Re: The "()" operator revisited.

[Marin David Condic <nobody@noplace.com>]

Just off the top of my head, this would probably break a lot of stuff. 
Currently operators defined with the "" are *infix* operators. The "()" 
is a Idontknowwhatkindoffix operator - and that's likely to cause all 
sorts of parser problems. The "():=" procedure is even more bizarre. Its 
part procedure call and part assignment statement. We've had numerous 
debates here about why you can't make a user defined assignment 
statement as an operator (because assignment is not defined as a 
function) and on top of that, you're creating what looks like assigning 
an expression to a procedure. I'm not sure what the consequences are of 
allowing these to have multiple indicese either - since, again, the 
original restriction on things like ">=" have always been that they were 
infix operators with binary parameters. My guess is this would have to 
make the syntax trees look like an unholy mess.

Its a noble thing to say "Ada ought to support a bunch of containers and 
it ought to do so in as natural a way as possible from the view of the 
programmer". I'm just not sure that this wouldn't break too much stuff 
to be worth it. Perhaps it would be better to invent some container 
concept and invent its own notation in some manner rather than try to 
force them to look like arrays. I'm not sure what that is, but there are 
still lots of special characters left on the keyboard and we could 
always add a few new reserved words (with some pain) - come up with a 
whole new language construct (something based Reverse Polish Notation 
maybe?) or set of constructs for dealing with containers. That might be 
easier to handle than trying to remold array notation.

MDC


Frank J. Lhota wrote:
> Last June, I proposed that in order to provide an abstract array capability,
> Ada 0y should support  user-defined "()" and "():="operators. Since this
> issue has come up again, I would like to summarize and expand on this
> proposal.
> 

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