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The Mapping Class

Before we start, it is worth taking a quick look at the MappingMapping class as a whole and some of the sub-classes it contains:

74#74

The FrameFrame sub-class has been separated out here because it is covered in detail in §7. We start by looking at the parent class, Mapping.

AST does not provide a function to create a basic Mapping (i.e. the astMapping constructor does not exist). This is because the Mapping class itself is “virtual” and basic Mappings are of no use in themselves. The Mapping class serves simply to contain the various specialised Mappings that exist. However, it provides more than just a convenient heading for them because it bestows all classes of Mapping with common properties (e.g. attributes) and behaviour. By examining the Mapping class, we are therefore examining the things that all other Mappings have in common.