itcl : Is it recommended to have separate spec and body source files ?

Here are 4 itcl scripts that enlight the question "is it recommended to have separate spec and body source files ?" :

The idea behind this is to have a stable spec file and some many moving body implementations.

The specification of class :

 class MySimpleObject {
         public variable name

         constructor { {aName "unknown"}  } {
                 set name $aName
                 return $this
         }

         method name {}

 }

A first version of the body :

 body MySimpleObject::name {} {
         return $name
 }

A second version of the body :

 body MySimpleObject::name {} {
         return "My name is $name"
 }

The main one which shows a change in implementation of the same spec :

 package require Itcl;

 namespace eval itcl {
         source "MySimpleObject-spec.itcl"
         source "MySimpleObject-body-1.0.itcl"

         MySimpleObject my 

         puts [my name]
         my configure -name "Laurent"
         puts [my name]
         source "MySimpleObject-body-1.1.itcl"

         puts [my name]
 }

This is the output :

 $ tclsh85 MySimpleObject.itcl
 Tcl
 Laurent
 My name is Laurent