Script2: 
#my $var = "xxx\n";
my $var="zzz\n" unless defined($var);
print $var;

[download]
Name "main::var" used only once: possible typo at unlesstest.pl line 2
+.
zzz

[download]

That happens because before doing the assignment, the right-hand-side of the statement must be resolved. So, a global variable $var is created, and then masked immediately by a lexical variable $var. These variables are not related, and the warning is about the global one, which isn't accessible any more, since it is masked immediately by the my variable.

In reply to Re: conditional definition of variables by shmem
in thread conditional definition of variables by stephanm

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