in reply to Generating complex LDAP queries with Perl

    while (my $cond = shift) {
        $filter = "($op $filter $cond)" if defined $cond;
    }

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The while conditional will exit the loop if $cond is false or undefined so the subsequent test for defined is redundant, $cond will not be undefined inside the loop.   Note that if $cond also contains "0" or "" it will exit the loop.

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Re^2: Generating complex LDAP queries with Perl
by grinder (Bishop) on Jul 18, 2009 at 09:34 UTC

    Just to situate the historical context, I added the if defined $cond much later on in the piece, when I added the IGNORE() function to change an AND() or an OR() into a no-op.

    The idea was to ensure that "valid1", "valid2", undef, "valid3" produces a syntactically correct query, without a fourth half-baked conditional creeping in there.

    But you know what? You're absolutely correct. Given the above and the following:

    sub _joiner {
    my $op = shift;
    my $filter = shift;
    while (my $cond = shift) {
        $filter = "($op $filter $cond)";
    }
    return $filter;
}

my $filter = AND(
    "(a=1)",
    IGNORE(
        "(b=1)",
        "(b=2)",
    ),
    "(c=1)",
);

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    It does indeed produce (& (a=1) (c=1)). Thank-you very much for this insight, I appreciate it.

    • another intruder with the mooring in the heart of the Perl

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In Section Cool Uses for Perl