Re: 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
[download]

Cheers Rolf

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Re^2: Detecting if a string is a regular expression by AnomalousMonk (Archbishop) on Jan 10, 2013 at 23:40 UTC
... 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` [download]	[reply] [d/l] [select]
Re^3: Detecting if a string is a regular expression by LanX (Saint) on Jan 11, 2013 at 00:06 UTC
yeah I noticed, but normally I prefer the more obvious syntax. (the m is superfluous too =) Cheers Rolf PS: I know someone will show us now benchmarks demonstrating that at least 3 and half processor cycles are waisted this way ... ;)	[reply]