[NTG-pdftex] \ifprimitive and \ifinternal/\iffeature (design proposal)

Heiko Oberdiek oberdiek at uni-freiburg.de
Mon Jul 4 15:44:51 CEST 2005

On Mon, Jul 04, 2005 at 12:30:47PM +0200, Taco Hoekwater wrote:

> As promised, some proposals for the symbol table. No code yet,
> because careful thinking is needed first, to avoid unexplainable
> side-effects.
> Let me propose two rather straightforward new primitives first
> (please imagine the \ptex prefix yourself):
>   \ifprimitive <csname>
>     True if the <csname> has the same meaning as it would in initex,
>     (but gives an error if <csname> is currently undefined).

What is the result of \ifprimitive, it is \iftrue/\iffalse or
an expansion text "true"/"some error message"?

>   \executeprimitive <csname>

What about \executeprimitive itself?

  \def\executeprimitive{Hello World}

Is the result two "Hello World" or "\relax"?

>     Executes the primitive that would be known as <csname> in initex,
>     even if the <csname> is currently undefined or defined to mean
>     something else. Raises an error if there is no matching internal
>     command (of course).
> These are quite straightforward, and I do not assume this needs
> much discussion.

I need some clarification only.

> But the next ones are related to "if feature ...",
> and those are bit harder to define.
>   \ifinternal <csname>
>   \executeinternal <csname>
>   \exposeinternal <csname>
>   \obscureinternal <csname>


It needs some thinking.
First thoughts:
* It looks like a first step to a real namespace implementation,
  a (perhaps read-only) internal namespace, namespaces for extensions,
  and user/package macros. Why not going further then?
* Perhaps PostScript ideas of dictionary stacks can help here:
  systemdict for internal iniTeX primitives, userdict, ...

Yours sincerely
  Heiko <oberdiek at uni-freiburg.de>

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