bukzor a écrit :
On Sep 3, 1:02 pm, Bruno Desthuilliers
<[EMAIL PROTECTED]> wrote:
bukzor a écrit :
(snip)
Thanks for the reply. Just to see it not work, I tried to remove
__getattribute__ from LateInitMixIn, but couldn't get it to work.
??? Sorry, I don't get what you mean...
Since you said __getattribute__ is an attribute of the class, I tried
to run (something to the effect of) delattr(self.__class__,
"__getattribute__"),
Ah, ok. Definitively *not* a thing to do...
but it threw an AttributeError.
You'd have to call it on the mixin class itself, not on a subclass.
My Base class is a C class (_mysql.connection from MySQLdb) that
sometimes segfaults if you try to use it before it's fully
initialized,
... I have used MySQLdb for years on more than a dozen linux
distribs, and never had such a problem. Is this a known bug ? Or is
there something wrong with your setup ?
I'm trying to optimize my number of connections
Connection pooling anyone ? IIRC, this is something that already exists
in quite a couple libs / frameworks. Is there a reason you try to roll
your own ?
by not fully
initializing (read: not connecting) my connection until it's used in
some way. Of course the maintainer didn't envision this (mis)use, so
the object sometimes throws bad errors until it's fully initialized.
Ok.
Of course the *correct* way to do this is to be more careful about
when I create connections, but I think I should be able to get this to
work, and it (would be) much easier to do it The Right Way once it
works.
Please pardon me for repeating the same thing over and over, but messing
with __getattribute__ is certainly not the way to go.
so unfortunately I think I need to use __getattribute__
to do this. I'm doing all this just to make the connection not
actually connect until used.
I may be dumb, but I don't get how this is supposed to solve your
problem. But anyway : there's a known design pattern for what you're
trying to do, that doesn't require mixins nor messing with
__getattribute__ (which, I repeat, is more often than not something you
*don't* want to do). The name of the design pattern is "proxy". I
strongly suggest that you 1/ try to cure the real problem instead of
hacking around and 2/ read about the proxy design pattern.
My 2 cents...
I like the idea of mix-ins, but can't figure out how to make a proxy
work that way.
You mean, "how to use a proxy for lazy initialization" ? Heck, that's
the exact use case in the GoF.
For a long time I had a proxy class that added five or
six features on top of the MySQLdb package, but it wasn't configurable
enough, and I'm working on splitting each feature into its own MixIn
class.
As an aside, this is working for me pretty well. The "reconnect"
method (inheritied from a "Reconnectable" mixin) uses several of the
object's attributes, so I need to set _inited beforehand so that I
don't get into an infinite __getattribute__ loop. What I'd *really*
like to do is remove __getattribute__ from the object at that point.
You can't. Or, more exactly, all you can do is remove __getattribute__
from the mixin class - but then the mixin class won't work anymore. I
don't mean to be condescendant, but it looks like you don't have a clear
understanding of Python's object model here - else you wouldn't even
consider doing such a thing. FWIW, I posted a solution based on the
__getattr__ hook, which did work - at least for the "specs" implied by
your code snippet.
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