Andreas,

You could also add special unary types to the compiler in a similar way
as the BinaryTypes.  This could allow the postfix ++ message (prefix
would be a little harder).  The increment would happen after the
expression where the ++ message was found.  Then you could write:

C := 1.
Smalltalk lookLike: C++.

This would assing 1 to C, then send #lookLike: with an argument of 1 to
Smalltalk, followed by incrementing the C global by 1 and assigning it
back to the global after sending #lookLike:.

- Stephen


> -----Original Message-----
> From: squeak-dev-admin at lists.squeakfoundation.org 
> [mailto:squeak-dev-admin at lists.squeakfoundation.org] On 
> Behalf Of Andreas Raab
> Sent: Sunday, June 16, 2002 8:23 PM
> To: squeak-dev at lists.squeakfoundation.org
> Subject: [GOODIE] Arithmetic assignments (+= and friends)
> 
> 
> Folks,
> 
> I finally figured out how to get arithmetic assignments (like +=, -=,
> *=) right in Squeak (I always wanted this...) The attached CS 
> changes the compiler so that it will compile all of them 
> correctly. Besides less typing this is in particular useful 
> if you have polymorphic objects which do implement "inplace 
> arithmetic" like float arrays and may want to use it 
> interchangeably with "atomic types". You can now do stuff
> like:
> 
> 	a := 4.
> 	b := 3.
> 	a += b.
> 	a => 7
> 
> as well as:
> 
> 	a := 4 at 0@4.
> 	b := 3 at 3@0.
> 	a += b.
> 	a => a B3DVector3(7.0 3.0 4.0)
> 
> etc. If you're interested in playing with this please note 
> that an expression like:
> 
> 	a += b
> 
> is really compiled into:
> 
> 	a := a perform: #+= with: b.
> 
> e.g., the message #+= is sent before the resulting 
> assignment. This is so that we can both support "atomic 
> types" (like numbers) which implement
> 
> Number>>+= aNumber
> 	^self + aNumber
> 
> as well as more complex implementations which may return self 
> after performing some inplace operation.
> 
> Enjoy,
>   - Andreas
>