Figure 5.
Dimensional units example.
<![CDATA[
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-- Ada can spot equations that are dimensionally incorrect
-- and add correct conversion factors at compile time.
-- D_U_EX.ada
with STANDARD_INTEGERS, DIM_INT_32;
procedure Dimensional_Units_Example is
type Feet is new DIM_INT_32.Units;
type Meters is new DIM_INT_32.Units;
A, B, C : Feet;
X, Y, Z : Meters;
function Units_Convert(M : Meters) return Feet is
use STANDARD_Integers; -- for multiply
DISTANCE : Integer_32;
begin
-- 1 meter is approximately 3 feet.
DISTANCE := 3 * Dimensionless(M);
return Type_Convert(DISTANCE);
end Units_Convert;
begin
A := B + C;
X := Y + Z;
A := B + Y; -- this line (25) is wrong
A := B + Units_Convert(Y);
end Dimensional_Units_Example;
------------------------------------------
The above code is in a file called D_U_EX.ada. When you
compile it, here's what you get:
C:>ada D_U_EX.ada
Meridian AdaVantage(tm) Compiler
[v2.1 Feb 29, 1988] Target 8086
"D_U_EX.ada", 25: type of function
does not match context "+" [LRM 6.4]
28 lines compiled.
1 error detected.
]]>