From: Eric Hodel <drbrain@...7.net>
Date: 2005-03-24T06:10:07+09:00
Subject: Re: Stack, Struct and DL

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On 23 Mar 2005, at 12:59, Luc Heinrich wrote:

> Luc Heinrich <lucsky@mac.com> wrote:
>
>> /usr/local/lib/ruby/1.8/dl/import.rb:125:in `symbol': can't find the
>> symbol `make_a_foo' (RuntimeError)
>
> And to make sure we're on the same page, here's exactly what I do 
> (this,
> of course, is just a test case to reproduce a problem that I have in a
> bigger project ;) ):

You'll have to teach DL what type FOO is.  Unfortunately, DL doesn't 
barf on you in a friendly way when it can't recognize a type.

> [ ------ foo.rb ------ ]
>
> require 'dl/import'
> require 'dl/struct'
>
> module Foo
>     extend DL::Importable
>     dlload 'foo.dylib'

     typealias "FOO", "void *"

Something like this should do it.  (Yeah, void * is probably the wrong 
type, see dl/types for what types dl knows about.)

>     FOO = struct [ "int bar", "int baz" ]
>     extern 'FOO make_a_foo(void)'  # this fails
>     extern 'FOO make_a_foo()'      # this fails too
>
>     def my_make_a_foo
>         return FOO.new( make_a_foo )
>     end
>
> end
>
> [ -------------------- ]
>
> The library is compiled as a dylib (I'm on OSX) using:
> $ cc -c foo.c
> $ libtool -dynamic -o foo.dylib foo.o
>
> If I then do:
> $ ruby foo.rb
>
> I get:
>
> /usr/local/lib/ruby/1.8/dl/import.rb:125:in `symbol': can't find the
> symbol `make_a_foo' (RuntimeError)
>         from /usr/local/lib/ruby/1.8/dl/import.rb:144:in `import'
>         from /usr/local/lib/ruby/1.8/dl/import.rb:61:in `extern'
>         from foo.rb:9
>
> -- 
> Luc Heinrich - lucsky@mac.com
>

-- 
Eric Hodel - drbrain@segment7.net - http://segment7.net
FEC2 57F1 D465 EB15 5D6E  7C11 332A 551C 796C 9F04

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