Re: Declaring super types

On Apr 19, 8:23 pm, Nilone <rea..._at_gmail.com> wrote:

> How would you want to use that relationship? Any examples to study?

For example, functions that accept RATIONAL values could be passed values of type INTEGER.

It’s quite useful. E.g. even in a low level language like C there are handy conversions amongst the built-in types:

  double sqrt(double);

  double x = sqrt(4); // integer 4 has implicit conversion to double

BTW C++ allows one to write user-defined value types supporting implicit conversion from builtin-types, by writing single argument constructors. Actually I just posted to comp.lang.c++.moderated asking whether it can be regarded as a general purpose approach to value subtyping in that language. But it does seem strange for a type to declare itself as a supertype of another type. Received on Mon Apr 19 2010 - 15:16:39 CEST