[Python-Dev] PEP 292, Simpler String Substitutions

Guido van Rossum guido@python.org
Thu, 20 Jun 2002 00:23:26 -0400

> `...` is already in python though.

But not in this form.

> Better to generalise and/or extend an already existing construct than to
> add a new one, I would assert.

Only if that construct is successful.  `...` has a bad rep -- people
by and large prefer repr().

> Youre also right about `...` being less visible than other pairs of
> delimiters.
> I think, though, that if modifying the % notation, that the requirement
> should be for delimiters that are not parentheses, and ones that
> wouldn't interfere with putting expressions between them. This would
> allow for eval()ing the content between the delimiters.

You could do that with ${...} if it skipped nested {...} inside, which
I plan to implement as an (initially secret) extension.  That should
be good enough.  If you try to put string literals containing { or }
inside ${...} you deserve what you get. :-)

Still, this wouldn't work:

  x = 12
  y = 14
  print "$x times $y equals ${x*y}".sub()

You'd have to pass a special magic dict (which I *won't* supply).

--Guido van Rossum (home page: http://www.python.org/~guido/)