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Added clarifying notes emphasizing that dynamic-require is a procedure so

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giving plain s-exps like you would for `require` is unlikely to work as expected.
Need use something that evaluates to the appropriate s-exp you want.

Added more examples of different `dynamic-require` uses.
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Alexander McLin 2018-05-25 14:00:05 -04:00 committed by Ben Greenman
parent 4e10ed0518
commit 5d1371cb73
1 changed files with 35 additions and 0 deletions
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35
pkgs/racket-doc/scribblings/reference/module-reflect.scrbl
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@ -476,6 +476,11 @@ Return @racket[#t] if @racket[compiled-module-code] represents a
[fail-thunk (-> any) (lambda () ....)])
(or/c void? any/c)]{
@margin-note{Because @racket[dynamic-require] is a procedure, giving a plain S-expression for
@racket[mod] the same way as you would for a @racket[require] expression likely won't give you
expected results. What you need instead is something that evaluates to an S-expression; using
@racket[quote] is one way to do it.}
Dynamically @tech{instantiates} the module specified by @racket[mod]
in the current namespace's registry at the namespace's @tech{base
phase}, if it is not yet @tech{instantiate}d. The current @tech{module
@ -494,6 +499,11 @@ above the @tech{base phase}.
(dynamic-require ''a #f)
]
@margin-note{The double quoted @racket[''a] evaluates to the @racket[root-module-path] @racket['a]
(see the grammar for @racket[require]). Using @racket['a] or @racket[a] for @racket[mod] won't work
because the former evaluates to @racket[root-module-path] @racket[a] which fails since the example is
not a module installed in a collection, the latter is an undefined variable.}
When @racket[provided] is a symbol, the value of the module's export
with the given name is returned, and still the module is not
@tech{visit}ed or made @tech{available} in higher phases.
@ -535,6 +545,31 @@ If @racket[provided] is @|void-const|, then the module is
@tech{visit}ed but not @tech{instantiate}d (see @secref["mod-parse"]),
and the result is @|void-const|.}
More examples using different @racket[module-path] grammar expressions are given below:
@examples[#:eval mod-eval
(dynamic-require 'racket/base #f)
]
@examples[#:eval mod-eval
(dynamic-require (list 'lib "racket/base") #f)
]
@examples[#:eval mod-eval
(module a racket/base
(module b racket/base
(provide inner-dessert)
(define inner-dessert "tiramisu")))
(dynamic-require '(submod 'a b) 'inner-dessert)
]
The last line in the above example could instead have been written as
@examples[#:eval mod-eval
(dynamic-require ((lambda () (list 'submod ''a 'b))) 'inner-dessert)
]
which is equivalent.
@defproc[(dynamic-require-for-syntax [mod module-path?]
[provided (or/c symbol? #f)]