This post originated from an RSS feed registered with Agile Buzz by James Robertson. Original Post: Typing Terminology Feed Title: Cincom Smalltalk Blog - Smalltalk with Rants Feed URL: http://www.cincomsmalltalk.com/rssBlog/rssBlogView.xml Feed Description: James Robertson comments on Cincom Smalltalk, the Smalltalk development community, and IT trends and issues in general. Latest Agile Buzz Posts Latest Agile Buzz Posts by James Robertson Latest Posts From Cincom Smalltalk Blog - Smalltalk with Rants

Typing terminology is one of the areas where developers end up talking right past each other - because we use the same terms to mean different things. Take the following descriptions of typing:

• Static
• Dynamic
• Manifest
• Weak
• Strong

Now, go look in the archives of cls, or comp.object - likely other groups as well, but I'm less familiar with them. Try to get common usage for any of those terms. Take one that is bandied about between Java and Smalltalk advocates, for instance - "static". We typically use it to discuss whether variable types are declared manually by the developer in the source code. That seems simple enough... until you get a functional language developer in the mix. They'll talk about their language(s) as being statically typed - even though there are no manual declarations (or at least, no requirement for them). What they mean is that the types are not declared by the developer, but the compiler infers them and enforces them at compile time

This led me to start using the term "manifest typing" to mean manual declarations. That was fine, until I ran across this on Planet Lisp. Patrick Logan pointed out to me that Lispers mean this:

What this means is the object is inseparable from the type at runtime. The object always comes with a "manifest" that describes the type of object.

Whether that manifest is manually defined or dynamically inferred is apparently a separate issue. And heck, that doesn't even get into the more common confusions over Strong/Weak - many people equate manually declared type declarations with Strong typing (forgetting the way you can cast yourself into oblivion in C) - and also equate a lack of manual declarations with weak (forgetting that Smalltalk, for instance, gives you well defined behavior for a message that is not unnderstood).

The bottom line? You have to be extremely careful when you discuss this topic and start tossing jargon around - otherwise, you could end up making as much sense as a guy from Germany discussing Football with an American, each completely sure that they know full well what football means!