Please see Python code, then the Perl equivalent:

import re
r = re.compile(r'(?P<A> a (?P<B> b))', re.X)
m = r.search('ab')
for k in m.groupdict():     
    print k, '=>', m.group(k)    # 'A => ab'             
                                 # 'B => b'
print m.group('A')               # 'ab'
print m.group('B')               # 'b'
[download]

Perl equivalent:

'ab' =~ /(?<A> a (?<B> b))/x;
print "$_ => $+{$_}\n" for (keys(%+));    # 'A => ab'
                                          # ... nothing, thats it
print "$+{'A'}\n";                        # 'ab'
print "$+{'B'}\n";                        # 'b'
[download]

Perl doesn't enumerate all the keys if a named capture is nested within another. But it it clearly holds the correct value 'b' with the correct key 'B' in the hash. Is this a "feature" or a bug? ;)

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.