It'd help if you explained what parts you already do understand, so we don't have to repeat that. Do you know what qw() does? How about map? References? sub{}?
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Okay, now I'm nervous ;-) My reason for asking is purely academic--I'm trying to REALLY learn Perl (yes I have read the Llama book and am plowing through the Camel tome). However, instead of starting with what I don't understand, let me start with what I do (I do understand your first reply to this post and even much of the Linux article referenced).
It appears that in the first line:
my %hash = map { my $item = pop @$_; map { $_, $item } @$_ }
you are mapping a key and value to %hash from an array. Next, it looks like a string of "HELP" redirects flow to a sub (as does the last line "QUIT"...).
Now, what I don't understand, specifically, how are the keys and values being mapped into the hash (where are they coming from)? What does pop @$_ do (couldn't find @$_ explained anywhere)? How does the last bit on that first line work? map { $_, $item } @$_
Lastly, why are there square brackets bookending lines 2 and 3?
I may not be ready for this heady stuff, but I'm willing to try. Thanks merlyn.
Update:
Thanks to runrig and his reply. I get it in theory, but not in practice. Though it has encouraged a more thorough understanding of map. I'll look at this in a couple of months and probably get it fine. Thanks.
—Brad
"A little yeast leavens the whole dough."
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'Bookending' things with square brackets creates an array reference (see perldoc perlref). So in the outer map, for each bookended thing, $_ is set to that array reference. @$_ dereferences that array reference, so my $item = pop @$_ removes the last item from the array (which is the subroutine reference), and puts it in $item. Then in the inner map we loop over everything left in the array (all the multiple keys) and create key/value hash pairs out of our multiple keys where the value is the subroutine reference that we popped off in the first place.
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