Re: Library file locations

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

Tapio Kelloniemi <spam18@thack.org> writes:
> I don't think that /usr/local is very non-standard location for installing
> software. Actually if I daily used a system where there is a package manager 
> provided by the distro, I would not install programs compiled by myself in the 
> /usr hierarchy. You know better than I what happens if a sysadmin installs a 
> package in /usr which overwrites a file already installed by the distro. 
> Therefore it is good practice to install under /usr/local to prevent messing 
> up the system's package management, and for other reasons as well.
> This is why /usr/local should be supported automatically or at least easily.
> What comes to setting ADA_PROJECT_PATH in a Makefile:
> Imagine that I have installed some Ada library under /usr/local (the distro 
> provides a precompiled binary, but I want to enable a feature X required by 
> package A). Then I compile A. If the library and the package A were written in 
> C, I would do the following to compile A:
> ./configure && make && make install
>
> As they are written in Ada, I do:
> ./configure --with-additional-ada-project-path=/usr/local/share/ada/adainclude
>
> And what if the configure script does not support the above
> mentioned option?  I would have to edit Makefiles, possibly run
> automake, etc. If the compilation process happens to be automated, I
> must write some nasty sed scripts to do the job.

Ada programs do not normally require configure scripts.  I tend to
think of configure scripts as symptoms of bad engineering.  Automake?
Why use automake?  KISS!

ADA_PROJECT_PATH=/usr/local/share/ada/adainclude make

is sufficient and addresses your concern that "/usr/local should be
supported automatically or at least easily" - for easy it is, indeed.
And yes, if it's under /usr/local, then it's outside of the distro's
responsibility - "someone else's problem" is indeed "the
administrator's problem".

A second easy way to support /usr/local is:

echo "ADA_PROJECT_PATH=/usr/local/share/ada/adainclude" >> /etc/environment

which is, of course, an implementation of a local (system-wide) policy
decided by the administrator and not the distro.

-- 
Ludovic Brenta.