From: panu <panu@...>
Date: 2000-11-10T13:10:15+09:00
Subject: [ruby-talk:6240] Dynamic languages need formal typing of public interfaces

Dynamic languages need formal typing of public interfaces

Smalltalk's and other dynamic languages' (Perl, Python, JavaScript,
Lisp, Ruby) strength is that they don't require you to declare the type
of *every* variable used. Instead objects themselves know their type.
This makes programming fun and productive and produces software that is
easy to reuse.

The weakness of dynamic languages is that they don't offer a standard
way for declaring method signatures, which means there is no standard
way of specifying the *contract* a class offers. And even if some of
them offer support for adding type annotations to your code, none (I
know of)   *require* that you use these facilities  where it matters the
most: in the public interfaces.

A  proposal for a standard way to specify public signatures of Smalltalk
classes - adaptable to other dynamic languages - has been made available
at http://members.fcc.net/panu/SRNC-ST.htm.  A new version 1.1. is now
released, the single change being that public methods are allowed to
return literal values (123,  'hello', etc.) without having to explicitly
declare their types.

The SRNC (Signature Revealing Naming Convention) proposal makes the
following argument: We need a compromise between having to declare the
type of *everything*, and not having to declare the type of *anything*.

The rules of SRNC stipulate:  "Formally declare the signatures of your
public methods or else ... they aren't public!".

Panu Viljamaa
<panu@way.com>