Front calls

The GGC has a set of implementations for standard front-end calls, such as those to get the front-end name, operating system type, etc., that are handled by default.

Default front calls provide a pre-defined answer. For example, if you use standard.feInfo("feName" ), unless you want it to return "GGC", you will have to overload it and provide the values you expect it to return.

Overloading the defaults means you provide your own implementation of these functions, and you do not use the default implementation the GGC provides. You can implement overloaded functions in Genero BDL or Java.

Specific front call handlers are needed to Implement custom front calls. For sample code, see Example: custom front call (BDL) or Example: custom front call (Java).

The BDL API can also implement front call handlers through the Java API handler interface using option --frontcall-handler frontcall_handler at the command line. See Java front calls with BDL scenario. The front call handler option can be used for both BDL and Java.

If there is a front call in the test, the guilogs and the generated code (comments are generated in the generated code) show which front call is called, but it is not known when it is called. The scenario must therefore register a front call handler as a callback function. Otherwise the tested program may just stop simply because it does not receive the expected information, and an error like 'Not implemented' may be returned.