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Re^5: What is true and false in Perl?

by jdporter (Canon)
on Oct 18, 2012 at 15:25 UTC ( #999756=note: print w/replies, xml ) Need Help??


in reply to Re^4: What is true and false in Perl?
in thread What is true and false in Perl?

The same thing tobyink and tye said, though more obtusely and snarkily.

Here's another example:

tie my $var, 'Some::BlackBox::Module'; $var = "45"; if ( $var ) { print "var is true\n" } # doesn't print! WTF?

The mere fact that an expression evaluates to a true value in scalar context doesn't mean it is true.

tie and overload are among the user-accessible features which can muddy the true/false waters.

An example like this should make the principle more obvious:

my $obj = ObjectWithLotsOfOpaqueStructure::AndLotsOfHiddenState->new( -use_overloading => 1, ); if ( $obj ) { print "obj is 'true'.\n"; # What does this even mean? # Maybe obj is an iterator with another available item? }

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[Corion]: Ah, so this is homework? Then most likely, you should review your course material closer. It would greatly surprise me if the course material wouldn't mention the topics that will be used in the homework...
[Corion]: I already showed you the simple regex to match the last part of a string without a comma in it
[Tux]: Corion++ hippo++
[ovedpo15]: it isn't homework. its a module I use at work. The process to add additional module isn't worth it. p.s never heard a university course which teach perl
[marto]: there are many, to this day.
[ovedpo15]: @Corion Yes I use the regex you showed me. its very good regex. although now i need to know that substring unit that comma
marto mad corrections to one around 18 months ago
[ovedpo15]: my code checks the value after that comma, if it isn't valid it will remove it. so I would like to remove the substring after that comma meaning getting the string before comma.
[hippo]: Are you sure that Text::CSV_XS isn't already installed at your work? It's such a useful module that it might well be there.
[marto]: pointing out the advantages of cpan modules is well worth in, as both developer and $client/$company benefit greatly

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