The Wrong Stuff

[Jonathan M Davis]

On Saturday 25 September 2010 22:59:51 Don wrote:
> Jonathan M Davis wrote:
> > On Saturday 25 September 2010 03:23:12 Torarin wrote:
> >> 2010/9/24 Jonathan M Davis <jmdavisProg at gmx.com>:
> >>> However, we're not going to double the number of keywords that we have,
> >>> and the @ syntax has allowed us to remove some keywords and will allow
> >>> us to add more stuff later without having to add keywords.
> >> 
> >> Why are attributes not considered keywords? Because the compiler
> >> doesn't care about them?
> > 
> > Because they don't need to be any more than variable names do. @
> > indicates that what follows is an attribute,  so the next symbol is
> > parsed as an attribute. If it were a keyword, then it wouldn't compile.
> > keywords are always treated as keywords no matter the context. They show
> > up explicitly in the grammar. Attributes do not show up explicitly in
> > the grammar any more than variables do. The grammar indicates when a
> > symbol is a variable, and it's parsed as variables. The grammar also
> > indicates when a symbol is an attribute, and it's parsed as an
> > attribute.
> > 
> > Basically, what it comes down to is that keywords are symbols in the
> > grammar - just like ! or ~ or <. Variable names and attributes are not.
> > 
> > Attributes allow us to add more modifiers to stuff (particularly
> > functions) without having to add new keywords. And someday, we may even
> > be able to define attributes in our own code (right now, they're all
> > known by the compiler) - and that's something that you obviously can't
> > do with keywords.
> > 
> > - Jonathan M Davis
> 
> You can already do that by prefixing with __.

Do you mean that you can use user-defined attributes as long as they're prefixed 
with _ or that you can use keywords if they're prefixed with _? Prefixing a 
keyword with _ makes it so that it's a different token, so it's not going to 
match any keywords. Now, if you mean that you could use your own attributes as 
long as they start with an underscore (.e.g. @_myproperty), then that could be 
useful, but I don't know how you'd be able to make use of it, since you'd need a 
way to get at through __traits or std.traits, and functionAttributes() (which is 
the only function that I see for looking at attributes) isn't string-based but 
rather flag-based, which means that it won't work with anything but a predefined 
set of attributes.

- Jonathan M Davis