[CMake] out of source command line flag

[Alan W. Irwin]

On 2009-09-05 09:38+0200 Hendrik Sattler wrote:

> The problem with how giving the build-dir/source-dir to cmake is currently too
> much dependent on other conditions:
>  cmake [options] <path-to-source>
>  cmake [options] <path-to-existing-build>
>
> The first only is true if no CMakeCache.txt exists there. This was actually a
> bad choice to have that as only possibility.
> Being able to do an out-of-source build even if there was a previous in-source
> build would be much appreciated.

I second that motion to drop the <path-to-existing-build> interpretation
(subject to policy protection, of course, assuming there is at least some
legitimate use case for <patch-to-existing-build>.)

CMake newbie's natural tendency seems to be to try an in-source build first.
Thus, I cannot count how many times PLplot and FreeEOS users out-of-source
build experience has been silently messed up by their first build attempt
which was in source. I have never heard of users actually using the
<path-to-existing-build> interpretation except by mistake.  However,
assuming there is some legitimate use case, I suggest you make a POLICY to
drop the <path-to-existing-build> interpretation. I would be happy to adopt
such a policy for my different software projects simply to drop the volume
of necessary advice to first-time users who keep falling into the trap of
using <path-to-existing-build> by mistake.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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Linux-powered Science
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