[squeak-dev] Re: FFI question [WAS] squeakopendbx, which VM?
Bert Freudenberg
bert at freudenbergs.de
Fri May 1 09:22:13 UTC 2009
On 30.04.2009, at 23:55, Andreas Raab wrote:
> Bert Freudenberg wrote:
>> On 30.04.2009, at 23:22, Mariano Martinez Peck wrote:
>>> However, you can of course manually do the "linking" step - in
>>> the
>>> ffi function declarations, use "libopendbx.so.1" as module
>>> instead
>>> of just "opendbx". This will then only work on Linux of course,
>>> since other Unix platforms use different schemes of versioning
>>> libraries.
>>>
>>>
>>> Indeed. That's why I don't want to change the module name.
>> Well, you can also automate this "pseudo-linking". When starting
>> up, just patch the right module name for the current platform into
>> all the FFI declarations. That's how the OpenGL FFI bindings in
>> Croquet work ...
>
> The way this is done is purely for historical reasons (and an
> *extremely* bad example that should not be taught to anyone). The
> Right Way to do this is to have a subclass of ExternalLibrary and
> implement the class-side method #moduleName along the lines of:
>
> MyLibrary class>>moduleName
> "Answer the module name to use for this library"
> Smalltalk platformName = 'Win32' ifTrue:[^'MyLibrary32.dll'].
> Smalltalk platformName = 'unix' ifTrue:[
> "check various locations and versions"
> #('/usr/lib/libMyLibrary.so'
> '/usr/lib/libMyLibrary.so.1'
> '/usr/lib/libMyLibrary.so.2'
> '/usr/share/libMyLibrary.so.1'
> '/usr/share/libMyLibrary.so.2') do:[:location|
> (FileDirectory fileExists: location) ifTrue:[^location].
> ].
> ^self error:'MyLibrary is not installed'
> ].
>
> etc.
Interesting. I thought the module in an FFI function declaration
needed to be a literal string. How would you declare it to use
MyLibrary instead?
- Bert -
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