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Date: Fri, 11 Jul 2014 08:18:09 -0700
From: Albert-Jan Roskam <fomcl@yahoo.com>
Subject: Re: How to decipher :re.split(r"(\(\([^)]+\)\))" in the example
To: Steven D'Aprano <steve@pearwood.info>, "python-list@python.org" <python-list@python.org>
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=0A=0A----- Original Message -----=0A=0A> From: Steven D'Aprano <steve@pear=
wood.info>=0A> To: python-list@python.org=0A> Cc: =0A> Sent: Friday, July 1=
1, 2014 11:04 AM=0A> Subject: Re: How to decipher :re.split(r"(\(\([^)]+\)\=
))" in the example=0A> =0A> On Thu, 10 Jul 2014 23:33:27 -0400, Roy Smith w=
rote:=0A> =0A>>  In article <mailman.11747.1405046292.18130.python-list@pyt=
hon.org>,=0A>> =A0 Tim Chase <python.list@tim.thechases.com> wrote:=0A>> =
=0A>>>  On 2014-07-10 22:18, Roy Smith wrote:=0A>>>  > > Outside this are \=
( and \): these are literal opening =0A> and closing=0A>>>  > > bracket cha=
racters. So:=0A>>>  > > =0A>>>  > >=A0 =A0 \(\([^)]+\)\)=0A>>>  >=0A>>>  > =
although, even better would be to use to utterly awesome=0A>>>  >> re.VERBO=
SE=0A>>>  > flag, and write it as:=0A>>>  > =0A>>>  >=A0 =A0 =A0 \({2} [^)]=
+ \){2}=0A>>> =0A>>>  Or heck, use a multi-line verbose expression and comm=
ent it for=0A>>>  clarity:=0A>>> =0A>>> =A0  r =3D re.compile(r"""=0A>>> =
=A0 =A0  (=A0 =A0 =A0 =A0 =A0 =A0 # begin a capture group=0A>>> =A0 =A0 =A0=
 \({2}=A0 =A0 =A0  # two literal "(" characters [^)]+=A0 =0A> =A0 =A0  # on=
e or more=0A>>> =A0 =A0 =A0 non-close-paren characters \){2}=A0 =A0 =A0  # =
two literal =0A> ")"=0A>>> =A0 =A0 =A0 characters=0A>>> =A0 =A0  )=A0 =A0 =
=A0 =A0 =A0 =A0 # close the capture group """, =0A> re.VERBOSE)=0A>>> =0A>>=
>  -tkc=0A>> =0A>>  Ugh.=A0 That reminds me of the classic commenting anti-=
pattern:=0A> =0A> The sort of dead-simple commenting shown below is not jus=
t harmless but =0A> can be *critically important* for beginners, who otherw=
ise may not know =0A> what "l =3D []" means.=0A> =0A>>  l =3D []=A0 =A0 =A0=
 =A0 =A0 =A0 =A0 =A0 =A0 # create an empty list =0A>>  for i in range(10):=
=A0 =A0  # iterate over the first 10 integers=0A>> =A0 =A0  l.append(i)=A0 =
=A0 =A0 =A0  # append each one to the list=0A> =0A=0AAnything better than t=
his hideous type of commenting: (?#...), e.g=0A>>> re.match("(19|20)[0-9]{2=
}(?#year)-[0-9]{2}(?#month)", "2010-12")=0ASame thing for the 'limsux' modi=
fiers, although *maybe* they can be useful.