InitializationValue

represents the settable persistent value with which the symbol sym will be initialized.

represents the settable initialization value for the symbol with the specified complete name.

specifies the persistence locations to search for a possible initialization value.

Details and Options

InitializationValue[sym] is equivalent to InitializationValue[sym,$PersistencePath].
InitializationValue[sym]=value sets an initialization value for sym.
InitializationValue[sym]=value is equivalent to InitializationValue[sym,$PersistenceBase]=value.
The following options can be given:

EvaluationEnvironment	$EvaluationEnvironment	the environment in which the value should be used
MergingFunction	Automatic	the function applied to the list of values found
ValuePreprocessingFunction	Identity	the function applied to new values to be assigned
ExpirationDate	None	when the value should expire
PersistenceTime	None	how long the value should persist

A persistence location is given as PersistenceLocation["type"] or "type".
InitializationValue[sym]=$NoValue specifies that the symbol sym should be unset on initialization.
Before a new value is assigned in InitializationValue[sym]=value, any specified value preprocessing function is applied to value before the value is assigned.
If the preprocessing function returns $Failed, the assignment is not performed.
If no explicit setting for ValuePreprocessingFunction is given, the setting to use is looked up on $PersistencePath.
An expired initialization value is treated as nonexistent, and the underlying persistent object may be removed.
Initialization values can be removed with Remove. Remove[InitializationValue[name]] is equivalent to Remove[InitializationValue[name,$PersistenceBase]].