[Python-Dev] Problems with mro for dual inheritance in C [Was: Problems with the Python Memory Manager]
Travis E. Oliphant
oliphant.travis at ieee.org
Thu Nov 24 18:17:43 CET 2005
Armin Rigo wrote:
> Ok, here is the reason for the leak...
> There is in scipy a type called 'int32_arrtype' which inherits from both
> another scipy type called 'signedinteger_arrtype', and from 'int'.
> Obscure! This is not 100% officially allowed: you are inheriting from
> two C types. You're living dangerously!
> Now in this case it mostly works as expected, because the parent scipy
> type has no field at all, so it's mostly like inheriting from both
> 'object' and 'int' -- which is allowed, or would be if the bases were
> written in the opposite order. But still, something confuses the
> fragile logic of typeobject.c. (I'll leave this bit to scipy people to
> debug :-)
Well, I'm stumped on this. Note the method resolution order for the new
scalar array type (exactly as I would expect). Why doesn't the int32
type inherit its tp_free from the early types first?
a = zeros(10)
[<type 'int32_arrtype'>, <type 'signedinteger_arrtype'>, <type
<type 'numeric_arrtype'>, <type 'generic_arrtype'>, <type 'int'>, <type
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