Hello QM,

I assume you’re referring to the comma operator in scalar context, which “evaluates its left argument, throws that value away, then evaluates its right argument and returns that value.” (perlop#Comma-Operator).

A quick Google search found this 2010 discussion: http://stackoverflow.com/questions/2200759/when-is-perls-scalar-comma-operator-useful, in which Jonathan Feinberg suggests that the scalar context comma operator is provided for two reasons:

  1. As a hangover from C, because Perl was originally derived from C.
  2. Because it’s useful in cases where you want to execute two or more statements in a syntactic context that allows only a single statement.

Here’s a contrived example:

19:49 >perl -wE "for (my ($i, $j) = (1, 5); $i <= 5; ++$i, --$j) { say
+ abs($i - $j); }"
4
2
0
2
4

19:49 >

[download]

Of course, it is quite possible to re-structure that loop without resorting to use of the comma operator in scalar context. But in Perl’s spirit of TMTOWTDI, the ++$i, --$j syntax is provided for convenience. That’s my take on it, anyway.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re^4: hangman game by Athanasius
in thread hangman game by mbgbioinfo

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