Re: [Fwd: guile-1.7.x and load-extension]

Re: [Fwd: guile-1.7.x and load-extension]

[Rob Browning]

David Pirotte <david@altosw.be> writes:

>> since I use guile, notably guile-1.5.4 and more recently cvs
>> versions of guile-1.7, up to 5th dec 01 (or a very close day around
>> the 5th, can't remember exactly), it accepted to load the '.so'
>> libraries.
>> 
>> now it seems to only look for '.la' libraries, see the strace
>> output below. the '.so' libraries are present:

Did you ever get this resolved?

If not, a few things to watch:

  * In newer guiles, load-extension is deprecated and should be
    replaced with something like

      (define-module (my module))
      (dynamic-call "init_my_lib" (dynamic-link "libmylib"))
      (export bar)
      (export baz)

  * Newer versions of libtool really don't seem to like you adding
    extensions to the library name.  So say (dynamic-link "libfoo")
    rather than (dynamic-link "libfoo.so").

  * I believe your shared libs must be fully linked against everything
    they depend on, but there won't necessarily be warnings at compile
    time if you forget something, you'll just get a relocation or
    segfault error at runtime when you try to dynamic-link.  In guile
    1.4 and eariler, the error message was somewhat cryptic, but newer
    guile's will actually tell you what guile was trying to link (at
    least the top-level lib) when the load failed.  We can't have more
    detailed info until/unless libtool (or ldl?) is enhanced to return
    more than just static error strings.

  * Make sure your LD_LIBRARY_PATH and LTDL_LIBRARY_PATH (if you have
    it set) are reasonable.

  * if you have a version of guile installed in /usr/ (along with it's
    development .so libs), but are trying to compile an app or lib
    against another version of guile installed elsewhere, make sure
    you don't build let a linker flag of -L/usr/lib sneak in before
    -lguile, -lqthreads, etc. on the gcc command line.  If you do,
    your app/lib may get linked against the wrong version of the guile
    libs., or even linked against more than one version.  Note that
    you have to be particularly watchful when your build flags are
    being generated by foo-config style scripts.

Hope this helps.

-- 
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
GPG=1C58 8B2C FB5E 3F64 EA5C  64AE 78FE E5FE F0CB A0AD

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Re: [Fwd: guile-1.7.x and load-extension]

[Marius Vollmer]

Rob Browning <rlb@defaultvalue.org> writes:

> David Pirotte <david@altosw.be> writes:
> 
> >> since I use guile, notably guile-1.5.4 and more recently cvs
> >> versions of guile-1.7, up to 5th dec 01 (or a very close day around
> >> the 5th, can't remember exactly), it accepted to load the '.so'
> >> libraries.
> >> 
> >> now it seems to only look for '.la' libraries, see the strace
> >> output below. the '.so' libraries are present:
> 
> Did you ever get this resolved?
> 
> If not, a few things to watch:
> 
>   * In newer guiles, load-extension is deprecated and should be
>     replaced with something like

Nooo!  It's the other way around: load-extension is the new thing, and
you should use it in preference to a dynamic-link/dynamic-call combo.
However, dynamic-link and dynamic-call are not deprecated since they
are useful on its own.

Apparently some docs about this are confusing.  Can you say where you
learned that load-extension is deprecated?

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Re: [Fwd: guile-1.7.x and load-extension]

[Rob Browning]

Marius Vollmer <mvo@zagadka.ping.de> writes:

> Nooo!  It's the other way around: load-extension is the new thing, and
> you should use it in preference to a dynamic-link/dynamic-call combo.
> However, dynamic-link and dynamic-call are not deprecated since they
> are useful on its own.
>
> Apparently some docs about this are confusing.  Can you say where you
> learned that load-extension is deprecated?

My bad memory perhaps?  :>

What's the thing that preceeded load-extension then?  You and I had a
discussion a while back about it, and about how the default
assumptions it was making were causing trouble, and that's when you
changed things -- I think perhaps I'm remembering
scm_register_module...

-- 
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
GPG=1C58 8B2C FB5E 3F64 EA5C  64AE 78FE E5FE F0CB A0AD

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Re: [Fwd: guile-1.7.x and load-extension]

[Marius Vollmer]

Rob Browning <rlb@defaultvalue.org> writes:

> Marius Vollmer <mvo@zagadka.ping.de> writes:
> 
> > Nooo!  It's the other way around: load-extension is the new thing, and
> > you should use it in preference to a dynamic-link/dynamic-call combo.
> > However, dynamic-link and dynamic-call are not deprecated since they
> > are useful on its own.
> >
> > Apparently some docs about this are confusing.  Can you say where you
> > learned that load-extension is deprecated?
> 
> My bad memory perhaps?  :>
> 
> What's the thing that preceeded load-extension then?  You and I had a
> discussion a while back about it, and about how the default
> assumptions it was making were causing trouble, and that's when you
> changed things -- I think perhaps I'm remembering
> scm_register_module...

Yes, that could be.  'load-extension' came at about the time the
automatic loading of shared libraries as modules was deprecated (and
removed in 1.7).  It was meant to be used instead of the more explicit

    (dynamic-call ... (dynamic-link ...))

combo.

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