Trying to come up with a way to write cross-platform, shell safe perl
one-liners was causing me to lose sleep. So I've given up one trying to
write One Unified One Liner and instead took a page from the perl core test
suite's t/test.pl run_perl().
There is now a perl_oneliner() method which given some perl code and
switches will generate a safe one liner. Overrides have been put in
MM_Win32, MM_Unix and MM_VMS to do the escapes and quoting appropriate for
that platform. After playing with it some, I added suport for newline
escaping (which could probably be improved to use multiple -e's) and
stripping of leading/trailing newlines.
It doesn't do everything, just enough to handle the code I've thrown at it
so far.
If the VMS and Win32 folks could examine their versions of perl_oneliner()
to make sure I got it right.
Also, we need one for MacOS Classic.
The end result? Instead of this:
return <<'MAKE_FRAG';
dist : $(DEFAULT)
$(NOECHO) $(PERL) -le "print 'Warning: Makefile possibly out of date with
$(VERSION_FROM)' if -e '$(VERSION_FROM)' and -M '$(VERSION_FROM)' < -M '$(MAKEFILE)';"
MAKE_FRAG
you can do this:
my $date_check = $self->perl_oneliner(<<'CODE', ['-l']);
print 'Warning: Makefile possibly out of date with $(VERSION_FROM)'
if -e '$(VERSION_FROM)' and -M '$(VERSION_FROM)' < -M '$(MAKEFILE)';
CODE
return sprintf <<'MAKE_FRAG', $date_check;
dist : $(DEFAULT)
$(NOECHO) %s
MAKE_FRAG
so the code formatting is natural and you don't have to worry about quoting.
The end result in the Makefile is icky:
dist : $(DIST_DEFAULT)
$(NOECHO) $(PERLRUN) -l -e 'print '\''Warning: Makefile possibly out of
date with $(VERSION_FROM)'\''\
if -e '\''$(VERSION_FROM)'\'' and \
-M '\''$(VERSION_FROM)'\'' < -M '\''$(MAKEFILE)'\'';'
but its more important that the MakeMaker code is easy to maintain than the
resulting Makefile.
The real win is that with the ability to generate portable one-liners, a
whole slew of duplicate method overrides in MM_VMS and MM_Win32 that are
just there to change quoting from ' to " go away.
So, if anyone has a little free time you can start running through the
MM_Unix code and replacing ad-hoc one-liners with perl_oneliner() generated
code.
--
Michael G. Schwern <[EMAIL PROTECTED]> http://www.pobox.com/~schwern/
Perl Quality Assurance <[EMAIL PROTECTED]> Kwalitee Is Job One
"Please hold while reality is adjusted to match my ideal world."
-- njt
