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Þ=®d# ã @ sT d Z ddlZddlZddlZddlZe d¡Ze d¡Zd ddZG dd dZ dS )
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z-Refactored 'safe reference from dispatcher.pyé NÚ__self__Ú__func__c C s z t | }W n: tk
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rF t|r4t | |¡ Y S t | ¡ Y S Y n>X |dk rt| dstt| dsttd| dt| |d}|S dS )aÖ 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
|
BoundMethodWeakref) as argument.
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NÚim_funcr zsafe_ref target z@ has im_self, but no im_func, don't know how to create reference)ÚtargetÚ on_delete)Úget_selfÚAttributeErrorÚcallableÚweakrefÚrefÚhasattrÚAssertionErrorÚBoundMethodWeakref)r r Úim_selfÚ reference© r úGd:\z\workplace\vscode\pyvenv\venv\Lib\site-packages\blinker/_saferef.pyÚsafe_ref. s
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ÿ r c sl e Zd ZdZe ¡ Zd fdd ZdddZe dd Z
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d d
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Z e Z d d Z d d Zdd Zdd Z ZS )r a 'Safe' and reusable weak references to instance methods.
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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 |¡}|dk r.|j |¡ |S t | ¡}|| j|< |j||f|| |S dS )aô Create new instance or return current instance.
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|
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
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table of already-referenced methods.
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N)Ú calculate_keyÚ_all_instancesÚgetÚdeletion_methodsÚappendÚsuperÚ__new__Ú__init__)Úclsr r Ú argumentsÚnamedÚkeyÚcurrentÚbase©Ú __class__r r r q s
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zBoundMethodWeakref.__new__c C sf | fdd}|g| _ | |¡| _t|}t|}t ||¡| _t ||¡| _t || _
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t |j | _ dS )a Return a weak-reference-like instance for a bound method.
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|
- ``target``: The instance-method target for the weak reference,
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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
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object.
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c S sÀ |j dd
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¡ d }t d| d| d| Y nX Y qDX qDdS )z=Set self.isDead to True when method or instance is destroyed.Né zException during saferef z cleanup function z: ) r r# r r ÚKeyErrorr Ú ExceptionÚ tracebackÚ print_excr ÚsysÚexc_infoÚprint)ZweakÚselfÚmethodsÚfunctionÚer r r Úremove s$ ÿz+BoundMethodWeakref.__init__.<locals>.removeN) r r r r Úget_funcr
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r Ú weak_selfÚ weak_funcÚstrÚ self_nameÚ__name__Ú func_name)r, r r r0 r r r r r r s
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zBoundMethodWeakref.__init__c C s t t|t t|fS )z°Calculate the reference key for this reference.
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Currently this is a two-tuple of the id()'s of the target
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object and the target function respectively.
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)Úidr r1 )r r r r r r · s z BoundMethodWeakref.calculate_keyc C s d | jj| j| j¡S )z-Give a friendly representation of the object.z {}({}.{}))Úformatr# r6 r5 r7 ©r, r r r Ú__str__À s
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ýzBoundMethodWeakref.__str__c C s t | j| jfS )N)Úhashr5 r r: r r r Ú__hash__Ê s zBoundMethodWeakref.__hash__c C s
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| dk S )z'Whether we are still a valid reference.Nr r: r r r Ú __nonzero__Í s z BoundMethodWeakref.__nonzero__c C s. t || js t | jt|¡S t | j|j¡S )z Compare with another reference.)Ú
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isinstancer# ÚoperatorÚeqÚtyper )r, Úotherr r r Ú__eq__Ñ s zBoundMethodWeakref.__eq__c C s. | ¡ }|dk r*| ¡ }|dk r*| |¡S dS )a? Return a strong reference to the bound method.
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If the target cannot be retrieved, then will return None,
|
otherwise returns a bound instance method for our object and
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function.
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Note: You may call this method any number of times, as it does
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not invalidate the reference.
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N)r2 r3 Ú__get__)r, r r. r r r Ú__call__× s
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__module__Ú __qualname__Ú__doc__r
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