FORTH and Hypercard

[Geoff Canyon]

On Oct 16, 2005, at 6:47 PM, Stephen Barncard wrote:

> I also liked a feature of Hypercard that was like forth - you could  
> redefine and intercept a lower level handler using the same name. I  
> guess it was a design decision to not allow that in Transcript....  
> but why?
>

I believe it's because of the overhead involved. Calling a user- 
defined routine takes extra time because of the need to track down  
which code should be executed -- the one in the object, the one in  
the group, the one in the card, the one in any of the stacks in use,  
the frontscripts, etc. Calling a native routine has no such overhead.  
If native routines could be overridden, they would all have the  
overhead of user routines, which would slow them down.

Bear in mind I've never touched the engine's source code, and this is  
just a vague memory from a conversation with Scott or Tuviah.

gc