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rM t | � r< t j | | � St j | � SYn& X| d k rs t d | d | � } | Sd S)a� Return a *safe* weak reference to a callable target.
- ``target``: The object to be weakly referenced, if it's a bound
method reference, will create a BoundMethodWeakref, otherwise
creates a simple weakref.
- ``on_delete``: If provided, will have a hard reference stored to
the callable to be called after the safe reference goes out of
scope with the reference object, (either a weakref or a
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d � Z d d � Z � S)r a� 'Safe' and reusable weak references to instance methods.
BoundMethodWeakref objects provide a mechanism for referencing a
bound method without requiring that the method object itself
(which is normally a transient object) is kept alive. Instead,
the BoundMethodWeakref object keeps weak references to both the
object and the function which together define the instance method.
Attributes:
- ``key``: The identity key for the reference, calculated by the
class's calculate_key method applied to the target instance method.
- ``deletion_methods``: Sequence of callable objects taking single
argument, a reference to this object which will be called when
*either* the target object or target function is garbage
collected (i.e. when this object becomes invalid). These are
specified as the on_delete parameters of safe_ref calls.
- ``weak_self``: Weak reference to the target object.
- ``weak_func``: Weak reference to the target function.
Class Attributes:
- ``_all_instances``: Class attribute pointing to all live
BoundMethodWeakref objects indexed by the class's
calculate_key(target) method applied to the target objects.
This weak value dictionary is used to short-circuit creation so
that multiple references to the same (object, function) pair
produce the same BoundMethodWeakref instance.
Nc s� | j | � } | j j | � } | d k rA | j j | � | St t | � j | � } | | j | <| j | | | | � | Sd S)a� Create new instance or return current instance.
Basically this method of construction allows us to
short-circuit creation of references to already- referenced
instance methods. The key corresponding to the target is
calculated, and if there is already an existing reference,
that is returned, with its deletion_methods attribute updated.
Otherwise the new instance is created and registered in the
table of already-referenced methods.
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t | j � | _ d S)a� Return a weak-reference-like instance for a bound method.
- ``target``: The instance-method target for the weak reference,
must have im_self and im_func attributes and be
reconstructable via the following, which is true of built-in
instance methods::
target.im_func.__get__( target.im_self )
- ``on_delete``: Optional callback which will be called when
this weak reference ceases to be valid (i.e. either the
object or the function is garbage collected). Should take a
single argument, which will be passed a pointer to this
object.
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r r r r � s zBoundMethodWeakref.__init__c C s" t t | � � t t | � � f S)z�Calculate the reference key for this reference.
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r r r r � s z BoundMethodWeakref.calculate_keyc C s d | j j | j | j f S)z-Give a friendly representation of the object.z %s(%s.%s))r! r3 r2 r4 )r* r r r �__str__� s zBoundMethodWeakref.__str__c C s
| � d k S)z'Whether we are still a valid reference.Nr )r* r r r � __nonzero__� s z BoundMethodWeakref.__nonzero__c C s; t | | j � s( t | j t | � � St | j | j � S)z Compare with another reference.)�
isinstancer! Zcmp�typer )r* �otherr r r �__cmp__� s zBoundMethodWeakref.__cmp__c C sA | j � } | d k r= | j � } | d k r= | j | � Sd S)a? Return a strong reference to the bound method.
If the target cannot be retrieved, then will return None,
otherwise returns a bound instance method for our object and
function.
Note: You may call this method any number of times, as it does
not invalidate the reference.
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