BoundMethodWeakref Class Reference

List of all members.

Public Member Functions
	__init__ (target, onDelete=None)
	__str__ ()
	__nonzero__ ()
	__cmp__ (other)
	__call__ ()
Static Public Member Functions
static	__new__ (target, onDelete=None, arguments, named)
static	calculateKey (target)

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Detailed Description

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 calculateKey method applied to the target instance method deletionMethods -- 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 onDelete parameters of safeRef calls. weakSelf -- weak reference to the target object weakFunc -- weak reference to the target function

Class Attributes: _allInstances -- class attribute pointing to all live BoundMethodWeakref objects indexed by the class's calculateKey(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.

Definition at line 53 of file saferef.py.

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Member Function Documentation

__call__ (   )

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.

__cmp__ (  other   )

Compare with another reference

__init__ (  target  , onDelete  = None )

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: target.im_func.__get__( target.im_self ) which is true of built-in instance methods. onDelete -- 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.

static __new__ (  target  , onDelete  = None, arguments  , named  )  [static]

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 deletionMethods attribute updated. Otherwise the new instance is created and registered in the table of already-referenced methods.

__nonzero__ (   )

Whether we are still a valid reference

__str__ (   )

Give a friendly representation of the object

static calculateKey (  target   )  [static]

Calculate the reference key for this reference Currently this is a two-tuple of the id()'s of the target object and the target function respectively.

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The documentation for this class was generated from the following file:

• saferef.py

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