Re: Recursion, Yo

On Fri, 12 Apr 2024 15:03:08 +0200, Janis Papanagnou wrote:

Another one is that you can write (e.g. in Algol 68 or many other higher
level languages) the equivalent of - again a simple example -
 
  int x = 2 * pi * r
 
without necessity to know whether pi is a constant, the result of a
function (calculation), the result of a function implicitly called just
once on demand, or whatever else. Conceptually as a programming language
user you want the value.

In Python you can’t do this with an unqualified name, but you can with a
qualified one, e.g.

    x = 2 * math.pi * r

Which one of these might be true?

* “math” is a module, and “pi” is a variable defined within it
* “math” is a class, and “pi” is a variable defined within it
* “math” is an instance of a class, and “pi” is a variable defined either
within that instance or the class
* “math” is an instance of a class, and “pi” is a “property”, which is
computing a value, on demand, via an implicit method call

Note that the fourth possibility does an implicit method call without
argument parentheses.