GWT clone

Ellery Newcomer ellery-newcomer at
Sat May 22 12:15:38 PDT 2010

On 05/22/2010 01:19 PM, Mathias Laurenz Baumann wrote:
> Greetings,
> I want to write a web-library/framework, similar to [1]Webtoolkit or
> [2]GWT.
> For that I need to transform a sub portion of D code to javascript.
> Additionally, I dislike changing the toolchain, which means it has all
> to happen at the
> compilation time.
> I want to know what you think about the following possibilities and
> whether you know better ones.
> a)
> Write a compile-time template based parser for D to JS code and parse
> the .d files and transform them
> b)
> write a initialization-time parser for D to JS code, to access the D
> code, each to-be-converted file
> needs to have its own code as string, like char[] src = __FILE__;

Sounds like an absolutely enormous job. Assuming you had a working d 
parser and semantic analyzer (and in-depth understanding of its inner 
workings), it could probably be done in less than six months (as long as 
the language it was written in doesn't *cough* suck).

Currently, I believe there is only one semantic analyzer for D on the 
planet: the dmd front end. Use it as is, use Ary's port, use Denis' 
port. (a) is not an option in this case, unless you want to spend most 
of forever porting the dmd front end to compile time evaluatable D.

And you will have to support the entire D language if by toolchain you 
mean you want access to the routines in phobos or tango or whatever. (If 
not, then I don't see the point of converting your D code to JS 
mechanically.) And then you're going to have to deal with things like 
extern(C), which are all over the place in both libraries, which I 
suspect is nontrivial or not possible.

So unless I've misunderstood something, I don't think avoiding JS is 
really worth all the effort. Sorry for being a pessimist.

Question: as someone who has never used either of the engines that you 
reference, do they actually perform impl language -> JS conversions?

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