The PreExecute method is called first when ENVITask::Execute runs. It performs the following actions:

• Resets all output parameters to !NULL.
• Updates input parameter values from keywords set on ENVITask::Execute.
• Generates temporary files and folders for input ENVIURI and ENVIVirtualizableURI parameters, if not set by the end user.
• Verifies that input URI parameters that generate output have write permissions and do not already exist.
• Validates that all required input parameters are set.

Syntax

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In most cases, the PreExecute method is called by ENVITask::Execute. The only time it should be called explicitly is when a base class other than ENVITaskFromProcedure overrides ENVITask::Execute. When called explicitly, the syntax is as follows:

Obj -> [ENVITaskFromProcedure::]PreExecute, _REF_EXTRA=refExtra

Routine Signature

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To overload an object class in order to add more functionality to PreExecute, implement a method with the following signature:

PRO class::PreExecute, _REF_EXTRA=refExtra

Version History

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ENVI 5.2. 1

Introduced

API Version

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4.2

See Also

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ENVITask, ENVITaskFromProcedure, Custom Tasks