Re: Creating a partial library

[John Calcote]

Hi Justin,

On 2/2/2010 6:39 PM, Justin Seyster wrote:

> I'm pretty sure that making the framework a convenience library is my
> ideal solution: the plug-in author will be able to distribute a single
> shared object without any non-standard dependencies.  However, I read
> that Automake does not allow installing a convenience library.  I
> verified that a regular static library (not specified with
> noinst_LTLIBRARIES) definitely does not work: the resulting .a file is
> not position independent and won't link into a plug-in.  I don't want
> to use noinst_LTLIBRARIES, though, for the simple reason that I want
> to be able to install the library!
>    

A convenience library is so named because it provides the convenient 
effect of encapsulating a set of code that multiple products can link to 
within a package. That's it's only purpose - to bundle up code that can 
then be linked into multiple products within your package. Hence, it's 
not intended to be consumed outside of your package.

You're correct in understanding that a non-libtool (*_LIBRARY) product 
is a non-PIC static library, and you are also correct in understanding 
that they can't be linked into a shared library for this reason.

You can build installed LTLIBRARIES as shared libraries, static 
libraries, or both, and you can configure the default in your 
configure.ac file, but unfortunately, I haven't found a way to make this 
default apply only to a subset of the installed LTLIBRARIES built within 
a package. It appears to be all or nothing. Furthermore, it's just a 
default. The user can always override your defaults with command line 
options to configure. Personally, I think it would be a nice enhancement 
to Automake to allow you to specify that you want specifically to build 
an installed static (only) LTLIBRARY that can then be linked into a 
shared library in another package. The Libtool manual states that 
there's no good reason for doing this, but you and I have both 
encountered situations when we want to do just this.

For the reasons outlined above, automake doesn't allow you to build a 
convenience library and install it. The only way to build a convenience 
(PIC-based static only) library is to use the "noinst" prefix. But 
libtool can be used to manually install a convenience library, so you 
could use libtool to do this in an install-exec-local rule in the 
Makefile.am file that builds (for instance) libhello.a (untested):

install-exec-local:
        libtool --mode=install ./install-sh -c libhello.a 
$(DESTDIR)$(lib)/libhello.a

This example came from the libtool manual (modified slightly for 
Automake context).

Regards,
John