Next: , Up: Part II Language Filters   [Contents][Index]


12.1 External Filters

An external filter is a stand-alone program that works on the output of Form Designer and translates the output to the target language. The filter can elect to work on the .fd or the C output or both simultaneously. However, in non-testing situations, the c output from Form Designer probably should be deleted by the filter once the translation is complete.

By default, Form Designer only outputs the .fd and C files. If the presence of -ada, -perl, -python, -fortran, -pascal or -scm command line options to Form Designer is detected, then after emitting the default output, Form Designer invokes the the external filter with the root filename (without the .fd extension) as an argument, together with possible other flags, to the filter. Any runtime error messages are presented to the user in a browser. The filter name by default is fd2xxxx where xxxx is the language name (such as fd2perl etc.), which can be changed using the -filter command line option (or equivalent resources).

The resources that are relevant to the filter are listed below

Resource Type Default
languagestringC
filterstringNone