Patches item #466, was opened at 2006-01-07 17:22 You can respond by visiting: http://sarovar.org/tracker/?func=detail&atid=495&aid=466&group_id=106 Category: Primitives Group: v1.30.0

Status: Closed Resolution: Accepted Priority: 4 Submitted By: Taco Hoekwater (taco) Assigned to: Martin Schröder (oneiros) Summary: \primitive and \ifprimitive

Initial Comment: This patch implements two new primitives: \primitive \par This will run the 'primitive' command \par, even if it has been re- or undefined in the meantime. \primitive is not expandable, because it may be asked to execute unexpandable primitives as well as expandable ones. If you supply a nonexistant primitive, it will be ignored (no error is raised). The second primitive is a new type of \if: \ifprimitive \par ... \else .. \fi returns true if the current meaning of \par is the 'primitive' command \par. The patch is against alpha-20051226, i hope that is not too old (?). I expect to do at least one minor update during the beta cycle, after the pdftex code is flattened. It was quite a struggle to make this change file work ok, and as a result, there are a few ugly web hacks. ---------------------------------------------------------------------- Comment By: Martin Schröder (oneiros) Date: 2006-07-26 12:27 Message: Logged In: YES user_id=421 This has been included in version 1.40 ---------------------------------------------------------------------- Comment By: Bernd Raichle (bernd) Date: 2006-02-14 08:17 Message: Logged In: YES user_id=3344 IMHO it would be better to rephrase the above to (and change the implementation accordingly :-(): <quote mode="changed"> \primitive is expandable, because it may asked to execute expandable primitives as well as unexpandable ones. \primitive<cs> will expand to one token, the original TeX primitive. This token will then be processed further as usual. </quote> If \primitive is left unexpandable, a lot of programming techniques seems to be unavailable, e.g., all redefined expandable primitives in expandable-only context. Or any assignment to the get the original primitive, like \edef\orignumber{\expandafter\noexpand\primitive\number} \expandafter\let\expandafter\orignumber\primitive\number Sidenote: The new \primitive seems to implement a subset of a full-blown namespace mechanism. If (pdf)TeX would have namespaces, one simply has to access the appropriate token within the "primitive" namespace (e.g. \primitive::number to access the original \number primitive, assuming the notation \<namespace>::<csname>). How about choosing an appropriate namespace mechanism for (pdf)TeX and implementing it instead? ---------------------------------------------------------------------- Comment By: Taco Hoekwater (taco) Date: 2006-02-13 18:56 Message: Logged In: YES user_id=1608 We need to think about this. I see your point, but making \primitive expandable forces the introduction of un-redefinable tokens, and that has its own problematic side-effects (like slowing down each and every definition). I welcome third opinions on whether the benefits outweigh that downside. At one point I tried making the expandability depend on the referred primitive, but that gave me headaches at the implementation stage (a pity, because that would have been nice). Yet another solution is to have an expandable command as well as an unexpandable command (two primitives instead of just the single \primitive). On the side note: I will happily write an implementation ... but only if someone comes up with a specification that works under all conditions instead of only under specific programming styles :-) ---------------------------------------------------------------------- Comment By: Bernd Raichle (bernd) Date: 2006-02-13 17:40 Message: Logged In: YES user_id=3344 IMHO it would be better to rephrase the above to (and change the implementation accordingly :-(): <quote mode="changed"> \primitive is expandable, because it may asked to execute expandable primitives as well as unexpandable ones. \primitive<cs> will expand to one token, the original TeX primitive. This token will then be processed further as usual. </quote> If \primitive is left unexpandable, a lot of programming techniques seems to be unavailable, e.g., all redefined expandable primitives in expandable-only context. Or any assignment to the get the original primitive, like \edef\orignumber{\expandafter\noexpand\primitive\number} \expandafter\let\expandafter\orignumber\primitive\number Sidenote: The new \primitive seems to implement a subset of a full-blown namespace mechanism. If (pdf)TeX would have namespaces, one simply has to access the appropriate token within the "primitive" namespace (e.g. \primitive::number to access the original \number primitive, assuming the notation \<namespace>::<csname>). How about choosing an appropriate namespace mechanism for (pdf)TeX and implementing it instead? ---------------------------------------------------------------------- You can respond by visiting: http://sarovar.org/tracker/?func=detail&atid=495&aid=466&group_id=106