On 07/27/2010 03:08 PM, Eric Blake wrote: > On 07/27/2010 02:58 PM, Stefano Lattarini wrote: >> +# Let user choose which version of autoconf to use. >> +AUTOCONF=${AUTOCONF-autoconf} >> + > > I'm used to this variant, with less typing: > > : ${AUTOCONF=autoconf} > > But your way works, too. Huh, I just realized that: : ${var=val} might be less efficient, if $var is already defined and contains globbing characters. To avoid wasting time on (unnecessary) file name expansion, it is faster to use : "${var=val}" even though both variants should (normally) have the same end result. In particular, on cygwin, doing globs can cause a side effect - if you ever cause a glob() to take place on a string containing a backslash, cygwin will warn on the console (but thankfully not pollute stderr) about your potential use of non-POSIX filenames. The bash-completion package applied several patches earlier this year to avoid globs, in part because of that cygwin side-effect. I should probably document that in the autoconf manual. -- Eric Blake eblake@xxxxxxxxxx +1-801-349-2682 Libvirt virtualization library http://libvirt.org
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