[texhax] FW: Re: Implementing control sequences with key values

[Uwe Lueck]

"Philip Taylor (Webmaster, Ret'd)" 
wrote on 23.11.2010 
-- or "will write"!? (I am also told that the e-mail address is invalid) --
at 12:51:35:
>Paul Isambert wrote:
>
>> Both solutions I have adopted in some places, instead of braces. You've
>> asked earlier why using the "=" syntax, and Phil mentioned plain TeX.
>> I'll elaborate and say: you can make do without braces in many cases,
>> something LaTeX seems to want its users to forget. I for one hate them,
>> for no good reason but anyway, and I always welcome alternatives
>> (starting with TeX's syntax for assignments).
>
>Agreed : exactly how I feel.

I seem to share some feelings without being able to determine the exact amount:

"=" may make the code more intuitive, helps to see that it is an assignment 
as opposed to, say, a formatting instruction for a text argument. 

I have guessed that the rationale of LaTeX's restricted syntax is 
that absolute beginners should not be confused with too many 
kinds of syntax. Some people have been told 
"write a thesis on ... with LaTeX and give to me in six months from now!" ... 
With the "Short Introduction to LaTeX", I really was able to produce 
fine text after a few days. 

"Paul Isambert" <zappathustra at free.fr> wrote 14.11.2010 17:28:25:
> Anyway, Vafa, are you trying to mimick TeX assignments or key-value's? In the
> former case (which is investigated here), nothing will be perfect. In the
> latter, though, the "key = value" pair is normally well delimited (e.g. by a
> comma or the end of the list), so the value can be easily retrieved.

So I realize another difference: the usual key-value syntax would be 

    direction=RTL

-- without the leading backslash. This observation makes me suggest a single macro \macroassignment:

    \macroassignment{direction=RTL}

that eventually executes \def\direction{RTL}.

You can make an even smarter \assignment that finds out whether \direction is macro or a register. 

I think you can adopt something from existing packages for this, e.g., fontspec seems to use optional macro arguments with key-value syntax.

Cheers, 

    Uwe.