[Python-Dev] PEP 292, Simpler String Substitutions

[Guido van Rossum]

> I love this suggestion. It's the sort of thing you can't do in C++ ;-)
> I suspect the arguments against will run to efficiency and complexity,
> since you need to compile the backquoted expressions (in some context).

Actually, I had planned a secret feature that skips matching nested
{...} inside ${...}, so that you could write a magic dict whose keys
were eval()'ed in the caller's context.  The %(...) parser does this
(skipping nested (...)) because someone wanted to do that.

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