remove ._state property on instances and use a plain ._sa_attr_state dict

[Former user]

it should be named something non-collisionworthy such as the current _sa_attr_state.

the only gain from the property is that it is readonly, i.e. obj._state = None is not allowed (as well as del'ete). But i can do obj._sa_attr_state = None (and all goes to hell). If that property disappears alltogether, we are left with a plain _sa_attr_state attribute, which can be now set to None and deleted... which is more or less same as before less the complications with the property. Fair trade, no?

Second, i went to r3312, let init_attr() set a _state as plain dict and removed _state as property. The difference plain-dict/property (in favor of plain dict) is like 2-3%.

property: loaded 10 items each with 500 subitems 523034 function calls (512957 primitive calls) in 2.556 CPU s loaded 30 items each with 500 subitems 1564374 function calls (1534297 primitive calls) in 7.796 CPU s loaded 16 items each with 1500 subitems 2499436 function calls (2451359 primitive calls) in 12.518 CPU s

plain dict: loaded 10 items each with 500 subitems 513014 function calls (502937 primitive calls) in 2.525 CPU s loaded 30 items each with 500 subitems 1534314 function calls (1504237 primitive calls) in 7.623 CPU s loaded 16 items each with 1500 subitems 2451404 function calls (2403327 primitive calls) in 12.196 CPU s

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no init_attr() here, the dict is setup in mapper._create_instance(). if u feel this is wrong, get back the init_attr call from 3312

[Mike Bayer]

made some more dramatic changes including this in 9717c7170917856e07331796d8439d30ac93006e.