Use of noexpand in the implementation of TextOrMath for eTeXWhen to use edef, noexpand, and expandafter?Does...

Can I hook these wires up to find the connection to a dead outlet?

How does a dynamic QR code work?

How exploitable/balanced is this homebrew spell: Spell Permanency?

When handwriting 黄 (huáng; yellow) is it incorrect to have a disconnected 草 (cǎo; grass) radical on top?

Use of noexpand in the implementation of TextOrMath for eTeX

Why was the shrink from 8″ made only to 5.25″ and not smaller (4″ or less)

Do Iron Man suits sport waste management systems?

Do creatures with a speed 0ft., fly 30ft. (hover) ever touch the ground?

What does the same-ish mean?

What is the most common color to indicate the input-field is disabled?

Can compressed videos be decoded back to their uncompresed original format?

How to compare a string

Getting extremely large arrows with tikzcd

In Bayesian inference, why are some terms dropped from the posterior predictive?

Knowledge-based authentication using Domain-driven Design in C#

How can a day be of 24 hours?

Does Dispel Magic work on Tiny Hut?

Unlock My Phone! February 2018

Is it possible to create a QR code using text?

My singleton can be called multiple times

Is it a bad idea to plug the other end of ESD strap to wall ground?

What is the difference between 'contrib' and 'non-free' packages repositories?

GFCI outlets - can they be repaired? Are they really needed at the end of a circuit?

Finitely generated matrix groups whose eigenvalues are all algebraic



Use of noexpand in the implementation of TextOrMath for eTeX


When to use edef, noexpand, and expandafter?Does noexpand have to be a primitive?Problem with nested noexpand and edefReplacement for unexpanded without eTeX extensionWhy do some arguments in a macro need to be preceded by noexpand?How to use noexpand in an edef?Why six noexpand in a row?How can I use noexpand and unexpanded without appending a space to the unexpanded tokens?How should I /protect this command for use in csname?ifx doesn't treat noexpand as relax













4















In latexrelease 2015/01/01, there are two implementations of TextOrMath: one for regular
TeX, the other one for eTeX-like engines (more precisely: those which support protected). My question concerns the latter:



protectedexpandafterdefcsname TextOrMathspaceendcsname{%
(...) } % no problem here
edefTextOrMath#1#2{% from latex.ltx
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}


I think I understand well these definitions, however I can't figure out why the edef isn't simply written this way:



edefTextOrMath#1#2{% from me
csname TextOrMathspaceendcsname
{#1}{#2}}


Since the internal TextOrMath<space> macro is protected, what is the point of preceding it with noexpand inside the edef? Is it because the author feared that protected might be deficient?..



I made a test like this (ran with pdfTeX):



% From latex.ltx (or p. 153 of source2e.pdf)
protectedexpandafterdefcsname TextOrMathspaceendcsname{%
ifmmode expandafter@secondoftwo
else expandafter@firstoftwo fi}

edefTextOrMath#1#2{%
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}

% My simpler way of doing the same (?)
edefaltTextOrMath#1#2{%
csname TextOrMathspaceendcsname
{#1}{#2}}

showTextOrMath % TextOrMath=macro:#1#2->TextOrMath {#1}{#2}.
showaltTextOrMath % altTextOrMath=ditto

ifxTextOrMathaltTextOrMath
identical
else
different
fi

vfill
eject
bye


This test prints 'identical' and seems to indicate that my definition is equivalent to the one in latex.ltx (but slightly simpler). Did I miss something?



Thanks!










share|improve this question























  • thanks I suppose we could change that:-)

    – David Carlisle
    1 hour ago











  • Many thanks for your insight into this, I was really puzzled!

    – frougon
    1 hour ago
















4















In latexrelease 2015/01/01, there are two implementations of TextOrMath: one for regular
TeX, the other one for eTeX-like engines (more precisely: those which support protected). My question concerns the latter:



protectedexpandafterdefcsname TextOrMathspaceendcsname{%
(...) } % no problem here
edefTextOrMath#1#2{% from latex.ltx
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}


I think I understand well these definitions, however I can't figure out why the edef isn't simply written this way:



edefTextOrMath#1#2{% from me
csname TextOrMathspaceendcsname
{#1}{#2}}


Since the internal TextOrMath<space> macro is protected, what is the point of preceding it with noexpand inside the edef? Is it because the author feared that protected might be deficient?..



I made a test like this (ran with pdfTeX):



% From latex.ltx (or p. 153 of source2e.pdf)
protectedexpandafterdefcsname TextOrMathspaceendcsname{%
ifmmode expandafter@secondoftwo
else expandafter@firstoftwo fi}

edefTextOrMath#1#2{%
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}

% My simpler way of doing the same (?)
edefaltTextOrMath#1#2{%
csname TextOrMathspaceendcsname
{#1}{#2}}

showTextOrMath % TextOrMath=macro:#1#2->TextOrMath {#1}{#2}.
showaltTextOrMath % altTextOrMath=ditto

ifxTextOrMathaltTextOrMath
identical
else
different
fi

vfill
eject
bye


This test prints 'identical' and seems to indicate that my definition is equivalent to the one in latex.ltx (but slightly simpler). Did I miss something?



Thanks!










share|improve this question























  • thanks I suppose we could change that:-)

    – David Carlisle
    1 hour ago











  • Many thanks for your insight into this, I was really puzzled!

    – frougon
    1 hour ago














4












4








4








In latexrelease 2015/01/01, there are two implementations of TextOrMath: one for regular
TeX, the other one for eTeX-like engines (more precisely: those which support protected). My question concerns the latter:



protectedexpandafterdefcsname TextOrMathspaceendcsname{%
(...) } % no problem here
edefTextOrMath#1#2{% from latex.ltx
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}


I think I understand well these definitions, however I can't figure out why the edef isn't simply written this way:



edefTextOrMath#1#2{% from me
csname TextOrMathspaceendcsname
{#1}{#2}}


Since the internal TextOrMath<space> macro is protected, what is the point of preceding it with noexpand inside the edef? Is it because the author feared that protected might be deficient?..



I made a test like this (ran with pdfTeX):



% From latex.ltx (or p. 153 of source2e.pdf)
protectedexpandafterdefcsname TextOrMathspaceendcsname{%
ifmmode expandafter@secondoftwo
else expandafter@firstoftwo fi}

edefTextOrMath#1#2{%
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}

% My simpler way of doing the same (?)
edefaltTextOrMath#1#2{%
csname TextOrMathspaceendcsname
{#1}{#2}}

showTextOrMath % TextOrMath=macro:#1#2->TextOrMath {#1}{#2}.
showaltTextOrMath % altTextOrMath=ditto

ifxTextOrMathaltTextOrMath
identical
else
different
fi

vfill
eject
bye


This test prints 'identical' and seems to indicate that my definition is equivalent to the one in latex.ltx (but slightly simpler). Did I miss something?



Thanks!










share|improve this question














In latexrelease 2015/01/01, there are two implementations of TextOrMath: one for regular
TeX, the other one for eTeX-like engines (more precisely: those which support protected). My question concerns the latter:



protectedexpandafterdefcsname TextOrMathspaceendcsname{%
(...) } % no problem here
edefTextOrMath#1#2{% from latex.ltx
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}


I think I understand well these definitions, however I can't figure out why the edef isn't simply written this way:



edefTextOrMath#1#2{% from me
csname TextOrMathspaceendcsname
{#1}{#2}}


Since the internal TextOrMath<space> macro is protected, what is the point of preceding it with noexpand inside the edef? Is it because the author feared that protected might be deficient?..



I made a test like this (ran with pdfTeX):



% From latex.ltx (or p. 153 of source2e.pdf)
protectedexpandafterdefcsname TextOrMathspaceendcsname{%
ifmmode expandafter@secondoftwo
else expandafter@firstoftwo fi}

edefTextOrMath#1#2{%
expandafternoexpandcsname TextOrMathspaceendcsname
{#1}{#2}}

% My simpler way of doing the same (?)
edefaltTextOrMath#1#2{%
csname TextOrMathspaceendcsname
{#1}{#2}}

showTextOrMath % TextOrMath=macro:#1#2->TextOrMath {#1}{#2}.
showaltTextOrMath % altTextOrMath=ditto

ifxTextOrMathaltTextOrMath
identical
else
different
fi

vfill
eject
bye


This test prints 'identical' and seems to indicate that my definition is equivalent to the one in latex.ltx (but slightly simpler). Did I miss something?



Thanks!







macros expansion definition protected-macro






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 3 hours ago









frougonfrougon

641611




641611













  • thanks I suppose we could change that:-)

    – David Carlisle
    1 hour ago











  • Many thanks for your insight into this, I was really puzzled!

    – frougon
    1 hour ago



















  • thanks I suppose we could change that:-)

    – David Carlisle
    1 hour ago











  • Many thanks for your insight into this, I was really puzzled!

    – frougon
    1 hour ago

















thanks I suppose we could change that:-)

– David Carlisle
1 hour ago





thanks I suppose we could change that:-)

– David Carlisle
1 hour ago













Many thanks for your insight into this, I was really puzzled!

– frougon
1 hour ago





Many thanks for your insight into this, I was really puzzled!

– frougon
1 hour ago










1 Answer
1






active

oldest

votes


















3














No you didn't miss anything, just old habits die hard as we gradually add these modern post 1992 features into the sources....






share|improve this answer
























    Your Answer








    StackExchange.ready(function() {
    var channelOptions = {
    tags: "".split(" "),
    id: "85"
    };
    initTagRenderer("".split(" "), "".split(" "), channelOptions);

    StackExchange.using("externalEditor", function() {
    // Have to fire editor after snippets, if snippets enabled
    if (StackExchange.settings.snippets.snippetsEnabled) {
    StackExchange.using("snippets", function() {
    createEditor();
    });
    }
    else {
    createEditor();
    }
    });

    function createEditor() {
    StackExchange.prepareEditor({
    heartbeatType: 'answer',
    autoActivateHeartbeat: false,
    convertImagesToLinks: false,
    noModals: true,
    showLowRepImageUploadWarning: true,
    reputationToPostImages: null,
    bindNavPrevention: true,
    postfix: "",
    imageUploader: {
    brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
    contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
    allowUrls: true
    },
    onDemand: true,
    discardSelector: ".discard-answer"
    ,immediatelyShowMarkdownHelp:true
    });


    }
    });














    draft saved

    draft discarded


















    StackExchange.ready(
    function () {
    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2ftex.stackexchange.com%2fquestions%2f482829%2fuse-of-noexpand-in-the-implementation-of-textormath-for-etex%23new-answer', 'question_page');
    }
    );

    Post as a guest















    Required, but never shown

























    1 Answer
    1






    active

    oldest

    votes








    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3














    No you didn't miss anything, just old habits die hard as we gradually add these modern post 1992 features into the sources....






    share|improve this answer




























      3














      No you didn't miss anything, just old habits die hard as we gradually add these modern post 1992 features into the sources....






      share|improve this answer


























        3












        3








        3







        No you didn't miss anything, just old habits die hard as we gradually add these modern post 1992 features into the sources....






        share|improve this answer













        No you didn't miss anything, just old habits die hard as we gradually add these modern post 1992 features into the sources....







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered 2 hours ago









        David CarlisleDavid Carlisle

        497k4111441891




        497k4111441891






























            draft saved

            draft discarded




















































            Thanks for contributing an answer to TeX - LaTeX Stack Exchange!


            • Please be sure to answer the question. Provide details and share your research!

            But avoid



            • Asking for help, clarification, or responding to other answers.

            • Making statements based on opinion; back them up with references or personal experience.


            To learn more, see our tips on writing great answers.




            draft saved


            draft discarded














            StackExchange.ready(
            function () {
            StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2ftex.stackexchange.com%2fquestions%2f482829%2fuse-of-noexpand-in-the-implementation-of-textormath-for-etex%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown





















































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown

































            Required, but never shown














            Required, but never shown












            Required, but never shown







            Required, but never shown







            Popular posts from this blog

            Gersau Kjelder | Navigasjonsmeny46°59′0″N 8°31′0″E46°59′0″N...

            Nässjö kommun Tettstader | Kjelder | NavigasjonsmenyeVIAFISNIGeoNamesMusicBrainz (area)

            Kvitkval Innhaldsliste Taksonomi og utvikling | Utsjånad og levevis | Utbreiing | Åtferd |...