使用 ASDF 加载可选组件

Question

如何告诉 ASDF 仅在组件文件存在时才对其进行处理（因此如果组件文件尚不存在则不会生成错误）。

(asdf:defsystem "my-system"
  :components ((:file "utilities")
               (:file "temp-file" :depends-on ("utilities"))))

我的解决方法是使用 reader 宏#。在 (probe-file "temp-file") 上，但无法正常工作。

Answer 1

我认为您真正想要做的是让 ASDF 只是警告您，而不是在编译错误期间启动调试器。更改*compile-file-warnings-behaviour*和*compile-file-failure-behaviour*，并阅读手册中的the section on error handling。

这个答案的其余部分是如何检查整个系统。您可以将 maybe-to-load 文件打包到他们自己的系统中，然后按照下面的方式进行。

来自ASDF Manual section 6.3.8.

6.3.8 Weakly depends on

We do NOT recommend you use this feature.

所以你无论如何都可以使用它。像这样：

(defpackage :foo-system
  (:use :cl :asdf))
(in-package :foo-system)
(defsystem foo
  :description "The main package that maybe loads bar if it exists."
  :weakly-depends-on (:bar)
  :components ((:file "foo")))

简单吧？

这是他们的推荐：

If you are tempted to write a system foo that weakly-depends-on a system bar, we recommend that you should instead write system foo in a parametric way, and offer some special variable and/or some hook to specialize its behaviour; then you should write a system foo+bar that does the hooking of things together.

我从来没有在野外见过其中一个，可能是因为那样做会让人感到非常混乱。

(defpackage :bar-system
  (:use :cl :asdf))
(in-package :bar-system)
(defsystem bar
  :description "The package that maybe exists and is needed by foo."
  :components ((:file "bar")))

(defpackage :foo+bar-system
  (:use :cl :asdf))
(in-package :foo+bar-system)
(defsystem foo+bar
  :version      "0.1.0"
  :description  "Hook together foo and bar."
  :author       "Spenser Truex <web@spensertruex.com>"
  :serial       t
  :components ((:file "foo+bar")))

(defpackage :foo-system
  (:use :cl :asdf))
(in-package :foo-system)
(defsystem foo
  :description "The main package that maybe loads bar if it exists."
  :depends-on (:foo+bar)
  :components ((:file "foo")))

使用 ASDF 加载可选组件

Loading an Optional Component with ASDF

common-lisp

asdf