new DIP5: Properties 2

[Chad J]

Rainer Deyke wrote:
> Kagamin wrote:
>> If dip5 is as bad as opGet_foo is I'll delete it right now.
> 
> What's wrong with opGet_foo?  I like it better than any of the proposed
> new syntaxes for properties:
>   - It keeps the language simple by not adding more syntactic clutter.
>   - In the (very common) case of calculated read-only properties,
> opGet_foo means less typing.
>   - With opGet_foo, the semantics of overriding properties in subclasses
> are obvious.  You can override just the getter, just the setter, or even
> just one setter of many.  You might also be able to do this with a
> dedicated syntax, but it's a lot less obvious.
> 
> 

This seems to me like it adds more syntactic clutter than adding a
keyword would:

PropertyDecl:
	PropertyGetter
	PropertySetter

PropertyGetter:
	Type 'opGet_' Identifier '(' ')'

PropertySetter:
	Type 'opSet_' Identifier '(' Type ')'


Unfortunately, this grammar is wrong.  It needs to be more complicated.
 That's because there is no whitespace between 'opGet_' and Identifier
or between 'opSet_' and Identifier.  This is very unusual since just
about any other pair of tokens in the language is separated by either
optional or mandatory whitespace (AFAIK).

I understand that opGet_XX and opSet_XX are supposed to be parsed as
function declarations or somesuch, but I somehow get the feeling that it
won't fly.  It seems to me like that just makes the semantic analysis do
some of the parsing work.  That's because the semantic analyzer now has
to pull apart the op(G|S)et_ from the Identifier and declare a property
with that identifier as its name.  That step has to be done at some
point and it seems like parsing would be the more appropriate phase for it.