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Module datatypes

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Classes supporting XMLSchema Part 2: Datatypes.

Each simple type definition component instance is paired with at most one basis.simpleTypeDefinition class, which is a subclass of a Python type augmented with facets and other constraining information. This file contains the definitions of these types.

We want the simple datatypes to be efficient Python values, but to also hold specific constraints that don't apply to the Python types. To do this, we subclass each PST. Primitive PSTs inherit from the Python type that represents them, and from a pyxb.binding.basis.simpleTypeDefinition class which adds in the constraint infrastructure. Derived PSTs inherit from the parent PST.

There is an exception to this when the Python type best suited for a derived SimpleTypeDefinition differs from the type associated with its parent STD: for example, xsd:integer has a value range that requires it be represented by a Python long, but xsd:int allows representation by a Python int. In this case, the derived PST class is structured like a primitive type, but the PST associated with the STD superclass is recorded in a class variable _XsdBaseType.

Note the strict terminology: "datatype" refers to a class which is a subclass of a Python type, while "type definition" refers to an instance of either SimpleTypeDefinition or ComplexTypeDefinition.

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