Figure 11.
NUMERIC_UNITS example.
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-- Sometimes trying to make a generic unit too universal is
-- more trouble than it is worth. Here's what happens if you
-- try to combine the integer and floating dimensional
-- packages. (This is just the beginning of trouble.)
with STANDARD_INTEGERS;
generic
type Numeric_type is private;
with function "-"(RIGHT : Numeric_type)
return Numeric_type is <>;
with function "+"(LEFT, RIGHT : Numeric_type)
return Numeric_type is <>;
with function "-"(LEFT, RIGHT : Numeric_type)
return Numeric_type is <>;
with function "*"(LEFT, RIGHT : Numeric_type)
return Numeric_type is <>;
with function "/"(LEFT, RIGHT : Numeric_type)
return Numeric_type is <>;
with function "/"(LEFT, RIGHT : Numeric_type)
return STANDARD_INTEGERS.Integer_32;
with function "/"(LEFT, RIGHT : Numeric_type)
return float;
with function "abs"(RIGHT : Numeric_type)
return Numeric_type is <>;
with function "rem"(LEFT, RIGHT : Numeric_type)
return Numeric_type is <>;
with function "mod"(LEFT, RIGHT : Numeric_type)
return Numeric_type is <>;
with function ">"(LEFT, RIGHT : Numeric_type)
return boolean is <>;
with function ">="(LEFT, RIGHT : Numeric_type)
return boolean is <>;
with function "<"(LEFT, RIGHT : Numeric_type)
return boolean is <>;
with function "<="(LEFT, RIGHT : Numeric_type)
return boolean is <>;
package NUMERIC_UNITS is
type Units is new Numeric_type;
-- These functions convert pure numbers into
-- dimensioned quantities, and vice versa.
function Type_Convert(X : Numeric_type) return Units;
function "+"(X : Numeric_type) return Units;
function "-"(X : Numeric_type) return Units;
-- These are all the arithmetic functions you need.
function "+"(RIGHT : Units)
return Units;
function "-"(RIGHT : Units)
return Units;
-- and so on
end NUMERIC_UNITS;
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