Maximum of 2 INTEGERS?

Question

What's the syntax for the maximum of 2 INTEGERS?

Eiffel documentation is so bad, literally could not find the answer to this simple question anywhere!

Or does it not exist and I have to use if-statements?

Answer 1

In most cases in Eiffel, the source is all the documentation you need. By right-clicking on a class' name in EiffelStudio, you can see its ancestor tree. You can also use the flat view feature to see all the inherited features of a class within the same editor.

Typically, INTEGER is an alias for INTEGER_32. INTEGER_32 inherits from COMPARABLE (through INTEGER_32_REF). COMPARABLE provides the max and min features. Their signature is

max (other: like Current): like Current

meaning all descendants of COMPARABLE take and return another value of the same type as themselves.

Therefore:

local
  a, b, maximum: INTEGER
do
  a := <some value>
  b := <some value>
  maximum := a.max(b) -- or b.max(a)
end

Eiffel has a unified type system, which means every type is defined as a class, even 'primitive' types that get special treatments in most other languages. INTEGER, CHARACTER, BOOLEAN, ARRAY and other such basic types thus come with a rich set of features you can consult in their own class files like you would with any other type. Since operators are defined as regular features too, this is also the way to figure out exactly what operators exist for any given class.