Modeling.FaultHandler.AccessGenericFaultHandler

Package Modeling :: Module FaultHandler :: Class AccessGenericFaultHandler

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Class AccessGenericFaultHandler

FaultHandler --+
               |
              AccessGenericFaultHandler

Known Subclasses:: AccessArrayFaultHandler, AccessFaultHandler

This is an abstract class providing the following capabilities:

it provides the faults the ability to be chained/grouped together. Note: this is not used in the framework yet, but it will!

It also specifies a generic API based on the fact that this sort of FaultHandlers is based on the "Access Layer", i.e. uses a 'DatabaseContext' and an 'EditingContext' to fetch the datas from an external store/database.

Implementation notes:

!!! DatabaseContext: should be the right one (not the original but the one that is responsible for the object). Maybe this can be checked somewhere TBD

Subclasses must use the '_setContext()' method to initialize the AccessGenericFaultHandler (typically it will be called in '__init__()')

Method Summary
	`completeInitializationOfObject(self, anObject)` Abstract method implemented by subclasses to populate 'anObject'
	`databaseContext(self)` Returns the 'DatabaseContext' object the fault handler uses to fetch data rows from a database.
	`editingContext(self)` Returns the underlying EditingContext --see _setContext().
	`faultWillFire(self, anObject)` Removes itself from the chain of handlers
	`generation(self)` Return the ``generation'' of the fault --see: 'linkAfterHandler()'.
	`linkAfterHandler(self, anAccessGenericFaultHandler, generation)` Adds the FaultHandler to the chain ended by 'anAccessGenericFaultHandler'.
	`next(self)` Returns the successor of 'self' in the chain, or None.
	`previous(self)` Returns the predecessor of 'self' in the chain, or None
	`_handleECDeletion(self, ref)` Automatically called when the EditingContext the FaultHandler (weak-) references is deleted ; simply removes itself from the chain of handlers.
	`_removeSelfFromChain(self)` Removes itself from the chain.
	`_setContext(self, aDatabaseContext, anEditingContext)` Initializes the AccessGenericFaultHandler ; subclasses typically call this method in their '__init__()' method.
Inherited from FaultHandler
	`targetClass(self)`

Class Variable Summary
`NoneType`	`_dbContext` = None
`int`	`_generation` = 0
`NoneType`	`_next` = None
`NoneType`	`_previous` = None
`NoneType`	`_weakref_ec` = None

Method Details

completeInitializationOfObject(self, anObject)

Abstract method implemented by subclasses to populate 'anObject'

Parameter:

anObject -- an object implementing the 'Faulting' interface. Within the

framework, it is typically a 'DatabaseObject'

Overrides:: Modeling.FaultHandler.FaultHandler.completeInitializationOfObject

databaseContext(self)

Returns the 'DatabaseContext' object the fault handler uses to fetch data rows from a database.

editingContext(self)

Returns the underlying EditingContext --see _setContext().

Return value may be None if unset or if the underlying editing context has been garbage-collected (NB: the latter case should not actually happen since an object/fault ``belonging'' to a garbage-collected/deleted EditingContext should normally _not_ be hold elsewhere).

faultWillFire(self, anObject)

Removes itself from the chain of handlers

Subclasses can override this method ; if they do, their implementation must call this implementation.

Overrides:: Modeling.FaultHandler.FaultHandler.faultWillFire

generation(self)

Return the ``generation'' of the fault --see: 'linkAfterHandler()'.

linkAfterHandler(self, anAccessGenericFaultHandler, generation=None)

Adds the FaultHandler to the chain ended by 'anAccessGenericFaultHandler'.

'self' should not have any predecessor, neither 'anAccessGenericFaultHandler' should have any successor in the chain.

NB: Chaining fault handlers is not used in the framework yet.

Parameters:

self -- an AccessGenericFaultHandler for which 'previous()' answers None

anAccessGenericFaultHandler -- an AccessGenericFaultHandler for which 'next()' returns None

generation -- a float indicating when the fault was created. If it is omitted or 'None', it defaults to 'time.time()'

next(self)

Returns the successor of 'self' in the chain, or None.

NB: Chaining fault handlers is not used in the framework yet.

previous(self)

Returns the predecessor of 'self' in the chain, or None

NB: Chaining fault handlers is not used in the framework yet.

_handleECDeletion(self, ref)

Automatically called when the EditingContext the FaultHandler (weak-) references is deleted ; simply removes itself from the chain of handlers.

You should not call this method directly, nor should it be overriden.

_removeSelfFromChain(self)

Removes itself from the chain. You should never call this method, it is automatically called when necessary.

Subclasses should not override this method.

See: faultWillFire()

_setContext(self, aDatabaseContext, anEditingContext)

Initializes the AccessGenericFaultHandler ; subclasses typically call this method in their '__init__()' method.

Parameters:

aDatabaseContext -- the DatabaseContext from which the object's state can be restored. Concrete subclasses use it to restore the object from a database.

anEditingContext -- the editingContext the faulted object is registered to. Note that the EditingContext is weak-referenced, thus a fault handler does not prevent it to be garbage-collected. When this happens, the fault is automatically notified and is invalidated as well --see '_handleDeletion()'.

Class Variable Details

_dbContext

Type:: NoneType
Value:: None

_generation

Type:: int
Value:: 0

_next

Type:: NoneType
Value:: None

_previous

Type:: NoneType
Value:: None

_weakref_ec

Type:: NoneType
Value:: None

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