I noticed this code today: 

# Read a text file, stripping leading and trailing whitespace
# and ignoring any lines starting with '#'
my $file = shift;
open(my $in, '<', $file) or die "error: open $file: $!";
my @lines = grep { s/^\s+//; s/#.*//; s/\s+$//; $_ } <$in>;
close($in);
for my $x (@lines) { print "x='$x'\n" }

[download]
It caught my eye because it seems stylistically dubious in that grep should be used to select from a list, while here it's being used to modify the list. It also contains a subtle bug in that lines consisting of a bald zero (0) will be erroneously discarded. Now, I could fix this bug with: 
my @lines = grep { s/^\s+//; s/#.*//; s/\s+$//; length($_) } <$in>;

[download]
or: 
my @lines = map { s/^\s+//; s/#.*//; s/\s+$//; length($_) ? $_ : () } 
+<$in>;

[download]
though I'm not especially happy with either of these. How would you do it?

In reply to A perverse use of grep by eyepopslikeamosquito

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