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3.3 Parameters
Parameters are compile-time, constant-valued object members.
They exist only during translation from DML to C; no storage is
allocated for parameters, and they cannot be updated - only overridden.
No type declarations are necessary for parameters; all DML compile-time
computations are dynamically type-checked. The possible types of values
of a parameter are listed below.
Parameters are used to describe static properties of the objects, such
as names, sizes, and offsets. There are a number of standard parameters
that are always defined for every object, and for each object type there
is a set of additional pre-defined parameters. Furthermore, the
programmer can add any number of new parameters, or override the
pre-defined ones.
3.3.1 Parameter Types
A parameter can be assigned a value of one of the following types:
- integer
- An arbitrarily-sized integer value.
- float
- A floating-point value.
- string
- A sequence of characters. String literals are written within double
quotes. Strings can be split over several lines using the +
operator; see Section 4.12.10.
- bool
- One of the values true and
false. These can only be used in tests and boolean
expressions; they are not integer values.
- list
- A list of arbitrary values. Lists are written as [x1, ...,
xN].
- reference
- A reference to a DML object or method.
- undefined
- The value undefined is a unique value which can only be
used in the compile-time test defined x. The result of
the test is false if x has the value
undefined, and true otherwise. The undefined
value is used mainly as a default for parameters that are intended to be
overridden.
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