Foro - Perl en Español

1999akestaesmicadenaak1212990as

    Extend your pattern's legibility by permitting whitespace and comments.

These are usually written as ``the /x modifier'', even though the delimiter in question might not actually be a slash. In fact, any of these modifiers may also be embedded within the regular expression itself using the new (?...) construct. See below.

The /x modifier itself needs a little more explanation. It tells the regular expression parser to ignore whitespace that is neither backslashed nor within a character class. You can use this to break up your regular expression into (slightly) more readable parts. The # character is also treated as a metacharacter introducing a comment, just as in ordinary Perl code. This also means that if you want real whitespace or # characters in the pattern (outside of a character class, where they are unaffected by /x), that you'll either have to escape them or encode them using octal or hex escapes. Taken together, these features go a long way towards making Perl's regular expressions more readable. Note that you have to be careful not to include the pattern delimiter in the comment--perl has no way of knowing you did not intend to close the pattern early. See the C-comment deletion code in the perlop manpage.