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Date: Mon, 2 Apr 2012 08:49:26 -0700 (PDT)
From: Yingjie Lan <lanyjie@yahoo.com>
Subject: Re: string interpolation for python
To: "python-list@python.org" <python-list@python.org>
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> Right, meaning that both have the same issues=A0=0A> of performance, need=
 for=0A=0A> str(), etc. There's absolutely no difference.=0A=0A=0AOK, perfo=
rmance. Here is a new solution:=0A=A0=0ASuppose we have a new string method=
=0A=A0 =A0 str.format_join([...])=0Ataking a list of strings and objects,=
=0Awith even-indexed ones being strings,=0Aodd-indexed ones being objects.=
=0AEach even-indexed string *ends* with a formatting=0Aspecification for th=
e next object in the list.=0AThen we can have:=0A>>>=A0d"sin($x$) =3D $ sin=
(x):0.3f $"=0Aget translated to:=0A>>> ''.format_join(["sin(%s",x,") =3D %0=
.3f", sin(x)])=0AThis seems to be at least as good in performance.=0A=0A=0A=
> And no benefit. You lose out on syntax highlighting=A0=0A> in your editor=
 and=A0gain nothing.=0A=0AGain: readability, terseness, hassle-free, and po=
ssibly=0Abetter performance if done right.=0A=0ASyntax highlighting: can be=
 done more creatively.=0AFor dynamic strings, string parts are like normal=
=A0=0Astrings, but the embedded expressions are like=0Anormal expressions :=
)=0A=0A> =0A> sprintf("UPDATE tablename SET modified=3Dnow()%{,%s=3D:%[0]s%=
} WHERE=0A> key=3D%d",array_of_field_names,primary_key_value)=0A> --> "UPDA=
TE tablename SET modified=3Dnow(),foo=3D:foo,bar=3D:bar,quux=3D:quux=0A> WH=
ERE key=3D1234"=0A> =0A> You're still paying for no complexity you aren't a=
ctually using. =0A> It's=A0clear and readable.=0A=0AYou are really good at =
that. Maybe not everybody is as=0Aexperience as you, and I suppose the lear=
ning curve is=A0=0Akind of hard to climb.=0A=0A> It's powerful only if you =
use eval to allow full expression syntax.=0A> Otherwise, what does it have =
above str.format()?=0A=0A=0AThose expressions are embedded, you don't need =
eval()=0Ato have the result though. Are we on the same page?=0A=0A> You may=
 well be able to get past the compatibility issues. I'm not yet=0A> convinc=
ed that the new syntax is worth it, but it may be possible.=0A> =0A> Here's=
 a recommendation: Write a parser for your notation that turns=0A> it into =
executable Python code (that is, executable in Python 3.3=0A> without any d=
"..." support).=A0=0A=0AYou mean a translator?=0A=0AThe syntax is essential=
 for compatibility.=0AWe must distinguish dynamic strings from common strin=
gs.=0AThey will live peacefully together.=A0=0A(escaping the '$' in normal =
strings breaks compatibility,=A0=0Aand the consequence of forgetting to esc=
ape could be=0Adisastrous, so definitely not an option).=A0=0A=0AMay be d" =
is too tiny, $"..." is easier to pick out.=0A=0A=0A=0ACheers,=0AYingjie=0A