Re: make subroutine that takes expression as implicit block as first arg

You can accomplish your task using Prototypes. In fact, from the linked documentation,

here's a reimplementation of the Perl grep operator:
sub mygrep (&@) { my $code = shift; my @result; foreach $_ (@_) { push(@result, $_) if &$code; } @result; }
[download]

Update: Your example would be called as: print join ",", mygrep {$_ % 2 == 0} 0..10; Note the deviation from the proposed use case. I'd initially missed the spec for "automatically put [ting] it in an implicit block"

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Re^2: make subroutine that takes expression as implicit block as first arg by oko1 (Deacon) on Aug 13, 2010 at 19:54 UTC
That won't work, for the proposed case: `Type of arg 1 to main::mygrep must be block or sub {} (not numeric eq +(==)) at /tmp/mygrep line 7, near "10)" Execution of /tmp/mygrep aborted due to compilation errors.` [download] Perhaps something like this? `sub mygrep { my $s = "grep $_[0]"; eval $s; } print for mygrep('$_ % 2 == 0, 0..10'); # :-)` [download] -- "Language shapes the way we think, and determines what we can think about." -- B. L. Whorf	[reply] [d/l] [select]
Re^3: make subroutine that takes expression as implicit block as first arg by kennethk (Abbot) on Aug 13, 2010 at 20:01 UTC
I added a use case, as this sort of structure is a bit sensitive - perl apparently interprets the OP proposed use case as an anonymous hash because parentheses are present. When I was going through a clever phase, I played a bit with prototypes, and decided they are generally more trouble than they are worth. IMHO, of course.	[reply]


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