Re: regex s/// using hash

This seems to be a misleading (yet usefull) feature. it means that (${code}) isn't an "always true" assertion. But is it reliable enough to be used?

In (?(cond)|...), cond is not a regexp. While the syntax is similar, ?{code} has a different meaning there than in regexs.

In regexs, (?{code}) always matches. The return value is stored in $^R.

In (?(?{code})|...), (?{code})'s return value is used to determine which sub-regexs to use.
But is it reliable enough to be used?

Yes, it's reliable. The only catch is that these blocks are closures, so you can run into problem when you use lexical (my) variables declared outside of the regex in these blocks. I always use package (our) variables. If you have a lexical variable you don't want to convert, you could always create an alias to it.
```
our %pkg_hash; local *pkg_hash = \%lex_hash;
[download]
```
You seem to have problems deciding whether the keys are strings or regexs. Either way, your snippets are buggy. If they're strings, your 2nd and 3rd snippet should be
```
my $re = join '|', map quotemeta, keys %dict;
s/($re)/$hash{$1}/g;
[download]
```
```
use Regexp::List qw( );
my $re = Regexp::List->new()->list2re(keys %dict);
s/$re/$hash{$1}/g;
[download]
```
quotemeta converts strings to regexs, and Regexp::List works with strings (while Regexp::Assemble works on regexs).
If the keys are regex, your snippets won't work except for the simplests of regexs (those without any metachars) because you won't be able to lookup the appropriate hash entry in the replace expression.

Comment on Re: regex s/// using hash Select or Download Code

Replies are listed 'Best First'.
Re^2: regex s/// using hash by oha (Friar) on Oct 16, 2007 at 13:48 UTC
i'm not using `(?(cond)\|..)` but `(? (?{code}) \| (?!) )` i'm also a bit confused about the closures: being used in scope those regexp aren't returned so i can't see side-effect of using our or my, what am i missing? Nice, i was looking for Regexp::List but i found Regexp::Assemble, i thought i was recalling wrongly. Oha	[reply] [d/l] [select]
Re^3: regex s/// using hash by ikegami (Patriarch) on Oct 16, 2007 at 13:57 UTC
i'm not using `(?(cond)\|..)` but `(? (?{code}) \| (?!) )` Adding whitespace doesn't change what it is. i'm also a bit confused about the closures: being used in scope those regexp aren't returned so i can't see side-effect of using our or my, what am i missing A closure occurs when a sub persists longer than the scope in which it was created. The code in `(?{code})`, `(??{code})` and `(?(?{code})\|..)` is compiled into a sub. The regex persists beyond the scope in which it is created (to avoid needless recompiling of the regex), causing a closure. `sub func_lex { my ($var) = @_; '' =~ /(?{ print("$var\n"); })/; } sub func_pkg { our ($var) = @_; '' =~ /(?{ print("$var\n"); })/; } func_lex('foo'); # foo func_lex('bar'); # foo !!! func_pkg('foo'); # foo func_pkg('bar'); # bar` [download] Update: Added `func_pkg` to example.	[reply] [d/l] [select]
Re^4: regex s/// using hash by oha (Friar) on Oct 16, 2007 at 14:01 UTC
oh, i understood what you mean! so thinking about that, seems to me that the solution isn't working at all, unless some effort. thanks Oha	[reply]
Re^5: regex s/// using hash by ikegami (Patriarch) on Oct 16, 2007 at 14:06 UTC
Re^6: regex s/// using hash by oha (Friar) on Oct 16, 2007 at 14:12 UTC