Re: [Chicken-users] do I use define-foreign-variable correctly ?

[Kon Lovett]

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On Feb 7, 2007, at 6:41 AM, minh thu wrote:

> #>!
> #include <X.h>
> #include <keysym.h>
> <#
>
> (define-foreign-variable c-escape-key int "XK_Escape")
> (define escape-key c-escape-key)
>
> Do I need to have those two lines too be able to use escape-key as a
> Scheme symbol for the C #defined XK_Escape value ?

Umm, depends. Do you want it visible outside of the compilation unit  
(i.e. exportable)? then '(define escape-key (foreign-value  
"XK_Escape" int))' is enough. (I might make the symbol uppercase just  
to emphasize it is a constant.) Also 'define-foreign-variable' has  
overhead that you don't want for a constant, it isn't mutable so  
conversion should only be done once. ('foreign-value' is a wrapper  
around 'define-foreign-variable' that creates the variable, gets its'  
value, & throws away the variable, returning only the value.)

> Thanks,
> thu
>
>
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> Chicken-users mailing list
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