grep returns aliases, but assignment (to @m) makes copies. You can not modify the grep results directly though, so you need to do something like take a reference, pass it to a (naughty) sub, or make a modifiable alias in order to modify the alias, and not just a copy thereof:

@l = ( "a", "b", "c" );
$_ = "z" for grep /a/, @l;
print @l;
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Prints "zbc".

example (here map works on the list returned by grep before it's assigned to an array):

@l = ( "a", "b", "c" );
@m = map {s/a/z/} grep /a/, @l;
print @l;
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Enjoy,
-- Mickey

#!/usr/bin/perl

# Yo, I'll tell you what I want, what I really really want, 
# So tell me what you want, what you really really want, 
# I'll tell you what I want, what I really really want, 
# So tell me what you want, what you really really want, 
# I wanna, I wanna, I wanna, I wanna, 
# I wanna really really really wanna zigazig ha. 


@l = ( "a", "b", "c" );
*m = &{sub {\@_}} (grep /a/, @l);
$m[0] = "z";
print "@l\n";
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I was excited by your answer at first because I thought it was that trick I saw for making aliases, and which I can never remember. ;-)

But then I realized that you're using a glob, which means you could simply write

@l = ( "a", "b", "c" );
*m = \@l;
$m[0] = "z";
print "@l\n";
[download]

We're building the house of the future together.

Yes, you're right. My reply was a bit tongue-in-cheek - the OP asked why his grep aliasing example "didn't work" and I resolved to beat it into submission ;)

There's a slight difference though. *m = \@l; aliases the entire array object. The sub {\@_} trick creates a new array object containing scalar elements which are aliased to memberes in @l matching /a/ (in OP's example it contains only one element aliased to the first element in @l - "a").

What, nobody remembers grep in grep BLOCK LIST usage?!

@l = qw( a b c );

#  '@m' just as well be '()' unless used later, but then I personally
#  would be doing C</a/ and $_ = 'z' for @l;>.
@m =  grep { /a/ and $_ = 'z' } @l;

print @l;
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And a different take on reply from Sidhekin ...

/a/ and $_ = 'z' for @l;
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~Nov 26 2006, 7p US-EDT: Changed '@p' to '@l'.

If an array of references suffices then:

use strict;
use warnings;

my @l = ( "a", "b", "c" );
my @m = map {\$_} grep /a/, @l;
${$m[0]} = "z";

print @l;
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seems to do what you want:

zbc
[download]