-00:03:06,770 --> 00:03:10,660
-our main method. The main method simply creates the context, reads the input file
-
-61
-00:03:10,660 --> 00:03:12,910
-from the arguments, and then what he does is simply as a
-
-62
-00:03:12,910 --> 00:03:16,720
-demonstration, it will perform the filtering using all the different filters. So
-
-63
-00:03:16,720 --> 00:03:19,310
-starting from the default one, which is the one that basically doesn't
-
-64
-00:03:19,310 --> 00:03:22,150
-do any filtering that reports all words, then it will switch to the
-
-65
-00:03:22,150 --> 00:03:25,400
-algorithm, that only considers the words that start with t, and
-
-66
-00:03:25,400 --> 00:03:28,880
-it will do that by invoking a change strategy and passing this
-
-67
-00:03:28,880 --> 00:03:30,890
-strategy as the argument, and then
-
-68
-00:03:30,890 --> 00:03:32,760
-performing the actual filtering through context.
-
-69
-00:03:32,760 --> 00:03:35,040
-And it will do exactly the same for the strategy that only
-
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-prints words that are longer than five and the one that
-
-71
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-only prints words that are palindromes. So now let's look at the
-
-72
-00:03:40,460 --> 00:03:44,090
-actual algorithm. This is the interface, the algorithm interface. And you can
-
-73
-00:03:44,090 --> 00:03:47,080
-see that the only thing that the interface provides is this method,
-
-74
-00:03:47,080 --> 00:03:49,760
-which is the check method, that takes a string as input and will
-
-75
-00:03:49,760 --> 00:03:52,470
-return a boolean. So, basically, it's the boolean that we were seeing before.
-
-76
-00:03:52,470 --> 00:03:55,010
-The one that is true for the words that have to be printed
-
-77
-00:03:55,010 --> 00:03:57,490
-and false for the ones that have to be filtered out. Now, we have
-
-78
-00:03:57,490 --> 00:04:01,250
-all the different implementations of the algorithm, the simplest one is the all
-
-79
-00:04:01,250 --> 00:04:05,110
-algorithm, the simple return is always true, so all the words will be printed.
-
-80
-00:04:05,110 --> 00:04:08,740
-The second one starts with t, and again, without looking at the details
-
-81
-00:04:08,740 --> 00:04:10,660
-of implementations that don't really matter, what
-
-82
-00:04:10,660 --> 00:04:12,390
-it does is basically check that
-
-83
-00:04:12,390 --> 00:04:15,111
-the first character is t, and returns true in that case and
-
-84
-00:04:15,111 --> 00:04:17,720
-false otherwise. Similarly, for the LongerThan5
-
-85
-00:04:17,720 --> 00:04:19,380
-algorithm, also in this case, this
-
-86
-00:04:19,380 --> 00:04:23,000
-will implement the check strategy interface, and the check will be performed
-
-87
-00:04:23,000 --> 00:04:25,980
-by checking that the word is longer than five characters and returning
-
-88
-00:04:25,980 --> 00:04:29,440
-true in that case and false otherwise. And finally the Palindrome check
-
-89
-00:04:29,440 --> 00:04:32,240
-is a little more complicated, but basically it just checks whether the
-
-90
-00:04:32,240 --> 00:04:35,190
-word is a Palindrome and returns true in that case. Okay, so
-
-91
-00:04:35,190 --> 00:04:37,950
-as I said, it doesn't really matter too much what is the specific
-
-92
-00:04:37,950 --> 00:04:40,630
-implementations of these matters. What matters is that we have
-
-93
-00:04:40,630 --> 00:04:44,150
-a general interface for the algorithm and then any different concrete
-
-94
-00:04:44,150 --> 00:04:48,130
-implementations of the algorithm that implement different strategies. So again,
-
-95
-00:04:48,130 --> 00:04:50,730
-this allows you to change the behavior of your class without
-
-96
-00:04:50,730 --> 00:04:53,420
-changing class. So we have this context class that does
-
-97
-00:04:53,420 --> 00:04:57,015
-different things when the filter method in invoked, depending on what
-
-98
-00:04:57,015 --> 00:04:59,930
-is the current strategy. So the behavior of the class can
-
-99
-00:04:59,930 --> 00:05:03,310
-change dynamically, and it changes dynamically every time that we change
-
-100
-00:05:03,310 --> 00:05:06,300
-the strategy. At this point, the way this whole thing works should
-
-101
-00:05:06,300 --> 00:05:08,430
-be clear, so what we're going to do is that we're going to go to
-
-102
-00:05:08,430 --> 00:05:12,010
-our console, and we're actually going to run the strategy pattern and see
-
-103
-00:05:12,010 --> 00:05:15,710
-what happens. So here I have a file, it's called foo.txt. And if
-
-104
-00:05:15,710 --> 00:05:18,290
-we look at the content of foo, you can see that it
-
-105
-00:05:18,290 --> 00:05:21,190
-says that this is just a test to assess how well this program
-
-106
-00:05:21,190 --> 00:05:24,430
-performs when used on files of text. And since it checks for
-
-107
-00:05:24,430 --> 00:05:28,560
-palindromes, we will also insert one such word, level. Level is a palindrome,
-
-108
-00:05:28,560 --> 00:05:31,042
-because you can read it from both sides. Okay, so let's
-
-109
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-see what happens when we run our code. So we're going to
-
-110
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-run java pattern.strategy.StrategyPattern which is
-
-111
-00:05:36,900 --> 00:05:38,550
-our class, and we going to fetch
-
-112
-00:05:38,550 --> 00:05:41,460
-foo.txt as an input, and let's go back to the beginning
-
-113
-00:05:41,460 --> 00:05:43,980
-of the output to see what happened exactly. You can see
-
-114
-00:05:43,980 --> 00:05:48,040
-here that for the default strategy, which was the old strategy,
-
-115
-00:05:48,040 --> 00:05:50,810
-the whole file is printed, so every word is printed. This
-
-116
-00:05:50,810 --> 00:05:53,485
-is just a test to assess and so on and so forth,
-
-117
-00:05:53,485 --> 00:05:57,290
-as expected. For the filter that only prints words that
-
-118
-00:05:57,290 --> 00:06:00,230
-start with t, only words that start with t are printed,
-
-119
-00:06:00,230 --> 00:06:04,180
-again, as expected. Similarly, for the filter that only prints words
-
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-00:06:04,180 --> 00:06:06,970
-that are longer than 5, and finally for the one that prints
-
-121
-00:06:06,970 --> 00:06:09,540
-palindromes. And here you can see that we actually have two
-
-122
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-because the way in which this is implemented we'll also consider
-
-123
-00:06:12,410 --> 00:06:15,300
-single letter words as palindromes because you can read them from
-
-124
-00:06:15,300 --> 00:06:18,450
-both sides. But you definitely will also have level in the output.
-
-125
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-And in case you want to play with this code yourself, I
-
-126
-00:06:21,040 --> 00:06:24,600
-have made this code and also the implementation for examples of other
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-127
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-design partners available as a compressed archive. And the archive is accessible
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-through a URL that is provided in the notes for the cost.
diff --git a/usth/ICT2.7/P3L3 Design Patterns Subtitles/9 - Other Common Patterns - lang_en_vs5.srt b/usth/ICT2.7/P3L3 Design Patterns Subtitles/9 - Other Common Patterns - lang_en_vs5.srt
deleted file mode 100644
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--- a/usth/ICT2.7/P3L3 Design Patterns Subtitles/9 - Other Common Patterns - lang_en_vs5.srt	
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@@ -1,295 +0,0 @@
-1
-00:00:00,060 --> 00:00:03,460
-Before concluding this lesson, let's look at a few more patterns. And
-
-2
-00:00:03,460 --> 00:00:05,880
-although it will take too long to cover them in detail, I
-
-3
-00:00:05,880 --> 00:00:08,986
-would like to at least mention and quickly discuss a few more
-
-4
-00:00:08,986 --> 00:00:12,080
-of these more commonly-used patterns. In fact, some of the patterns that
-
-5
-00:00:12,080 --> 00:00:15,400
-I will discuss, you might have used yourself. Maybe without knowing their
-
-6
-00:00:15,400 --> 00:00:18,300
-name or the fact that they were design patterns. So let's start
-
-7
-00:00:18,300 --> 00:00:21,660
-with a Visitor pattern, which is a way of separating an algorithm
-
-8
-00:00:21,660 --> 00:00:25,150
-from an object structure on which it operates. And a practical result
-
-9
-00:00:25,150 --> 00:00:28,010
-of this separation is the ability to add the new operation
-
-10
-00:00:28,010 --> 00:00:31,680
-to exist in object structures, without modifying the structures. So, basically
-
-11
-00:00:31,680 --> 00:00:34,540
-what this pattern does, is to allow for defining and easily
-
-12
-00:00:34,540 --> 00:00:37,870
-modifying set of operations to perform on the objects of the collection.
-
-13
-00:00:37,870 --> 00:00:40,570
-And the typical usage of this is, for example, when you're
-
-14
-00:00:40,570 --> 00:00:43,140
-visiting a graph, or a set of objects, and you want
-
-15
-00:00:43,140 --> 00:00:46,090
-to perform some operations on these objects. By using a visitor
-
-16
-00:00:46,090 --> 00:00:48,410
-pattern, you can decouple the operation
-
-17
-00:00:48,410 --> 00:00:50,830
-from the objects. Although not straightforward,
-
-18
-00:00:50,830 --> 00:00:53,360
-this pattern is very, very useful. So, I really encourage you
-
-19
-00:00:53,360 --> 00:00:56,060
-to look at it in more detail and get familiar with it.
-
-20
-00:00:56,060 --> 00:00:59,040
-The second pattern I want to mention is the decorator pattern.
-
-21
-00:00:59,040 --> 00:01:02,820
-The decorator pattern is basically a wrapper that adds functionality to a
-
-22
-00:01:02,820 --> 00:01:05,030
-class. So the way in which it works, is that you
-
-23
-00:01:05,030 --> 00:01:08,230
-will take a class, you will build a class that basically wraps
-
-24
-00:01:08,230 --> 00:01:12,250
-this class. So it reproduces the functionality of the original class, but
-
-25
-00:01:12,250 --> 00:01:15,900
-it also adds some functionality. And for all the functionality that was
-
-26
-00:01:15,900 --> 00:01:18,750
-already in the original class, it will simply invoke this
-
-27
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-functionality and for the new one, you will implement it
-
-28
-00:01:21,080 --> 00:01:24,510
-using the services of the class. And a nice property
-
-29
-00:01:24,510 --> 00:01:26,760
-of the decorator pattern is that it's stackable. So you can
-
-30
-00:01:26,760 --> 00:01:30,210
-add decorators on decorators on decorators, and further increase the
-
-31
-00:01:30,210 --> 00:01:34,052
-functionality provided by your class. The iterator is another very
-
-32
-00:01:34,052 --> 00:01:37,810
-commonly-used pattern. And, you probably use this one yourself because,
-
-33
-00:01:37,810 --> 00:01:41,090
-it's also part of many standard libraries. What the iterator allows
-
-34
-00:01:41,090 --> 00:01:44,220
-you to do, is basically to access elements of a collection
-
-35
-00:01:44,220 --> 00:01:47,490
-without knowing the underlying representation. So the iterator will allow you
-
-36
-00:01:47,490 --> 00:01:50,630
-to just go through a set of objects without worrying about
-
-37
-00:01:50,630 --> 00:01:53,200
-how the objects are stored. So you basically just ask the
-
-38
-00:01:53,200 --> 00:01:55,810
-iterator to give you the first object, the next object and
-
-39
-00:01:55,810 --> 00:02:00,130
-so on. Another very commonly-used pattern is the observer pattern. And
-
-40
-00:02:00,130 --> 00:02:02,650
-this pattern is very useful when you have an object of
-
-41
-00:02:02,650 --> 00:02:06,190
-interest and a set of other objects that are interested in
-
-42
-00:02:06,190 --> 00:02:09,240
-the changes that might occur in this first object. So
-
-43
-00:02:09,240 --> 00:02:12,690
-what the observer pattern allows you to do is to register
-
-44
-00:02:12,690 --> 00:02:15,460
-these objects, so that they let the system know that
-
-45
-00:02:15,460 --> 00:02:18,690
-they're interested in changes in this first object. And then, every
-
-46
-00:02:18,690 --> 00:02:20,840
-time that there is a change, these other objects will
-
-47
-00:02:20,840 --> 00:02:23,030
-be automatically notified. So basically,
-
-48
-00:02:23,030 --> 00:02:25,290
-the observer pattern allows for notifying
-
-49
-00:02:25,290 --> 00:02:29,310
-dependents when an object of interest changes. If you want
-
-50
-00:02:29,310 --> 00:02:32,020
-an example of this, just think about the file system and
-
-51
-00:02:32,020 --> 00:02:35,870
-imagine having a folder. All the views of this folder will
-
-52
-00:02:35,870 --> 00:02:37,970
-want to be notified every time that there's a change in
-
-53
-00:02:37,970 --> 00:02:40,720
-the folder because they need to refresh. So instead of continuously
-
-54
-00:02:40,720 --> 00:02:44,390
-checking the state of the folder, they will just register and basically
-
-55
-00:02:44,390 --> 00:02:47,430
-say, hey, we're interested in knowing when something changes in this
-
-56
-00:02:47,430 --> 00:02:50,320
-folder. And when something changes in the folder, they will be automatically
-
-57
-00:02:50,320 --> 00:02:53,300
-notified. So it will be some sort of a push notification
-
-58
-00:02:53,300 --> 00:02:56,590
-instead of a pull notification, if you are familiar with that terminology.
-
-59
-00:02:56,590 --> 00:03:00,020
-Finally the proxy pattern is a pattern in which a surrogate
-
-60
-00:03:00,020 --> 00:03:04,370
-controls access to an object. In other words, we have our object,
-
-61
-00:03:04,370 --> 00:03:07,220
-and we have our proxy here. So all the requests to the
-
-62
-00:03:07,220 --> 00:03:09,950
-object will go through the proxy that will then forward them. And
-
-63
-00:03:09,950 --> 00:03:12,020
-all the responses from the object will also go through the
-
-64
-00:03:12,020 --> 00:03:15,580
-proxy. They will then forward them to the original requester. So what
-
-65
-00:03:15,580 --> 00:03:18,710
-the proxy allows you to do is to control how this object,
-
-66
-00:03:18,710 --> 00:03:22,180
-that is behind the proxy, is actually accessed, for example, by filtering
-
-67
-00:03:22,180 --> 00:03:24,500
-some calls. So in a sense, the proxy allows use
-
-68
-00:03:24,500 --> 00:03:27,470
-for masking some of the functionality of the object that
-
-69
-00:03:27,470 --> 00:03:31,070
-is behind the proxy. And there's many, many, many more
-
-70
-00:03:31,070 --> 00:03:34,424
-useful patterns. That can help you when designing and implementing
-
-71
-00:03:34,424 --> 00:03:37,220
-the system. So once more, I really encourage you to
-
-72
-00:03:37,220 --> 00:03:38,740
-have a look at the book, to look at the
-
-73
-00:03:38,740 --> 00:03:41,570
-resources online, and to really get more familiar with these
-
-74
-00:03:41,570 --> 00:03:43,890
-patterns, and to try to use them in your everyday work.
-- 
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