Re^3: Regexp substitution using variables

> does not (at least to my eyes) show what the difference is between them.

you are comparing

perlre#(?^alupimnsx)
"... for the remainder of the pattern or the remainder of the enclosing pattern group (if any)..."
perlre#(?^aluimnsx:pattern)
"... this is for clustering ..."

in your example there is no difference, but in the second approach with pattern the reach of modifiers is limited to the group.

  DB<24> p 'xX' =~ /(?i:X)X/
1
  DB<25> p 'xX' =~ /(?i:X)x/

  DB<26> p 'xX' =~ /(?i)Xx/
1
  DB<27>
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery}