11 Dynamic Loading
| (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
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 window show #t)