[Python-Dev] Interning string subtype instances

["Martin v. Löwis"]

Mike Klaas schrieb:
>> cause problems for other users of the interned string.  I agree with the
>> reasoning, but propose a different solution: when interning an instance
>> of a string subtype, PyString_InternInPlace could simply intern a copy.
> 
> Interning currently requires an external reference to prevent garbage
> collection (I believe).  What will hold a reference to the string
> copy?

For PyString_InternInPlace, the caller will receive a reference; the
original object passed in is decref'ed.

A typical caller of PyString_InternInPlace will just store the reference
in some global/static variable. builtin_intern will return it to the
caller, which then needs to store it. This was always the case with
intern();  the usage pattern is

    foo = intern(foo)

as intern may return a different object (e.g. if the string was already
interned).

Regards,
Martin