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copied!<p>You seem to have a misconception about how <code>=~</code> works. <code>=~</code> is a binding operator that associates a variable with a regexp operator. It does not do any assignment.</p> <p>The regexp operators all work by default with the topic variable <code>$_</code>, so <code>s/foo/bar/;</code> is the same as <code>$_ =~ s/foo/bar/;</code>. No assignment occurs. The topic variable is transformed.</p> <p>The case is analogous when operating on any other variable. <code>$var =~ s/foo/bar/;</code> transforms <code>$var</code> by replacing the first instance of <code>foo</code> with <code>bar</code>. No assignment occurs.</p> <p>The best advice I can give you is to write Python in Python and Perl in Perl. Don't expect the two languages to be the same.</p> <p>You could do like DVK suggests and write a subroutine that will reproduce the substitution behavior you are used to.</p> <p>Or you could try some idiomatic Perl. Based on your expressed desire to apply multiple transformations in one line, I've provided a couple examples you might find useful.</p> <p>Here I use a <code>for</code> loop over one item to topicalize <code>$var</code> and apply many hard-coded transformations:</p> <pre><code>for( $var ) { s/foo/bar/; s/fizz/buzz/; s/whop/bop-a-loo-bop/; s/parkay/butter/; s/cow/burger/; } </code></pre> <p>Or maybe you need to apply a variable group of transforms. I define a subroutine to loop over a list of array references that define old/new transformation pairs. This example takes advantage of Perl's list oriented argument processing to handle any number of transformations.</p> <pre><code>my $foo = transform( 'abcd' => [ 'a', 'b' ], [ 'bb', 'c' ], [ 'cc', 'd' ], [ 'dd', 'DONE' ], ); sub transform { my $var = shift; for (@_ ) { my ($old, $new) = @$_; $var =~ s/$old/$new/; } return $var; } </code></pre> <p>Finally a bit of messing about to provide a version of transform that modifies its first argument:</p> <pre><code>my $foo = 'abcd'; transform_in_place( $foo => [ 'a', 'b' ], [ 'bb', 'c' ], [ 'cc', 'd' ], [ 'dd', 'DONE' ], ); print "$foo\n"; sub transform_in_place { for my $i (1..$#_ ) { my ($old, $new) = @{$_[$i]}; $_[0] =~ s/$old/$new/; } } </code></pre> <p>For my own project I'd probably use one of the first two options depending on the needs of the particular problem.</p>

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