Metacode mechanics

[Craig Black]

"Kramer" <Kramer_member at pathlink.com> wrote in message 
news:dui66d$20ml$1 at digitaldaemon.com...
> In article <du1q50$1qk8$1 at digitaldaemon.com>, Don Clugston says...
>>
>>David Medlock wrote:
>>> Georg Wrede wrote:
>>>
>>> <snip>
>>>> So I suggest that we:
>>>>
>>>>  - continue developing the current D metalanguage
>>>>  - continue to have both Don's and Phobos' regexps
>>>>  - in this NG start the development of requirements for KBDM
>>>>
>>>> KBDM being Kick-Butt D Metalanguage. :-)
>>>
>>> This is a very good idea, as code-which-generates-code is the heart of
>>> some powerful techniques(Lisp/Scheme macros among them).
>>>
>>> To make them truly work however one of the following is really needed:
>>>
>>> 1. Runtime evaluation, as in scripting type languages.  In this case all
>>> you need is a function which returns a string.
>>>
>>> 2. A _uniform_ way to represent all the constructs of the language. This
>>> works in Lisp because everything is a List(actually a CONS cell), and
>>> you can simply walk the tree checking for symbols and generating code as
>>> needed.
>>
>>I'm sure that compile time reflection is the way to go.
>>We already have the .mangleof property, which maps any type to a string.
>>Once we get array literals, you could have an array of strings showing
>>all members of a given item.
>>eg a property
>>char [][] .membersof
>>which is valid for any type.
>>
>>Then with __identifier(char []) you could walk the syntax tree.
>>
>>Somewhat lacking in syntactic sugar, and doesn't deal with control
>>structures, but it gets you to most of the interesting stuff.
>>
>>I've already written templates that do:
>>char [] qualifiednameof!(alias x)
>>char [] symbolnameof!(alias x)
>>which work for any variable, function, type or module x,
>>and as a side-effect, you get loads of type info. I don't think too many
>>additions would be required to make everything possible. But, you'd
>>certainly want some simplified syntax.
>>
>>> D is much simpler than C++, I will agree wholeheartedly. However, I fear
>>> that such a language strapped on to D would be rife with kludges to
>>> accomodate its (relatively)complex syntax.
>>>
>>> Cheers.
>>> -DavidM
>
> I wonder if Walter checks this news group.  I've heard many people asking 
> for
> some type of full reflection capabilty.  I'm not that great with templates 
> and
> meta-programming, but it sounds like some people here are saying it would 
> help
> fill out D's capabilities in this arena.  Maybe it's time to press for 
> this
> again as a serious improvement to D?... (just thinking out loud)
>
> -Kramer

Don't think it's time to push for reflection yet.  Walter is still 
implementing IFTI, and there are a lot of bugs to fix.

Personally, I think array literals should come before reflection.  To me, 
it's a more fundamental language feature.

-Craig