5.5 constant
Use the following grammatical form to declare constant:
Constant_name: class_name is value
such as:
PI: Double IS 3.14159
Base: Integer IS 10
Hello: String is "Hello"
5.6 Object creation process without Make Routine
l Simple categories don't require a specific creative routine, it is also common.
l For example, a category that is only used to provide standard mathematical constants and functions does not require specific initialization.
L Of course, we can always provide an empty Make Routine for the category, which is not required in Eiffel. We can completely ignore the CREATION clause.
Class Basic_Math
- No Creation CLAUSE
FEATURE
PI: Real IS 3.14159
Euler: Real is 2.71828
SIN (X: REAL): Real IS
....
end
Users of this category may create a Basic_Math entity by declaring a variable, such as
BM: Basic_Math
Then execute the command
!! BM
This command allows the system to assign space for a Basic_Math type object and returns a pointer to the object to a variable BM.
In this case, you don't need to perform Make at all.
5.7 Self-reference
l Each object-oriented language provides an object to reference its own way.
l In Eiffel, use current to refer to the current object. The most frequent usage of Current is to provide another object to a reference to the previous object.
Class Some_window_class
Sub: another_window_class
...
!! Sub.make (current)
...
end
Class Another_Window_class
Parent: some_window_class
...
Make (p: some_window_class) IS
DO
Parent: = P
end
(Full text)
[Translation Reference]:
[OOSC2E] Bertrand Meyer, Object-Oriented Software Construction 2nd Edtion. 1997
