Re: Literate Programming [was: A case where ...]

[Eric Merritt <cyberlync@yahoo.com>]

Nick,

 Not to be simplistic but isn't this just a multi-line
comment? I realize that the purpose is to support
literate programming but what you describe seems to be
a multi-line comment line C's /**/. Of course, this
does not mean to imply that the multi-line comments
could not be parsed to extract content by a literate
tool. That being said the syntax you describe could
probably be a bit cleaner so that both those who want
to use literate techniques and those who do not would
be comfortable with it.

--- Nick Roberts <nickroberts@adaos.worldonline.co.uk>
wrote:
> What I think just be might be a worthwhile feature
> to add to a future
> revision would be some kind of line-oriented Ada
> 'on/off switch'.
> 
> This is best explained by an example. Suppose the
> (new) standard defined a
> line in source code, which contained just two
> lexemes, the first === and the
> second an identifier, as being a (say) 'mode
> switch'. If the identifier is
> ADA (ignoring case), the following text lines are
> parsed as Ada source code,
> up to the next mode switch or the end of the file.
> If the identifier is
> anything else, the following text lines are ignored,
> up to the next mode
> switch or the end of the file.
> 
> A file could then contain e.g.
> 
> 
> [begin snippet]
> 
> 
> === docbook
> 
> <para>The next function returns the opposite
> direction
> to the one given as its parameter.</para>
> 
> === ada
> 
>    function Opposite (Way: in Direction) return
> Direction;
> 
> === docbook
> 
> <para>The next function ...
> 
> 
> [end snippet]
> 
> 
> This would mean that normal text files could be used
> to contain mixed
> content, including Ada source code, and yet any
> standard Ada compiler could
> directly compile such files. This would be a huge
> advantage over having to
> pre-process ('tangle') the files before compiling
> them, which tends to
> render the automatic 'make' tools supplied with Ada
> systems useless.
> 
> For the unfamiliar, the essence of 'literate
> programming' (invented by the
> heroic Prof. Don Knuth) is to combine software
> documentation, in its own
> suitable markup language (e.g. TeX or DocBook), with
> the source code itself,
> in the same source file. This simply means you can
> neatly update both source
> code and documentation at the same place, in the
> same file, at the same
> time.
> 
> In the above example, with DocBook combined with
> Ada, the file would be
> pre-processed ('weaved') to produce pure DocBook,
> which would then be
> processed to be rendered on the screen (e.g. in a
> web browser) or formatted
> and printed. This pre-processing could be obviated
> by making the mode
> switches something like "<programlisting
> proglang="Ada"><![CDATA[" and
> "]]></programlisting>".
> 
> It would be advantageous for the switches to be
> defined by the standard, so
> that all Ada compilers would recognize them.
> 
> It would be a splendid opportunity to add a great
> buzzword to Ada: we could
> say it was a "literate programming language". Gotta
> help with advocacy!
> 
> --
> Best,
> Nick Roberts
> 
> 
> 
> _______________________________________________
> comp.lang.ada mailing list
> comp.lang.ada@ada.eu.org
> http://ada.eu.org/mailman/listinfo/comp.lang.ada


__________________________________________________
Do You Yahoo!?
Send FREE video emails in Yahoo! Mail!
http://promo.yahoo.com/videomail/