| Subject: | Operator-precedence mistake in platform checks |
| Date: | Tue, 23 Jan 2018 23:47:45 -0500 |
| To: | <bug-Convert-BinHex [...] rt.cpan.org> |
| From: | Daniel Macks <dmacks [...] netspace.org> |
The following is used in several places (binhex.pl, debinhex.pl, BinHex.pm) to determine if the platform is a certain string:
if ($^O||'' eq "MacOS") { # binhex.pl line 123
The intent is probably to have a fallback if the usual perl variable is not set, which should be interpreted as:
if (($^O||'') eq "MacOS") { # intended meaning
and only be true on MacOS platform. But || binds more weakly than eq, so it is instead acting as:
if ($^O||('' eq "MacOS")) { # actual meaning
and is true on all platforms where $^O is nonzero. That means code such as Mac::Files::FSpGetCatInfo is run on non-Mac platforms and fails badly. Adding parens as in the "intended meaning" example seems to resolve it. A cleaner way (self-documenting the fallback, and remembering that treating a string as a boolean isn't the same as checking whether it is set) is:
if (defined $^O and $^O eq "MacOS") {
dan
--
Daniel Macks
dmacks@netspace.org