Re^3: sub that sets $

Which means that while ($z = prompt "") { will set $_ and $z. This is a bad idea. What if the code is used in an inner loop? when the outer loop uses $_ for example?

Yes, that is a nuisance. I'm working on overcoming that problem, but it's difficult: Perl never quite gives you enough context information to detect the assignment. :-(

Comment on Re^3: sub that sets $_

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Re^4: sub that sets $_ by TheDamian (Vicar) on Jun 29, 2005 at 00:54 UTC
On further investigation, it appears that you can tell the two contexts apart using the Want module. Specifically, `want('BOOL')` knows the difference. For example: `my $flipflop = 0; sub foo { use Want qw(want); print 'not ' if !want 'BOOL'; print "bool\n"; return $flipflop=!$flipflop; # alternate true and false } for (1..3) { while (foo() ) { # print "here 1\n"; } while ($answer = foo() ) { # print "here 2\n"; } }` [download] Unfortunately, under 5.8.3 I get bus errors if there I uncomment the `print` statements, or if there is anything in the `while` blocks. `:-(`	[reply] [d/l] [select]

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Re^4: sub that sets $_
by TheDamian (Vicar) on Jun 29, 2005 at 00:54 UTC

Want

want('BOOL')

my $flipflop = 0;

sub foo {
    use Want qw(want);

    print 'not ' if !want 'BOOL';
    print "bool\n";

    return $flipflop=!$flipflop;   # alternate true and false
}

for (1..3) {
    while (foo() ) {
        # print "here 1\n";
    }
    while ($answer = foo() ) {
        # print "here 2\n";
    }
}
[download]

Unfortunately, under 5.8.3 I get bus errors if there I uncomment the print statements, or if there is anything in the while blocks. :-(

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