The following keywords allow you to call GDL add-ons which provide a deterministic function,
i.e. the result of a given operation depends on the specified parameters only. This process necessarily involves using special Add-On extensions.
For example polygon operations can be executed via the PolyOperations add-on. Add-Ons for other operations can be developed by third parties.
See also the section called “Polygon Operations Extension”.
For background conversion connections, see Background Conversion.
INITADDONSCOPE
INITADDONSCOPE (extension, parameter_string1, parameter_string2)
Opens a channel as directed. Its return value is a positive integer that will identify the specific connection.
This value, the channel number, will be the connection’s reference number in succeeding instances.
extension: string, the name of an existing extension.parameter_string1: string, its contents are interpreted by the extension.parameter_string2: string, its contents are interpreted by the extension.PREPAREFUNCTION
PREPAREFUNCTION channel, function_name, expression1 [, expression2, ...]
Sets some values in the add-on as a preparation step for calling a later function.
function_name: the string or numeric identifier of the function to be called; its contents are interpreted by the extension.expression: parameters to be passed for the preparation step.CALLFUNCTION
CALLFUNCTION (channel, function_name, parameter, variable1 [, variable2, ...])
The function named function_name in the add-on specified by channel is called.
The parameter list must contain at least one value. This function puts the returned values into the parameters as ordered.
The return value is the number of the successfully set values.
channel: channel value, used to identify the connection.function_name: the string or numeric identifier of the function to be called; its contents are interpreted by the extension.parameter: input parameter; its contents are interpreted by the extension.variablei: output parameter.CLOSEADDONSCOPE
CLOSEADDONSCOPE channel
Closes the connection identified by the channel value.