Is it possible to use a variable in place of the expression or block of grep? Am I missing something simple or is this simply illegal?

With the simple fragment below, I would like to get a result of 1,2 for both greps but I get all elements on the second. Btw, I get the same results from the expression version: "grep $var, @arr".

use strict; use warnings;

my @arr = (1, 2, 3, 4, 5);
my $pat = '$_ < 3';
my @res;

@res = grep {$_ < 3} @arr;
print "Literal:\t@res\n";

@res = grep {$pat} @arr;
print "Variable:\t@res\n";

[download]

Of course, this is just a test script. The real thing builds the grep pattern in several steps and searches a two-dimensional array. I could do all this differently but the most obvious alternative would be a long list of if statements.

In reply to grep { $var } @arr by igelkott

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.