[Python-Dev] Deprecating string exceptions

[Barry A. Warsaw]

>>>>> "Fred" == Fred L Drake, Jr <fdrake@acm.org> writes:

    Fred> Except of course that it *will* work in Python version
    Fred> dating back to (I suspect) 1.0; that certainly was being
    Fred> done in 1.2, though I don't think it was ever recommended
    Fred> practice.

    Fred> That it worked before string interning was an accident of
    Fred> implementation: all the 'foo' in your example were in a
    Fred> single code object, and so were ensured by the compiler to
    Fred> be the same object (they shared an entry in the constants
    Fred> table).  After string interning was added, it worked more
    Fred> broadly because interning caused a single 'foo' to be
    Fred> shared.

Of course the first 'foo' and the second 'foo' need not have such a
close lexical relationship.  And can't interning (I think) be
disabled?  (Though I'm sure no one does this.)  Also, isn't interning
limited to just identifier-like strings:

>>> x = 'foo += boy'
>>> y = 'foo += boy'
>>> x is y
0

So, yes the simple example I gave will work, but the more general
concept, that string exceptions cannot guaranteed to be caught by
value, still holds.

-Barry