On 2006-07-16, Avi Kak <[EMAIL PROTECTED]> wrote:
> Folks,
>
> Does regular expression processing in Python allow for executable
> code to be embedded inside a regular expression?
>
> For example, in Perl the following two statements
>
> $regex = qr/hello(?{print "saw hello\n"})mello(?{print "saw
> mello\n"})/;
> "jellohellomello" =~ /$regex/;
>
> will produce the output
>
> saw hello
> saw mello
>
> Is it possible to do the same in Python with any modules that come
> with the standard distribution, or with any other modules?
You can use sub and make the replacement pattern a function (or any
"callable" thing) and it gets called back with the match object:
import re
def f(mo):
if "hello" in mo.groups():
print "saw hello"
if "mello" in mo.groups():
print "saw mello"
re.sub(r'(hello)(mello)', f, "jellohellomello")
Actually I didn't know you could do that in Perl. The time I've found
this useful in Python is substitutions to convert e.g.
"background-color" into "backgroundColor"; a function turns the c into
C. I always assumed in Perl you would need to use eval for this, but
perhaps there is another way.
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