Re: Detecting if a string is a regular expression

[LanX]

in reply to Detecting if a string is a regular expression

> Is there some quick and dirty way to detect is a string is a pure string, or if it is a regular expression.

no, IMHO any $string can be used as a valid regex like in m/$string/ w/o syntax error.

but if you need a regex datatype to distinguish $scalars use qr// to generate them.

  DB<106> $s='abc'
 => "abc"
 
  DB<107> $r=qr/abc/
 => qr/abc/
 
  DB<108> ref $r eq 'Regexp'
 => 1
 
  DB<109> ref $s eq 'Regexp'
 => ""
  
  DB<110> 'xabcx'=~m/$r/
 => 1
 
  DB<111> 'xabcx'=~m/$s/
 => 1

[AnomalousMonk]

... any $string can be used as a valid regex like in m/$string/ ...

... and you don't even need the  m// or  qr// incantation. The  =~ binding operator can do the trick:

>perl -wMstrict -le
"my $s = 'abc';
 ;;
 print 'match' if 'xabcx' =~ $s;
 print 'match' if 'xabcx' =~ 'abc';
"
match
match

[LanX]

yeah I noticed, but normally I prefer the more obvious syntax. (the m is superfluous too =)

PS: I know someone will show us now benchmarks demonstrating that at least 3 and half processor cycles are waisted this way ... ;)