Beefy Boxes and Bandwidth Generously Provided by pair Networks
We don't bite newbies here... much

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

I want to embed Perl code in my regex using (?{...}), so it's critical that the regex is compiled at compile time. I've gotten this to work without errors or warnings:

my $kind; my $REGEX = qr/ [A-Za-z][\w]* (?{$kind = 'IDENT';}) | (?: ==? | != | <=? | >=? ) (?{$kind = 'OP';}) | -?\d+ (?{$kind = 'INT';}) | \x27 ( (?:[^\x27] | \x27{2})* ) \x27 (?{$kind = 'STRING';}) | \S (?{$kind = 'OTHER';}) /xs;

However, I'd like to better organize the regex by splitting it into parts, then using those parts. This is what I'd like to do, but when I try, I get the error "Eval-group not allowed at runtime, use re 'eval' in regex". I think that the suggested workaround is bad practice, so I won't do it, but I don't understand why what I'm trying to do won't work since all the regex's involved use qr//. I've also tried using Readonly for the parts, but Perl still doesn't recognize that the parts I'm using will never change. Is there any other way to get $REGEX to compile at compile time while breaking it into parts?

my $IDENT = qr/ [A-Za-z][\w]* /xs; my $STRING = qr/ \x27 ( (?:[^\x27] | \x27{2})* ) \x27 /xs; my $OP = qr/ (?: ==? | != | <=? | >=? ) /xs; my $INT = qr/ -?\d+ /xs; my $kind; my $REGEX = qr/ $IDENT (?{$kind = 'IDENT';}) | $OP (?{$kind = 'OP';}) | $INT (?{$kind = 'INT';}) | $STRING (?{$kind = 'STRING';}) | \S (?{$kind = 'OTHER';}) /xs;

In reply to Re^2: Compiling Regular Expressions by johndeighan
in thread Compiling Regular Expressions by Anonymous Monk

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others having an uproarious good time at the Monastery: (6)
As of 2023-12-11 02:46 GMT
Find Nodes?
    Voting Booth?
    What's your preferred 'use VERSION' for new CPAN modules in 2023?

    Results (41 votes). Check out past polls.