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Process LaTeX code only if package is loaded

4

I would like to create a document used to test diverse packages, and I was wondering if it was possible to use a command so that part of the code is read only if the corresponding package is loaded. I've come up with this but it throws an error which I don't know how to fix.

documentclass{article}

usepackage[utf8]{inputenc}



makeatletter

newcommand{IfPackageLoaded}[3]{@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

I get this error:

! LaTeX Error: Can be used only in preamble.



See the LaTeX manual or LaTeX Companion for explanation.

Type  H <return>  for immediate help.

 ...                                              



l.10 IfPackageLoaded{natbib}{natbib loaded}

                                            {natbib not loaded}

Your command was ignored.

Type  I <command> <return>  to replace it with another command,

or  <return>  to continue without it.

I also know that the command ltx@ifpackageloaded exists when loading the package ltxcmds but when I try to use it in

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



begin{document}

ltx@ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

I get this error message:

! Undefined control sequence.

l.11 ltx

         @ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

The control sequence at the end of the top line

of your error message was never def'ed. If you have

misspelled it (e.g., `hobx'), type `I' and the correct

spelling (e.g., `Ihbox'). Otherwise just continue,

and I'll forget about whatever was undefined.

Can someone please point out what I did wrong?

EDIT: changed documentclass from minimal to article.

packages

share|improve this question

edited yesterday

lashoun

asked yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  You are missing the makeatletter in your second example. And don't use the minimal class, normally it is too minimal.
  
  – Ulrike Fischer
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Read more: tex.stackexchange.com/q/8351/156344
  
  – JouleV
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It is said in the ltxcmds documentation that ltx@ifpackageloaded can be used after begin{document} though.
  
  – lashoun
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  But even then it can only be used if you wrap it in makeatletter...makeatother because it has an @ in its name.
  
  – moewe
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oooh, that's why! I'll try then.
  
  – lashoun
  yesterday
  

  
  
  
  

add a comment | 

4

I would like to create a document used to test diverse packages, and I was wondering if it was possible to use a command so that part of the code is read only if the corresponding package is loaded. I've come up with this but it throws an error which I don't know how to fix.

documentclass{article}

usepackage[utf8]{inputenc}



makeatletter

newcommand{IfPackageLoaded}[3]{@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

I get this error:

! LaTeX Error: Can be used only in preamble.



See the LaTeX manual or LaTeX Companion for explanation.

Type  H <return>  for immediate help.

 ...                                              



l.10 IfPackageLoaded{natbib}{natbib loaded}

                                            {natbib not loaded}

Your command was ignored.

Type  I <command> <return>  to replace it with another command,

or  <return>  to continue without it.

I also know that the command ltx@ifpackageloaded exists when loading the package ltxcmds but when I try to use it in

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



begin{document}

ltx@ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

I get this error message:

! Undefined control sequence.

l.11 ltx

         @ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

The control sequence at the end of the top line

of your error message was never def'ed. If you have

misspelled it (e.g., `hobx'), type `I' and the correct

spelling (e.g., `Ihbox'). Otherwise just continue,

and I'll forget about whatever was undefined.

Can someone please point out what I did wrong?

EDIT: changed documentclass from minimal to article.

packages

share|improve this question

edited yesterday

lashoun

asked yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  You are missing the makeatletter in your second example. And don't use the minimal class, normally it is too minimal.
  
  – Ulrike Fischer
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Read more: tex.stackexchange.com/q/8351/156344
  
  – JouleV
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  It is said in the ltxcmds documentation that ltx@ifpackageloaded can be used after begin{document} though.
  
  – lashoun
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  But even then it can only be used if you wrap it in makeatletter...makeatother because it has an @ in its name.
  
  – moewe
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Oooh, that's why! I'll try then.
  
  – lashoun
  yesterday
  

  
  
  
  

add a comment | 

I would like to create a document used to test diverse packages, and I was wondering if it was possible to use a command so that part of the code is read only if the corresponding package is loaded. I've come up with this but it throws an error which I don't know how to fix.

documentclass{article}

usepackage[utf8]{inputenc}



makeatletter

newcommand{IfPackageLoaded}[3]{@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

I get this error:

! LaTeX Error: Can be used only in preamble.



See the LaTeX manual or LaTeX Companion for explanation.

Type  H <return>  for immediate help.

 ...                                              



l.10 IfPackageLoaded{natbib}{natbib loaded}

                                            {natbib not loaded}

Your command was ignored.

Type  I <command> <return>  to replace it with another command,

or  <return>  to continue without it.

I also know that the command ltx@ifpackageloaded exists when loading the package ltxcmds but when I try to use it in

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



begin{document}

ltx@ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

I get this error message:

! Undefined control sequence.

l.11 ltx

         @ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

The control sequence at the end of the top line

of your error message was never def'ed. If you have

misspelled it (e.g., `hobx'), type `I' and the correct

spelling (e.g., `Ihbox'). Otherwise just continue,

and I'll forget about whatever was undefined.

Can someone please point out what I did wrong?

EDIT: changed documentclass from minimal to article.

packages

share|improve this question

edited yesterday

lashoun

asked yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

documentclass{article}

usepackage[utf8]{inputenc}



makeatletter

newcommand{IfPackageLoaded}[3]{@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

! LaTeX Error: Can be used only in preamble.



See the LaTeX manual or LaTeX Companion for explanation.

Type  H <return>  for immediate help.

 ...                                              



l.10 IfPackageLoaded{natbib}{natbib loaded}

                                            {natbib not loaded}

Your command was ignored.

Type  I <command> <return>  to replace it with another command,

or  <return>  to continue without it.

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



begin{document}

ltx@ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

! Undefined control sequence.

l.11 ltx

         @ifpackageloaded{natbib}{natbib loaded}{natbib not loaded}

The control sequence at the end of the top line

of your error message was never def'ed. If you have

misspelled it (e.g., `hobx'), type `I' and the correct

spelling (e.g., `Ihbox'). Otherwise just continue,

and I'll forget about whatever was undefined.

share|improve this question

edited yesterday

lashoun

asked yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited yesterday

lashoun

asked yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked yesterday

lashounlashoun

615

1 Answer
1

active

oldest

votes

4

As users Ulrike Fischer and moewe pointed out, this works:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



makeatletter

newcommand{IfPackageLoaded}[3]{ltx@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

share|improve this answer

edited yesterday

Schweinebacke

22.5k4577

answered yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  BTW: The [3] is not needed. You can simply use newcommand*{IfPackageLoaded}{ltx@ifpackageloaded}.
  
  – Schweinebacke
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Schweinebacke RIght; also letIfPackageLoadedltx@ifpackageloaded
  
  – egreg
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @egreg Yes, because ltx@ifpackageloaded is a simple macro. If it would be, e.g., robust, it could be better to use LetLtxMacro from package letltxmacro. I didn't want to explain all this, so I've only noted about using newcommand* without arguments.
  
  – Schweinebacke
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the precisions
  
  – lashoun
  yesterday
  

  
  
  
  

add a comment | 

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4

As users Ulrike Fischer and moewe pointed out, this works:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



makeatletter

newcommand{IfPackageLoaded}[3]{ltx@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

share|improve this answer

edited yesterday

Schweinebacke

22.5k4577

answered yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  BTW: The [3] is not needed. You can simply use newcommand*{IfPackageLoaded}{ltx@ifpackageloaded}.
  
  – Schweinebacke
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Schweinebacke RIght; also letIfPackageLoadedltx@ifpackageloaded
  
  – egreg
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @egreg Yes, because ltx@ifpackageloaded is a simple macro. If it would be, e.g., robust, it could be better to use LetLtxMacro from package letltxmacro. I didn't want to explain all this, so I've only noted about using newcommand* without arguments.
  
  – Schweinebacke
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the precisions
  
  – lashoun
  yesterday
  

  
  
  
  

add a comment | 

4

As users Ulrike Fischer and moewe pointed out, this works:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



makeatletter

newcommand{IfPackageLoaded}[3]{ltx@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

share|improve this answer

edited yesterday

Schweinebacke

22.5k4577

answered yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  2
  

  
  
  
  
  
  

  
  
  BTW: The [3] is not needed. You can simply use newcommand*{IfPackageLoaded}{ltx@ifpackageloaded}.
  
  – Schweinebacke
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Schweinebacke RIght; also letIfPackageLoadedltx@ifpackageloaded
  
  – egreg
  yesterday
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @egreg Yes, because ltx@ifpackageloaded is a simple macro. If it would be, e.g., robust, it could be better to use LetLtxMacro from package letltxmacro. I didn't want to explain all this, so I've only noted about using newcommand* without arguments.
  
  – Schweinebacke
  yesterday
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks for the precisions
  
  – lashoun
  yesterday
  

  
  
  
  

add a comment | 

As users Ulrike Fischer and moewe pointed out, this works:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



makeatletter

newcommand{IfPackageLoaded}[3]{ltx@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

share|improve this answer

edited yesterday

Schweinebacke

22.5k4577

answered yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{ltxcmds}



makeatletter

newcommand{IfPackageLoaded}[3]{ltx@ifpackageloaded{#1}{#2}{#3}}

makeatother



begin{document}

IfPackageLoaded{natbib}{natbib loaded}{natbib not loaded}

end{document}

share|improve this answer

edited yesterday

Schweinebacke

22.5k4577

answered yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited yesterday

Schweinebacke

22.5k4577

edited yesterday

Schweinebacke

22.5k4577

answered yesterday

lashounlashoun

615

New contributor

lashoun is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

answered yesterday

lashounlashoun

615