Well, it does work, as local not only squirrels away the
old global value, but sets it to undef for the loop.
However, upon writing some example code, I noticed a
strange difference between two global variables, $/
and $^T. Both mean something, and always have values
(and are thus defined) at the start of a script. However,
$/ gets set to undef when used with a local, while $^T
gets set to "0". [Luckily, $/ does not get set to 0,
or my examples would not work. :)] Anyone know why
$^T acts like that? Here's the code, and the results.
This is perl 5.005_03, FWIW.
$MY = 1;
$LOC = 1;
{
local $LOC; local $LOC2; local $/; local $^T;
my $MY; my $MY2;
printf "LOC defined: %s\n", defined $LOC ? "YES" : "NO";
printf "LOC2 defined: %s\n", defined $LOC2 ? "YES" : "NO";
printf "IRS defined: %s\n", defined $/ ? "YES" : "NO";
printf "TIME defined: %s\n", defined $^T ? "YES" : "NO";
printf "MY defined: %s\n", defined $MY ? "YES" : "NO";
printf "MY2 defined: %s\n", defined $MY2 ? "YES" : "NO";
print " LOC=$LOC, LOC2=$LOC2, TIME=$^T, IRS=$/, MY=$MY, MY2=$MY2\n"
+;
}
print "AFTER LOOP:\n";
print " LOC=$LOC, LOC2=$LOC2, TIME=$^T, IRS=$/, MY=$MY, MY2=$MY2\n";
Which produces:
LOC defined: NO
LOC2 defined: NO
IRS defined: NO
TIME defined: YES
MY defined: NO
MY2 defined: NO
LOC=, LOC2=, TIME=0, IRS=, MY=, MY2=
AFTER LOOP:
LOC=1, LOC2=, TIME=960648360, IRS=
, MY=1, MY2=
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[d/l]
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Since $^T is the time in seconds since the script began, I would be surprised if *anything* ever automatically set it to undef. Zero seems like a pretty good default to me, so I'll just make the assumption that somewhere in perlguts, someone agreed with me.
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