Re: pascal system

["mdj" <mdj.mdj@gmail.com>]

John B. Matthews wrote:

> The UCSD UNIT model for separate compilation was one of the first to
> enforce a rigorous contract between interface and implementation. In
> particular, it used Pascal's type checking to verify subroutine
> parameters. The original Mac toolbox interfaces were created using this
> model, and we take it for granted now for large APIs.

The really cute part was INTRINSIC UNITS, which you could store in
SYSTEM.LIBRARY, providing true dynamic loading. There was a limit on
the number of UNITS in SYSTEM.LIBRARY though, and even more
restrictions if they contained external (assembly) code, although the
specifics escape me.

There was some non-UCSD extensions in Pascal 1.2 to make this mechanism
a little more user friendly, as I recall.