The IFC Exporter PML Object

Template functions called userPreExpProcess.pmlfnc and userPostExpProcess.pmlfnc are supplied. The supplied default templates are called automatically from the graphical user interface postprocess function. If the PML exporter object is used, it is possible to provide the same additional functionality as required but they must be called manually when using the exporter object.

Note:

The templates do not do anything, but it is possible to use them as a framework for your own requirements.

These can be invoked using the commands:

!exporter.userPreProcess()

!exporter.userPostProcess()

Alternatively, you may provide your own functions and inject them into the export process. This is achieved by providing a function or even a series of similar functions, <userFunction>.pmlfnc, for example, IFCPostProcessing.pmlfnc, in the PML search path and then plugging it or them into the system using the command line. These functions take one argument and must handle all PML errors internally. The functions return a string result value containing whatever message is to be transmitted to the running PML application. The template PML functions provide an example of how to structure the function.

These can be defined in the exporter object as below, but there are defaults of:

•

UserPreProcessor = |userPreExpProcess|

•

UserPostProcessor = |userPostExpProcess|

For example:

!exporter = object IFCEXPORTEROBJ( )

!exporter.setUserPreProcessor( |IFCPreProcessing| )

The string values are used to construct a function name, for example, userPreExpProcess.pmlfnc, which the system will attempt to invoke. The export process will not fail if these functions are not found. They are normal PML functions that must be available in the PML search path. A PML REHASH ALL command might be necessary to refresh the PML index files. All error handling must be contained in the files themselves.

When using the PML exporter object directly, there are API functions on the exporter object to set and get these values.

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define method .setUserPreProcessor( !userPreProcessor is STRING )

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define method .getUserPreProcessor( ) is STRING

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define method .setUserPostProcessor( !userPostProcessor is STRING )

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define method .getUserPostProcessor( ) is STRING

For example:

!exporter = object IFCEXPORTEROBJ( )

!exporter.setUserPreProcessor( |IFCPreProcessing| )

!exporter.userPreProcess()

!exporter.export()

!exporter.setUserPostProcessor( |IFCPostProcessing| )

!exporter.userPostProcess()

Please note that a parameter has been added to pre/post processing user function signatures to give user access to the exporter object itself. Note also that the user definable functions must have a signature similar to the ones below, with the single parameter to the exporter object. With the exporter object, all the API functions become available within the pre/post processing functions.

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define function !!userPostExpProcess( !exporter is IFCEXPORTEROBJ ) is STRING

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define function !!userPostExpProcess( !exporter is IFCEXPORTEROBJ ) is STRING

Pre Processing Function

The example finds the elements that need their GUIDs to be set (UUIDIA), instead of just writing out the command message, the actual command syntax can be used to set the attribute.

define function !!IFCPreProcessing( !exporter is IFCEXPORTEROBJ ) is STRING

   -- Start

   !start = !!ce

   -- loop through all elements to export

   !items = !!ifcExportForm.exporter.getExportItems()

   handle any

      !!ce = !start

      return |Failure|

   endhandle

   do !item values !items

      -- collect all items to have their GUIDs set

      var !unsetGUIDs coll all with ( unset( UUIDIA ) ) for $!item

      do !unsetGUID values !unsetGUIDs

         !!ce = !unsetGUID.dbref()

         !name = name

         !message = |Unset GUID on | & !name

         write( !message )

         write( |UUIDENTIFIER SET| )

      enddo

   enddo

   -- Finished

   !!ce = !start

   return |Success|

endfunction

setRefDatumByName

The function call is to use the correct Reference Datum for applying transformations to the imported model. Internally, in the Application Data World, the elements have a special suffix of HDR which is not displayed.

!exporter.setRefDatumByName(|IFCREVIT|)

The command tells the importer to use the Reference Datum / IFCREVIT-HDR as the transformation data.

To use another zone that is outside the Application Data World and not controlled by this user interface, then set the Reference Datum using the DB reference number. For example:

!exporter.setRefDatum(!refZone.DBREF())