Andreas: Thanks for the replies. I did all of what you told me but I got this error when trying to call the api:<br><br>'External library is invalid'<br><br>I even try to execute: ExternalLibrary initialize.<br><br>
However, I am not convinced why this way is better than having module: aString.<br><br>Disadvantages of this new way:<br><br>- I am "coupling" or "hardcoding" not only the library name but also the location in the file system. Perhaps I rather this be automatically done by FFI. <br>
<br>Advantages of this new way:<br>
<br>
- I can add as many names or paths as I want to my library. <br>
<br>what do you think? can you help me with the advantages and disadvantages from both alternatives?<br><br>
Thanks!<br><br>Mariano<br><br><br><br><div class="gmail_quote">On Fri, May 1, 2009 at 5:44 PM, Bert Freudenberg <span dir="ltr"><<a href="mailto:bert@freudenbergs.de" target="_blank">bert@freudenbergs.de</a>></span> wrote:<br>
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On 01.05.2009, at 17:48, Andreas Raab wrote:<br>
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Bert Freudenberg wrote:<br>
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On 30.04.2009, at 23:55, Andreas Raab wrote:<br>
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Bert Freudenberg wrote:<br>
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On 30.04.2009, at 23:22, Mariano Martinez Peck wrote:<br>
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However, you can of course manually do the "linking" step - in the<br>
ffi function declarations, use "libopendbx.so.1" as module instead<br>
of just "opendbx". This will then only work on Linux of course,<br>
since other Unix platforms use different schemes of versioning<br>
libraries.<br>
<br>
<br>
Indeed. That's why I don't want to change the module name.<br>
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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 ...<br>
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<br>
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:<br>
<br>
MyLibrary class>>moduleName<br>
"Answer the module name to use for this library"<br>
Smalltalk platformName = 'Win32' ifTrue:[^'MyLibrary32.dll'].<br>
Smalltalk platformName = 'unix' ifTrue:[<br>
"check various locations and versions"<br>
#('/usr/lib/libMyLibrary.so'<br>
'/usr/lib/libMyLibrary.so.1'<br>
'/usr/lib/libMyLibrary.so.2'<br>
'/usr/share/libMyLibrary.so.1'<br>
'/usr/share/libMyLibrary.so.2') do:[:location|<br>
(FileDirectory fileExists: location) ifTrue:[^location].<br>
].<br>
^self error:'MyLibrary is not installed'<br>
].<br>
<br>
etc.<br>
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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?<br>
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<br>
Define it in a subclass of ExternalLibrary. Functions defined in a subclass of ExternalLibrary without a module: string use the moduleName from the time the library is instantiated. The module: string was really only intended for convenience such that one could declare FFI functions where it is most convenient instead of having to use ExternalLibrary subclasses.<br>
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That's a useful trick, thanks. Have not ever seen it before.<br><font color="#888888">
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<br>
- Bert -<br>
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