| Subject: | Surprising 'Build clean' side effect in copied project directory |
This one took a long time for me to figure out... Under specific circumstances, 'Build clean' (or any Build actions for that matter) can operate in the wrong directory. Try this:
% cd MyProject
% perl Build.PL
% Build
% cd ..
% cp -r MyProject MySimilarProject
% cd MySimilarProject
% Build clean
This scenario arises because I'm in the habit of starting a new module by copying an older, similar one and editing instead of starting fresh with h2xs.
The clean action in the example above runs in the "MyProject" directory, which is unexpected. This is because the $start_dir is recorded in the Build file. The principle of least surprise suggests that Build should work like MakeMaker in that it works on the current directory, not on an absolute directory.
A workaround is to always 'Build realclean' in a project directory before copying or moving it.
A possible solution is to desist from storing the $start_dir and instead have Build chdir() to it's own location by looking at $0.
A similar issue would arise in the @INC array stored in Build, in which "." is translated into an absolute path. In this case, a workaround would be to leave the @INC paths unchanged. The relevant line of code is:
$_ = File::Spec->rel2abs($_);
in the print_build_script() method.