# Converters

For any given widget, each associated resource will have at least two basic representations: the external string representation as entered within X resource files, and the internal format by which the relevent data is manipulated within the widget.

The Motif widget set has a set of built-in converters for changing the X resource string representation into the internal format required.

However, user-defined widgets may support a range of resources of non-standard types for which the existing converters are not appropriate.

In this case, visu needs to know a method of converting the string format as entered within the visu resource panels into the internal representation so that the resource entered can take effect in the dynamic display.

The converter view allows you to specify any functions supplied with your user-defined widgets which convert a text string into the internal resource value.

Fortunately, many widgets configure their own converters internally when the widget class is initialized. If this is the case, all you need to do is add the resource type to the Entries list - this informs visu that the converter exists; otherwise visu will not attempt to set the resource dynamically, although the value will be generated into code or resource files. You will need to inspect your widget documentation to see if the converter is added internally.

If no converter is added internally by the widget, you can ask visu to add them explicitly; simply type in the name of the resource converter in the 'Converter' field provided. Some toggles are provided so you can explicitly state whether visu is also to be configured with the converter (so the dynamic display works), and if the converter specified is to be added to generated code.

Usually, you need to set both toggles if you need to specify a non-standard resource-type converter.

The Popup button allows you to specify a secondary resource panel which will be used for all resources of a given type wherever they occur within the primary resource panels.

Resource converter functions should be of type XtTypeConverter, and you are referred to your X toolkit documentation for more details on this matter.

See also: