From efe7d19a9edafb793dca21dcefce89ead3465030 Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Sat, 15 Apr 2017 22:12:37 +0200 Subject: services: 'service-parameters' becomes 'service-value'. * gnu/services.scm ()[parameters]: Rename to... [value]: ... this. Change calls to 'service-parameters' to 'service-value'. * gnu/system.scm, gnu/tests/base.scm, guix/scripts/system.scm, tests/services.scm: Likewise. * doc/guix.texi (Service Reference): Adjust accordingly. --- gnu/services.scm | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) (limited to 'gnu/services.scm') diff --git a/gnu/services.scm b/gnu/services.scm index 9f6e323e18..af4cffe819 100644 --- a/gnu/services.scm +++ b/gnu/services.scm @@ -51,7 +51,8 @@ service service? service-kind - service-parameters + service-value + service-parameters ;deprecated simple-service modify-services @@ -142,10 +143,14 @@ ;; Services of a given type. (define-record-type - (service type parameters) + (service type value) service? (type service-kind) - (parameters service-parameters)) + (value service-value)) + +(define service-parameters + ;; Deprecated alias. + service-value) (define (simple-service name target value) "Return a service that extends TARGET with VALUE. This works by creating a @@ -161,7 +166,7 @@ singleton service type NAME, of which the returned service is an instance." service) ((_ svc (kind param => exp ...) clauses ...) (if (eq? (service-kind svc) kind) - (let ((param (service-parameters svc))) + (let ((param (service-value svc))) (service (service-kind svc) (begin exp ...))) (%modify-service svc clauses ...))))) @@ -321,7 +326,7 @@ file." (define* (activation-service->script service) "Return as a monadic value the activation script for SERVICE, a service of ACTIVATION-SCRIPT-TYPE." - (activation-script (service-parameters service))) + (activation-script (service-value service))) (define (activation-script gexps) "Return the system's activation script, which evaluates GEXPS." @@ -432,7 +437,7 @@ and FILE could be \"/usr/bin/env\"." (define (etc-directory service) "Return the directory for SERVICE, a service of type ETC-SERVICE-TYPE." - (files->etc-directory (service-parameters service))) + (files->etc-directory (service-value service))) (define (files->etc-directory files) (file-union "etc" files)) @@ -605,7 +610,7 @@ TARGET-TYPE; return the root service adjusted accordingly." (match (find (matching-extension target) (service-type-extensions (service-kind service))) (($ _ compute) - (compute (service-parameters service)))))) + (compute (service-value service)))))) (match (filter (lambda (service) (eq? (service-kind service) target-type)) @@ -616,7 +621,7 @@ TARGET-TYPE; return the root service adjusted accordingly." (extensions (map (apply-extension sink) dependents)) (extend (service-type-extend (service-kind sink))) (compose (service-type-compose (service-kind sink))) - (params (service-parameters sink))) + (params (service-value sink))) ;; We distinguish COMPOSE and EXTEND because PARAMS typically has a ;; different type than the elements of EXTENSIONS. (if extend -- cgit 1.4.1 From 1bb895eabf74a1e571887eb1521915e668a5c28d Mon Sep 17 00:00:00 2001 From: Ludovic Courtès Date: Sat, 15 Apr 2017 23:53:23 +0200 Subject: services: Service types can now specify a default value for instances. * gnu/services.scm (&no-default-value): New variable. ()[default-value]: New field. (): Rename constructor from 'service' to 'make-service'. (service): New macro. (%service-with-default-value): New procedure. (&missing-value-service-error): New error condition. * tests/services.scm ("services, default value"): New test. * doc/guix.texi (Service Types and Services): Document 'default-value'. (Service Reference): Explain default values. --- doc/guix.texi | 39 ++++++++++++++++++++++++++++++---- gnu/services.scm | 62 +++++++++++++++++++++++++++++++++++++++++++++++++----- tests/services.scm | 11 ++++++++++ 3 files changed, 103 insertions(+), 9 deletions(-) (limited to 'gnu/services.scm') diff --git a/doc/guix.texi b/doc/guix.texi index bf46f89bf2..fdd71141f0 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -15555,11 +15555,12 @@ with a simple example, the service type for the Guix build daemon (extensions (list (service-extension shepherd-root-service-type guix-shepherd-service) (service-extension account-service-type guix-accounts) - (service-extension activation-service-type guix-activation))))) + (service-extension activation-service-type guix-activation))) + (default-value (guix-configuration)))) @end example @noindent -It defines two things: +It defines three things: @enumerate @item @@ -15572,6 +15573,9 @@ service, returns a list of objects to extend the service of that type. Every service type has at least one service extension. The only exception is the @dfn{boot service type}, which is the ultimate service. + +@item +Optionally, a default value for instances of this type. @end enumerate In this example, @var{guix-service-type} extends three services: @@ -15607,7 +15611,13 @@ A service of this type is instantiated like this: The second argument to the @code{service} form is a value representing the parameters of this specific service instance. @xref{guix-configuration-type, @code{guix-configuration}}, for -information about the @code{guix-configuration} data type. +information about the @code{guix-configuration} data type. When the +value is omitted, the default value specified by +@code{guix-service-type} is used: + +@example +(service guix-service-type) +@end example @var{guix-service-type} is quite simple because it extends other services but is not extensible itself. @@ -15670,10 +15680,31 @@ Services}). This section provides a reference on how to manipulate services and service types. This interface is provided by the @code{(gnu services)} module. -@deffn {Scheme Procedure} service @var{type} @var{value} +@deffn {Scheme Procedure} service @var{type} [@var{value}] Return a new service of @var{type}, a @code{} object (see below.) @var{value} can be any object; it represents the parameters of this particular service instance. + +When @var{value} is omitted, the default value specified by @var{type} +is used; if @var{type} does not specify a default value, an error is +raised. + +For instance, this: + +@example +(service openssh-service-type) +@end example + +@noindent +is equivalent to this: + +@example +(service openssh-service-type + (openssh-configuration)) +@end example + +In both cases the result is an instance of @code{openssh-service-type} +with the default configuration. @end deffn @deffn {Scheme Procedure} service? @var{obj} diff --git a/gnu/services.scm b/gnu/services.scm index af4cffe819..b1b53fd18b 100644 --- a/gnu/services.scm +++ b/gnu/services.scm @@ -25,6 +25,7 @@ #:use-module (guix profiles) #:use-module (guix sets) #:use-module (guix ui) + #:use-module ((guix utils) #:select (source-properties->location)) #:use-module (guix modules) #:use-module (gnu packages base) #:use-module (gnu packages bash) @@ -47,6 +48,7 @@ service-type-extensions service-type-compose service-type-extend + service-type-default-value service service? @@ -60,6 +62,9 @@ fold-services service-error? + missing-value-service-error? + missing-value-service-error-type + missing-value-service-error-location missing-target-service-error? missing-target-service-error-service missing-target-service-error-target-type @@ -119,6 +124,10 @@ (target service-extension-target) ; (compute service-extension-compute)) ;params -> params +(define &no-default-value + ;; Value used to denote service types that have no associated default value. + '(no default value)) + (define-record-type* service-type make-service-type service-type? (name service-type-name) ;symbol (for debugging) @@ -132,7 +141,11 @@ ;; Extend the services' own parameters with the extension composition. (extend service-type-extend ;list of Any -> parameters - (default #f))) + (default #f)) + + ;; Optional default value for instances of this type. + (default-value service-type-default-value ;Any + (default &no-default-value))) (define (write-service-type type port) (format port "#" @@ -143,11 +156,53 @@ ;; Services of a given type. (define-record-type - (service type value) + (make-service type value) service? (type service-kind) (value service-value)) +(define-syntax service + (syntax-rules () + "Return a service instance of TYPE. The service value is VALUE or, if +omitted, TYPE's default value." + ((_ type value) + (make-service type value)) + ((_ type) + (%service-with-default-value (current-source-location) + type)))) + +(define (%service-with-default-value location type) + "Return a instance of service type TYPE with its default value, if any. If +TYPE does not have a default value, an error is raised." + ;; TODO: Currently this is a run-time error but with a little bit macrology + ;; we could turn it into an expansion-time error. + (let ((default (service-type-default-value type))) + (if (eq? default &no-default-value) + (let ((location (source-properties->location location))) + (raise + (condition + (&missing-value-service-error (type type) (location location)) + (&message + (message (format #f (_ "~a: no value specified \ +for service of type '~a'") + (location->string location) + (service-type-name type))))))) + (service type default)))) + +(define-condition-type &service-error &error + service-error?) + +(define-condition-type &missing-value-service-error &service-error + missing-value-service-error? + (type missing-value-service-error-type) + (location missing-value-service-error-location)) + + + +;;; +;;; Helpers. +;;; + (define service-parameters ;; Deprecated alias. service-value) @@ -541,9 +596,6 @@ kernel." ;;; Service folding. ;;; -(define-condition-type &service-error &error - service-error?) - (define-condition-type &missing-target-service-error &service-error missing-target-service-error? (service missing-target-service-error-service) diff --git a/tests/services.scm b/tests/services.scm index 7983427a7d..8484ee982a 100644 --- a/tests/services.scm +++ b/tests/services.scm @@ -31,6 +31,17 @@ (test-begin "services") +(test-equal "services, default value" + '(42 123 234 error) + (let* ((t1 (service-type (name 't1) (extensions '()))) + (t2 (service-type (name 't2) (extensions '()) + (default-value 42)))) + (list (service-value (service t2)) + (service-value (service t2 123)) + (service-value (service t1 234)) + (guard (c ((missing-value-service-error? c) 'error)) + (service t1))))) + (test-assert "service-back-edges" (let* ((t1 (service-type (name 't1) (extensions '()) (compose +) (extend *))) -- cgit 1.4.1