Appendix A. Creating a language binding for cairo

While cairo is implemented and C, and has a C API, it is expected that many users of cairo will be using it from languages other than C. The glue that connects the core cairo library to another language is known as a language binding. This appendix attempts to collect together issues that come up when creating a language bindings for cairo and present standardized solutions to promote consistency among the different language bindings.

General considerations

The naming of the central cairo_t type is a special exception. The object is “a cairo context” not “a cairo”, and names such as cairo_t rather than cairo_context_t and cairo_set_source() rather than cairo_context_set_source() are simply abbreviations to make the C API more palatable. In languages which have object-oriented syntax, this abbreviation is much less useful. In fact, if ‘Cairo’ is used as a namespace, then in many languages, you'd end up with a ridiculous type name like ‘Cairo.Cairo’. For this reason, and for inter-language consistency all object-oriented languages should name this type as if it were cairo_context_t.

The punctuation and casing of the type names and method names of cairo should be changed to match the general convention of the language. In Java, where type names are written in StudlyCaps and method names in javaCaps, cairo_font_extents_t will become FontExtents and cairo_set_source(cr,source), cr.setSource(source). As compared to changing the punctuation, and casing, much more reluctance should be used in changing the method names themselves. Even if get is usually omitted from getters in your language, you shouldn't bind cairo_get_source() as cr.source().