Get all the instances of one class

[Terry]

Hi,

Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.

br, Terry

 

[Gabriel Genellina]

Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.

Try with gc.get_referrers()

py> import gc
py> class A(object): pass
....
py> a,b,c = A(),A(),A()
py> A
<class __main__.A at 0x00A3F4E0>
py> for item in gc.get_referrers(A): print type(item)
....
<type 'getset_descriptor'>
<type 'getset_descriptor'>
<type 'tuple'>
<class '__main__.A'>
<class '__main__.A'>
<class '__main__.A'>
<type 'dict'>
<type 'dict'>

We need to filter that list, keeping only A's instances:

py> [item for item in gc.get_referrers(A) if isinstance(item,A)]
[<__main__.A object at 0x00A40DC8>, <__main__.A object at 0x00A40DF0>,
<__main__.A object at 0x00A40E18>]

 

[Terry]

Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.

Try with gc.get_referrers()

py> import gc
py> class A(object): pass
...
py> a,b,c = A(),A(),A()
py> A
<class __main__.A at 0x00A3F4E0>
py> for item in gc.get_referrers(A): print type(item)
...
<type 'getset_descriptor'>
<type 'getset_descriptor'>
<type 'tuple'>
<class '__main__.A'>
<class '__main__.A'>
<class '__main__.A'>
<type 'dict'>
<type 'dict'>

We need to filter that list, keeping only A's instances:

py> [item for item in gc.get_referrers(A) if isinstance(item,A)]
[<__main__.A object at 0x00A40DC8>, <__main__.A object at 0x00A40DF0>,
<__main__.A object at 0x00A40E18>]

Thanks! This is what I'm looking for.

 

[Terry]

Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.

Try with gc.get_referrers()

py> import gc
py> class A(object): pass
...
py> a,b,c = A(),A(),A()
py> A
<class __main__.A at 0x00A3F4E0>
py> for item in gc.get_referrers(A): print type(item)
...
<type 'getset_descriptor'>
<type 'getset_descriptor'>
<type 'tuple'>
<class '__main__.A'>
<class '__main__.A'>
<class '__main__.A'>
<type 'dict'>
<type 'dict'>

We need to filter that list, keeping only A's instances:

py> [item for item in gc.get_referrers(A) if isinstance(item,A)]
[<__main__.A object at 0x00A40DC8>, <__main__.A object at 0x00A40DF0>,
<__main__.A object at 0x00A40E18>]

But I saw in the help that we should "Avoid using get_referrers() for
any purpose other than debugging. "

 

[Diez B. Roggisch]

Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.

Try with gc.get_referrers()

py> import gc
py> class A(object): pass
...
py> a,b,c = A(),A(),A()
py> A
<class __main__.A at 0x00A3F4E0>
py> for item in gc.get_referrers(A): print type(item)
...
<type 'getset_descriptor'>
<type 'getset_descriptor'>
<type 'tuple'>
<class '__main__.A'>
<class '__main__.A'>
<class '__main__.A'>
<type 'dict'>
<type 'dict'>

We need to filter that list, keeping only A's instances:

py> [item for item in gc.get_referrers(A) if isinstance(item,A)]
[<__main__.A object at 0x00A40DC8>, <__main__.A object at 0x00A40DF0>,
<__main__.A object at 0x00A40E18>]

But I saw in the help that we should "Avoid using get_referrers() for
any purpose other than debugging. "

Yes, because using it do is very resource-consuming and shouldn't be
done. Why don't you tell us what you are after here & then we might come
up with a better solution?

Diez

 

[Gabriel Genellina]

But I saw in the help that we should "Avoid using get_referrers() for
any purpose other than debugging. "

Yes - so what do you want to do actually?

 

[Tommy Nordgren]

Hi,

Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.

br, Terry

class MyClass : a_base_class
memberlist=[]

# Insert object in memberlist when created;
# note: objects won't be garbage collected until removed from
memberlist.

 

[Terry]

Terry schrieb:

En Fri, 16 May 2008 20:44:00 -0300, Terry <[email protected]>
escribió:
Is there a simple way to get all the instances of one class? I mean
without any additional change to the class.
Try with gc.get_referrers()
py> import gc
py> class A(object): pass
...
py> a,b,c = A(),A(),A()
py> A
<class __main__.A at 0x00A3F4E0>
py> for item in gc.get_referrers(A): print type(item)
...
<type 'getset_descriptor'>
<type 'getset_descriptor'>
<type 'tuple'>
<class '__main__.A'>
<class '__main__.A'>
<class '__main__.A'>
<type 'dict'>
<type 'dict'>
We need to filter that list, keeping only A's instances:
py> [item for item in gc.get_referrers(A) if isinstance(item,A)]
[<__main__.A object at 0x00A40DC8>, <__main__.A object at 0x00A40DF0>,
<__main__.A object at 0x00A40E18>]

But I saw in the help that we should "Avoid using get_referrers() for
any purpose other than debugging. "

Yes, because using it do is very resource-consuming and shouldn't be
done. Why don't you tell us what you are after here & then we might come
up with a better solution?

Diez

I'm developing a message/state_machine based python program (I'm not
using stackless, plan to move to it later).
I want to collect all the state_machines (threads) and send them
'tick' message or 'quit' message.

Now I'm using a static member to collect the machines, just wonderring
if python already provide something like this.

 

[Matt Nordhoff]

class MyClass : a_base_class
memberlist=[]

# Insert object in memberlist when created;
# note: objects won't be garbage collected until removed from memberlist.

Just to say, if you wanted to go about it that way, you could avoid the
garbage collection problem by using weakrefs:

<http://docs.python.org/lib/module-weakref.html>
--