#9208: Add PKG_CONFIG_PATH to sage-env so programs like matplotlib link
properly.
----------------------------+-----------------------------------------------
Reporter: drkirkby | Owner: drkirkby
Type: defect | Status: needs_review
Priority: major | Milestone: sage-4.4.4
Component: build | Keywords:
Author: David Kirkby | Upstream: N/A
Reviewer: | Merged:
Work_issues: |
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Comment(by drkirkby):
Replying to [comment:8 jason]:
> Replying to [comment:7 drkirkby]:
> > I meant to overwrite the patch when I corrected the spelling, but
forgot, so there is now 9208.2.patch.
> >
> > Are you suggesting this gets reviewed and incorporated into Sage and
you write another patch which rewrites sage-env if Sage is moved?
>
> Not sage-env. See #9210 for the patch I talked about.
>
> > If so, then this still needs reviewing.
> >
>
> Yes. Since I practically had the same patch, but you beat me to posting
it, I think the review will be easy.
>
> I didn't check for the existence of PKG_CONFIG_PATH, though. In what
situation will we not want to overwrite that variable?
>
>
I must admit, I did consider whether it was appropriate to simply
overwrite PKG_CONFIG_PATH and ignore whatever the user puts. But I could
see some benefits in allowing the user to set this.
* If I wanted to use a later version of a library that Sage has, I would
be able to do so by putting my libraries in a location of my choosing, and
let Sage find them first.
* in some cases one might have libraries that Sage lacks, but one wants
to use with programs like matplotlib. (GTK could be an exmaple of that).
Another possibility, is to prepend Sage's path to PKG_CONFIG_PATH, so
things in Sage are found first, but others that exist on the system will
be found too, since according to the man page of pkg-config on Solaris:
{{{
User Commands pkg-config(1)
NAME
pkg-config - return meta information about installed
libraries
<SNIP>
PKG_CONFIG_PATH A colon-separated (on Windows,
semicolon-separated) list of direc-
tories to search for .pc files. The
default directory is always searched
after searching the path specified
by PKG_CONFIG_PATH. The default
value of PKG_CONFIG_PATH is
libdir/pkgconfig, where libdir is
the lib directory where pkg-config
is installed. On Solaris systems,
libdir is /usr/lib.
}}}
PKG_CONFIG_PATH is a colon separated list of paths. Simply overwriting
PKG_CONFIG_PATH would make it impossible for someone to get matplotlib to
use their version of GTK for example in /usr/local, if they wanted that.
Doing something about the issue with PKG_CONFIG_PATH is clearly better
than doing noting at all, but what is best is a bit subjective. I don't
have a strong opinion as to what is best.
The solution here is the most flexible, as it gives the user complete
control, but that flexibility does come at some risk. I suspect the risk
is quite small, as I doubt many people set PKG_CONFIG_PATH themselves. If
they do, they probably know what they are doing :)
Dave
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9208#comment:9>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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