Utility Classes :: Exact

Overview

The Exact() utility class is used when you want to assert == equality. In the following signature, the first parameter must be either 6 or 7:

@accepts(IsOneOf(Exact(6), Exact(7)))

Where IsOneOf() is the IsOneOf utility class.

Details

• The Exact() constructor accepts only one argument; to supply more or less than this will raise a TypeError.

• If the object being checked by the Exact instance does not match, a _TC_ExactError will be raised; the wrong attribute will be the invalid object, the right attribute will be the reference object that was being checked against.

  This exception is to be caught and converted to a TypeCheckError before it reaches the level of the user.

• Exact objects will only compare equal (i.e., ==) if their reference objects compare equal with ==.

  All Exact instances that compare equal with == will produce the same value when run through the built-in hash() function.