11 Dynamic Loading

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11Dynamic Loading🔗 i

(require racket/gui/dynamic ) package: base

The racket/gui/dynamic library provides functions for dynamically accessing the racket/gui/base library, instead of directly requiring racket/gui or racket/gui/base.

procedure
( gui-available? )→boolean?

Returns #t if dynamic access to the GUI bindings is available. The bindings are available if racket/gui/base has been loaded, instantiated, and attached to the namespace in which racket/gui/dynamic was instantiated.

procedure
( gui-dynamic-require sym)→any
sym:symbol?

Like dynamic-require , but specifically to access exports of racket/gui/base, and only when (gui-available? ) returns true.

The gui-dynamic-require function is intended primarily for use under a (gui-available? ) conditional. It can also be used as a shorthand for dynamic-require with 'racket/gui/base, but only after ensuring that the bindings are available. One way to make racket/gui/base bindings available, so that (gui-available? ) returns true, is through dynamic-require :

(dynamic-require 'racket/gui/base#f)

Unlike require , using dynamic-require delays the instantiation of racket/gui/base until the run-time call of dynamic-require . With racket/gui/base so declared, gui-dynamic-require can be used to access bindings:

(define window(new (gui-dynamic-require 'frame%)
[label"Frame"]))
(send windowshow#t)

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