LICOS: BoundMethodWeakref Class Reference

'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.

Member Function Documentation

def __call__

(

self

)

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.

Definition at line 113 of file saferef.py.

def __cmp__	(	self,
		other
	)

Compare with another reference

Definition at line 108 of file saferef.py.

def __init__	(	self,
		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.

Definition at line 57 of file saferef.py.

def __new__	(	cls,
		target,
		onDelete = `None`,
		arguments,
		named
	)

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.

Definition at line 35 of file saferef.py.

def __nonzero__

(

self

)

Whether we are still a valid reference

Definition at line 105 of file saferef.py.

def __str__

(

self

)

Give a friendly representation of the object

Definition at line 97 of file saferef.py.

def calculateKey	(	cls,
		target
	)

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.

Definition at line 89 of file saferef.py.

Member Data Documentation

tuple _allInstances = weakref.WeakValueDictionary() [static, private]

Definition at line 34 of file saferef.py.

BoundMethodWeakref Class Reference

Public Member Functions

Public Attributes

Static Public Attributes

Static Private Attributes

Detailed Description

Member Function Documentation

Member Data Documentation


Public Member Functions
def	__new__
def	__init__
def	calculateKey
def	__str__
def	__nonzero__
def	__cmp__
def	__call__
Public Attributes
	deletionMethods
	key
	weakSelf
	weakFunc
Static Public Attributes
tuple	calculateKey = classmethod( calculateKey )
Static Private Attributes
tuple	_allInstances = weakref.WeakValueDictionary()
	__repr__ = __str__