LaTeX: Why are digits allowed in environments, but forbidden in commands? The 2019 Stack Overflow Developer Survey Results Are InWhat exactly do csname and endcsname do?Why are some characters not allowed in command sequencesWhy does LaTeX make a distinction between commands and environments?Do all starred commands have anything in common?Why are some characters not allowed in command sequencesSuggestions for an automatic taxonomy environmentUse a character other than the backslash for commandsWhy are LaTeX macros so inconsistent?Are end… macro names reserved in LaTeX2e?Can't use command with square brackets in matrix environmentHow to control conditional statements within new commands and environmentsCreating Commands which Make New Environments
Can a flute soloist sit?
What's the name of these plastic connectors
Worn-tile Scrabble
Loose spokes after only a few rides
Inverse Relationship Between Precision and Recall
What do I do when my TA workload is more than expected?
Why couldn't they take pictures of a closer black hole?
What is the most efficient way to store a numeric range?
If I can cast sorceries at instant speed, can I use sorcery-speed activated abilities at instant speed?
Slides for 30 min~1 hr Skype tenure track application interview
Why can't devices on different VLANs, but on the same subnet, communicate?
Does adding complexity mean a more secure cipher?
Did Scotland spend $250,000 for the slogan "Welcome to Scotland"?
Ubuntu Server install with full GUI
If a sorcerer casts the Banishment spell on a PC while in Avernus, does the PC return to their home plane?
Match Roman Numerals
Flight paths in orbit around Ceres?
Dropping list elements from nested list after evaluation
Is an up-to-date browser secure on an out-of-date OS?
Can you cast a spell on someone in the Ethereal Plane, if you are on the Material Plane and have the True Seeing spell active?
Is it correct to say the Neural Networks are an alternative way of performing Maximum Likelihood Estimation? if not, why?
Old scifi movie from the 50s or 60s with men in solid red uniforms who interrogate a spy from the past
Keeping a retro style to sci-fi spaceships?
Deal with toxic manager when you can't quit
LaTeX: Why are digits allowed in environments, but forbidden in commands?
The 2019 Stack Overflow Developer Survey Results Are InWhat exactly do csname and endcsname do?Why are some characters not allowed in command sequencesWhy does LaTeX make a distinction between commands and environments?Do all starred commands have anything in common?Why are some characters not allowed in command sequencesSuggestions for an automatic taxonomy environmentUse a character other than the backslash for commandsWhy are LaTeX macros so inconsistent?Are end… macro names reserved in LaTeX2e?Can't use command with square brackets in matrix environmentHow to control conditional statements within new commands and environmentsCreating Commands which Make New Environments
Finding out that I can have an environment named env2, but no command cmd2, I read Why are some characters not allowed in command sequences, but still I wonder:
Why are digits allowed in environments, but forbidden in commands? In my understanding digits delimit command names (inherited from plain TeX), but why doesn't that restriction apply to environments? Wouldn't it have been more consistent to forbid digits in environment names as well?
macros environments
asked Apr 5 at 22:32
U. WindlU. Windl
1718
add a comment |
Finding out that I can have an environment named env2, but no command cmd2, I read Why are some characters not allowed in command sequences, but still I wonder:
Why are digits allowed in environments, but forbidden in commands? In my understanding digits delimit command names (inherited from plain TeX), but why doesn't that restriction apply to environments? Wouldn't it have been more consistent to forbid digits in environment names as well?
macros environments
asked Apr 5 at 22:32
U. WindlU. Windl
1718
You actually can use numbers in commands. If you doexpandafterdefcsname mycommandwithanumber123456endcsnameyou'll define a commandmycommandwithanumber123456. The environments are created using thecsname...endcsnamepair, so it's fine.
– Phelype Oleinik
Apr 5 at 22:36
expandafterdefcsname macro2endcsnamecommand outputis valid syntax. You then must use it viacsname macro2endcsname.
– Steven B. Segletes
Apr 5 at 22:36
So the answer is "There are not forbidden, but they have to be used in a special way. Still it's recommended not to use them."?
– U. Windl
Apr 5 at 22:41
add a comment |
Finding out that I can have an environment named env2, but no command cmd2, I read Why are some characters not allowed in command sequences, but still I wonder:
Why are digits allowed in environments, but forbidden in commands? In my understanding digits delimit command names (inherited from plain TeX), but why doesn't that restriction apply to environments? Wouldn't it have been more consistent to forbid digits in environment names as well?
macros environments
asked Apr 5 at 22:32
U. WindlU. Windl
1718
Finding out that I can have an environment named env2, but no command cmd2, I read Why are some characters not allowed in command sequences, but still I wonder:
Why are digits allowed in environments, but forbidden in commands? In my understanding digits delimit command names (inherited from plain TeX), but why doesn't that restriction apply to environments? Wouldn't it have been more consistent to forbid digits in environment names as well?
macros environments
macros environments
asked Apr 5 at 22:32
U. WindlU. Windl
1718
asked Apr 5 at 22:32
U. WindlU. Windl
1718
asked Apr 5 at 22:32
U. WindlU. Windl
1718
asked Apr 5 at 22:32
U. WindlU. Windl
1718
asked Apr 5 at 22:32
U. WindlU. Windl
1718
1718
You actually can use numbers in commands. If you doexpandafterdefcsname mycommandwithanumber123456endcsnameyou'll define a commandmycommandwithanumber123456. The environments are created using thecsname...endcsnamepair, so it's fine.
– Phelype Oleinik
Apr 5 at 22:36
expandafterdefcsname macro2endcsnamecommand outputis valid syntax. You then must use it viacsname macro2endcsname.
– Steven B. Segletes
Apr 5 at 22:36
So the answer is "There are not forbidden, but they have to be used in a special way. Still it's recommended not to use them."?
– U. Windl
Apr 5 at 22:41
add a comment |
You actually can use numbers in commands. If you doexpandafterdefcsname mycommandwithanumber123456endcsnameyou'll define a commandmycommandwithanumber123456. The environments are created using thecsname...endcsnamepair, so it's fine.
– Phelype Oleinik
Apr 5 at 22:36
expandafterdefcsname macro2endcsnamecommand outputis valid syntax. You then must use it viacsname macro2endcsname.
– Steven B. Segletes
Apr 5 at 22:36
So the answer is "There are not forbidden, but they have to be used in a special way. Still it's recommended not to use them."?
– U. Windl
Apr 5 at 22:41
You actually can use numbers in commands. If you do
expandafterdefcsname mycommandwithanumber123456endcsname you'll define a command mycommandwithanumber123456. The environments are created using the csname...endcsname pair, so it's fine.– Phelype Oleinik
Apr 5 at 22:36
You actually can use numbers in commands. If you do
expandafterdefcsname mycommandwithanumber123456endcsname you'll define a command mycommandwithanumber123456. The environments are created using the csname...endcsname pair, so it's fine.– Phelype Oleinik
Apr 5 at 22:36
expandafterdefcsname macro2endcsnamecommand output is valid syntax. You then must use it via csname macro2endcsname.– Steven B. Segletes
Apr 5 at 22:36
expandafterdefcsname macro2endcsnamecommand output is valid syntax. You then must use it via csname macro2endcsname.– Steven B. Segletes
Apr 5 at 22:36
So the answer is "There are not forbidden, but they have to be used in a special way. Still it's recommended not to use them."?
– U. Windl
Apr 5 at 22:41
So the answer is "There are not forbidden, but they have to be used in a special way. Still it's recommended not to use them."?
– U. Windl
Apr 5 at 22:41
add a comment |
1 Answer
1
active
oldest
votes
The restriction is in the scanner, tex's "eyes" in the texbook terminology. Any sequence of characters may be used as a command name, however after a character of catcode 0 (normally ) then tex scans the next non-letter (character of catcode other than 11) or a contiguous sequence of letters, and tokenizes it as a single csname token.
This means that foo123 normally parses as the token foo followed by the three tokens 1, 2, 3. Unless you make digits catcode 11. Similarly section* is normally the token section followed by the token *.
environment names use do not require to parse the name via the escape character, (they use the csname primitive but that's an implementation detail so begintabular accesses tabular but begintabular* accesses the command with name tabular* (not the two tokens that would normally be generated by parsing tabular*).
So technically it would be quite hard to not allow digits (or other characters) in environment names, especially when latex was designed there was not the memory available to add that kind of character-by-character check.
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
add a comment |
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
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2ftex.stackexchange.com%2fquestions%2f483440%2flatex-why-are-digits-allowed-in-environments-but-forbidden-in-commands%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
The restriction is in the scanner, tex's "eyes" in the texbook terminology. Any sequence of characters may be used as a command name, however after a character of catcode 0 (normally ) then tex scans the next non-letter (character of catcode other than 11) or a contiguous sequence of letters, and tokenizes it as a single csname token.
This means that foo123 normally parses as the token foo followed by the three tokens 1, 2, 3. Unless you make digits catcode 11. Similarly section* is normally the token section followed by the token *.
environment names use do not require to parse the name via the escape character, (they use the csname primitive but that's an implementation detail so begintabular accesses tabular but begintabular* accesses the command with name tabular* (not the two tokens that would normally be generated by parsing tabular*).
So technically it would be quite hard to not allow digits (or other characters) in environment names, especially when latex was designed there was not the memory available to add that kind of character-by-character check.
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
add a comment |
The restriction is in the scanner, tex's "eyes" in the texbook terminology. Any sequence of characters may be used as a command name, however after a character of catcode 0 (normally ) then tex scans the next non-letter (character of catcode other than 11) or a contiguous sequence of letters, and tokenizes it as a single csname token.
This means that foo123 normally parses as the token foo followed by the three tokens 1, 2, 3. Unless you make digits catcode 11. Similarly section* is normally the token section followed by the token *.
environment names use do not require to parse the name via the escape character, (they use the csname primitive but that's an implementation detail so begintabular accesses tabular but begintabular* accesses the command with name tabular* (not the two tokens that would normally be generated by parsing tabular*).
So technically it would be quite hard to not allow digits (or other characters) in environment names, especially when latex was designed there was not the memory available to add that kind of character-by-character check.
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
add a comment |
The restriction is in the scanner, tex's "eyes" in the texbook terminology. Any sequence of characters may be used as a command name, however after a character of catcode 0 (normally ) then tex scans the next non-letter (character of catcode other than 11) or a contiguous sequence of letters, and tokenizes it as a single csname token.
This means that foo123 normally parses as the token foo followed by the three tokens 1, 2, 3. Unless you make digits catcode 11. Similarly section* is normally the token section followed by the token *.
environment names use do not require to parse the name via the escape character, (they use the csname primitive but that's an implementation detail so begintabular accesses tabular but begintabular* accesses the command with name tabular* (not the two tokens that would normally be generated by parsing tabular*).
So technically it would be quite hard to not allow digits (or other characters) in environment names, especially when latex was designed there was not the memory available to add that kind of character-by-character check.
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
The restriction is in the scanner, tex's "eyes" in the texbook terminology. Any sequence of characters may be used as a command name, however after a character of catcode 0 (normally ) then tex scans the next non-letter (character of catcode other than 11) or a contiguous sequence of letters, and tokenizes it as a single csname token.
This means that foo123 normally parses as the token foo followed by the three tokens 1, 2, 3. Unless you make digits catcode 11. Similarly section* is normally the token section followed by the token *.
environment names use do not require to parse the name via the escape character, (they use the csname primitive but that's an implementation detail so begintabular accesses tabular but begintabular* accesses the command with name tabular* (not the two tokens that would normally be generated by parsing tabular*).
So technically it would be quite hard to not allow digits (or other characters) in environment names, especially when latex was designed there was not the memory available to add that kind of character-by-character check.
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
edited Apr 5 at 23:24
Phelype Oleinik
25k54690
25k54690
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
answered Apr 5 at 23:19
David CarlisleDavid Carlisle
498k4111441893
498k4111441893
add a comment |
add a comment |
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.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2ftex.stackexchange.com%2fquestions%2f483440%2flatex-why-are-digits-allowed-in-environments-but-forbidden-in-commands%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
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
You actually can use numbers in commands. If you do
expandafterdefcsname mycommandwithanumber123456endcsnameyou'll define a commandmycommandwithanumber123456. The environments are created using thecsname...endcsnamepair, so it's fine.– Phelype Oleinik
Apr 5 at 22:36
expandafterdefcsname macro2endcsnamecommand outputis valid syntax. You then must use it viacsname macro2endcsname.– Steven B. Segletes
Apr 5 at 22:36
So the answer is "There are not forbidden, but they have to be used in a special way. Still it's recommended not to use them."?
– U. Windl
Apr 5 at 22:41