Oh keepers of the faith...

If I want to use a user input string as a regular expression, what checks should I make? I think I only need to escape / and new line chars.

Obviously, it would be pointless to use quotemeta here :), but are there any other characters that I really should escape before using in eval?

Er, this is the sort of thing I was thinking of: 

$input = '...'; # input from user
$value = '...'; # String I want to test to see if $input matches

# escape s/delimiter/
$input =~ s|/|\/|gs;

# strip new lines - not expected in input anyway 
$input =~ s/\n//gs;

my $match;
eval q{
  $value =~ /($input)/; # try match
  $match = $1;          # assign here because of local scope?
};
if ($@ ne '') {
  # error because invalid reg exp sent
}
else {
  if ($match) {
    # regexp matched
  }
  else {
    # reg exp not matched
  }
}

[download]
I *think* this is sound, but was wondering if anyone can drill any holes in it b4 I go any further down this route...

cLive ;-)

PS - perhaps I should wait and do this in Parrot instead? :)

In reply to Checking user input on dynamic regular expressions by cLive ;-)

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