Bad interaction between new interpretation of underscore and modules
Hi all, today's beta introduced a really strange problem. Consider two source files: definitions.tex: \startmodule[definitions] \def\lambdax{\lambda_x} \stopmodule[definitions] main.tex: \usemodule[definitions] \starttext blah $\lambdax$ blah. \stoptext This results in the following compile error: ! Undefined control sequence. \lambdax ->\lambda_x l.5 blah $\lambdax $ blah. ? However, if you change "\usemodule[definitions]" into "\input definitions" instead, then there is no compile error! My understanding is that the underscore is a valid character for macro names now outside of math mode, which is what is causing the problem. But I really don't understand what magic is going on in the modules code to trigger this. I would be very interested in an explanation of what is going on. Many thanks, Mathieu
Am 13.01.2011 um 17:18 schrieb Mathieu Boespflug:
Hi all,
today's beta introduced a really strange problem. Consider two source files:
definitions.tex: \startmodule[definitions] \def\lambdax{\lambda_x} \stopmodule[definitions]
main.tex: \usemodule[definitions] \starttext blah $\lambdax$ blah. \stoptext
This results in the following compile error:
! Undefined control sequence. \lambdax ->\lambda_x
l.5 blah $\lambdax $ blah. ?
However, if you change "\usemodule[definitions]" into "\input definitions" instead, then there is no compile error! My understanding is that the underscore is a valid character for macro names now outside of math mode, which is what is causing the problem. But I really don't understand what magic is going on in the modules code to trigger this.
I would be very interested in an explanation of what is going on.
You need \normalsubscript in your module. You define a command and in this case it doesn’t matter that you plan to use it in math mode, the _ is now a normal letter like “a” and this won’t change when you call \lambdax in your document. Write \def\lambdax{\lambda\normalsubscript x} and it will work again. Wolfgang
On Thu, 13 Jan 2011, Wolfgang Schuster wrote:
Am 13.01.2011 um 17:18 schrieb Mathieu Boespflug:
Hi all,
today's beta introduced a really strange problem. Consider two source files:
definitions.tex: \startmodule[definitions] \def\lambdax{\lambda_x} \stopmodule[definitions]
main.tex: \usemodule[definitions] \starttext blah $\lambdax$ blah. \stoptext
This results in the following compile error:
! Undefined control sequence. \lambdax ->\lambda_x
l.5 blah $\lambdax $ blah. ?
However, if you change "\usemodule[definitions]" into "\input definitions" instead, then there is no compile error! My understanding is that the underscore is a valid character for macro names now outside of math mode, which is what is causing the problem. But I really don't understand what magic is going on in the modules code to trigger this.
I would be very interested in an explanation of what is going on.
You need \normalsubscript in your module. You define a command and in this case it doesn’t matter that you plan to use it in math mode, the _ is now a normal letter like “a” and this won’t change when you call \lambdax in your document.
Write
\def\lambdax{\lambda\normalsubscript x}
and it will work again.
Untested: \def\lambdax{\math{\lambda_x}} should also work. Aditya
Am 13.01.2011 um 23:43 schrieb Aditya Mahajan:
Untested:
\def\lambdax{\math{\lambda_x}}
should also work.
Not, this won’t work in a module because _ has catcode 11 when you define the \lambdax command and it doesn’t matter whether you use \math, $ or \Ustartmath. What happens is that TeX tries to expand the not existent command “\lambda_x”. Wolfgang
Thank you for the solution, Wolfgang. But it seems rather painful to
have to replace every occurrence of _ in my definitions module with
the very verbose \normalsubscript just because it's a module. The new
default catcode for _ introduces extra difficulty when defining math
macros. Would it be possible to at least have a macro to revert to the
old behaviour? Also, I'm still stumped as to why modules make any
difference here. I would have expected this problem to also show up if
the definitions were made inline at the top of the source file for the
document.
All the best,
Mathieu
On Thu, Jan 13, 2011 at 10:50 PM, Wolfgang Schuster
Am 13.01.2011 um 17:18 schrieb Mathieu Boespflug:
Hi all,
today's beta introduced a really strange problem. Consider two source files:
definitions.tex: \startmodule[definitions] \def\lambdax{\lambda_x} \stopmodule[definitions]
main.tex: \usemodule[definitions] \starttext blah $\lambdax$ blah. \stoptext
This results in the following compile error:
! Undefined control sequence. \lambdax ->\lambda_x
l.5 blah $\lambdax $ blah. ?
However, if you change "\usemodule[definitions]" into "\input definitions" instead, then there is no compile error! My understanding is that the underscore is a valid character for macro names now outside of math mode, which is what is causing the problem. But I really don't understand what magic is going on in the modules code to trigger this.
I would be very interested in an explanation of what is going on.
You need \normalsubscript in your module. You define a command and in this case it doesn’t matter that you plan to use it in math mode, the _ is now a normal letter like “a” and this won’t change when you call \lambdax in your document.
Write
\def\lambdax{\lambda\normalsubscript x}
and it will work again.
Wolfgang
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Am 14.01.2011 um 10:15 schrieb Mathieu Boespflug:
Thank you for the solution, Wolfgang. But it seems rather painful to have to replace every occurrence of _ in my definitions module with the very verbose \normalsubscript just because it's a module. The new default catcode for _ introduces extra difficulty when defining math macros. Would it be possible to at least have a macro to revert to the old behaviour? Also, I'm still stumped as to why modules make any difference here. I would have expected this problem to also show up if the definitions were made inline at the top of the source file for the document.
When you write a module you put \unprotect and \protect at the begin and end of the file because they make @, !, ? and _ to a normal letter like abc which can be used in macros. When you load a file with \usemodule or \environment this isn’t necessary because context adds already calls both commands when the file is opened and closed for reading and this mechanism is used even if you aren’t aware of this. PS For \environment this is only true when you use it in a document with \starttext or when you write it before \startproduct, \startcomponent etc. PPS You can abuse \nonknuthmode to make your module to work \startbuffer[definitions] \pushcatcodes\nonknuthmode % \startnonknuthmode \def\lambdax{\lambda_x} \popcatcodes % \stopnonknuthmode \stopbuffer \savebuffer[definitions][p-definitions.tex] \startbuffer[more] \def\morex{\more_x} \stopbuffer \savebuffer[more][p-more.tex] \usemodule[definitions,more] \starttext blah $\lambdax$ blah. \morex \stoptext Wolfgang
Hi Wolfgang,
thank you for the explanation and the solution.
Best,
Mathieu
On Fri, Jan 14, 2011 at 10:32 AM, Wolfgang Schuster
Am 14.01.2011 um 10:15 schrieb Mathieu Boespflug:
Thank you for the solution, Wolfgang. But it seems rather painful to have to replace every occurrence of _ in my definitions module with the very verbose \normalsubscript just because it's a module. The new default catcode for _ introduces extra difficulty when defining math macros. Would it be possible to at least have a macro to revert to the old behaviour? Also, I'm still stumped as to why modules make any difference here. I would have expected this problem to also show up if the definitions were made inline at the top of the source file for the document.
When you write a module you put \unprotect and \protect at the begin and end of the file because they make @, !, ? and _ to a normal letter like abc which can be used in macros. When you load a file with \usemodule or \environment this isn’t necessary because context adds already calls both commands when the file is opened and closed for reading and this mechanism is used even if you aren’t aware of this.
PS For \environment this is only true when you use it in a document with \starttext or when you write it before \startproduct, \startcomponent etc.
PPS You can abuse \nonknuthmode to make your module to work
\startbuffer[definitions] \pushcatcodes\nonknuthmode % \startnonknuthmode \def\lambdax{\lambda_x} \popcatcodes % \stopnonknuthmode \stopbuffer
\savebuffer[definitions][p-definitions.tex]
\startbuffer[more] \def\morex{\more_x} \stopbuffer
\savebuffer[more][p-more.tex]
\usemodule[definitions,more]
\starttext blah $\lambdax$ blah. \morex \stoptext
Wolfgang
___________________________________________________________________________________ If your question is of interest to others as well, please add an entry to the Wiki!
maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context webpage : http://www.pragma-ade.nl / http://tex.aanhet.net archive : http://foundry.supelec.fr/projects/contextrev/ wiki : http://contextgarden.net ___________________________________________________________________________________
On 14-1-2011 10:15, Mathieu Boespflug wrote:
Thank you for the solution, Wolfgang. But it seems rather painful to have to replace every occurrence of _ in my definitions module with the very verbose \normalsubscript just because it's a module. The new default catcode for _ introduces extra difficulty when defining math macros. Would it be possible to at least have a macro to revert to the old behaviour? Also, I'm still stumped as to why modules make any difference here. I would have expected this problem to also show up if the definitions were made inline at the top of the source file for the document.
just add a space before the _ when it directly follows a \cs, so ... $\cs _2$ ... but regular text like ... $x_2$ ... can be left as it is Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------
Am 14.01.2011 um 12:01 schrieb Hans Hagen:
just add a space before the _ when it directly follows a \cs, so
... $\cs _2$ ...
but regular text like
... $x_2$ ...
can be left as it is
He put the definitions in a external file which he loads with \usemodule and then this won’t work \starttexcode \def\lambdaone{\lambda_x} \stoptexcode \starttexcode \def\lambdatwo{\lambda _x} \stoptexcode \starttexcode \pushcatcodetable\donknuthmode \def\lambdathree{\lambda_x} \popcatcodes \stoptexcode \starttext \doifmode{one} {$\lambdaone $} \doifmode{two} {$\lambdatwo $} \doifmode{three}{$\lambdathree$} \stoptext 1. context --mode=one test.tex ! Undefined control sequence. \lambdaone ->\lambda_x <argument> $\lambdaone $ \firstofoneargument #1->#1 l.16 \doifmode{one} {$\lambdaone $} ? 2. context --mode=two test.tex ! Undefined control sequence. \lambdatwo ->\lambda _ x <argument> $\lambdatwo $ \firstofoneargument #1->#1 l.17 \doifmode{two} {$\lambdatwo $} ? 3. context --mode=three test.tex -> test.pdf Wolfgang
participants (5)
-
Aditya Mahajan -
Hans Hagen -
Mathieu Boespflug -
Mathieu Boespflug -
Wolfgang Schuster