Btukfyl

Say I have written two commands, CommandA and CommandB. I wish to have a third command that takes inputs to determines which of the two previous commands to execute. Very naively this how I would try and accomplish this as shown below, however, it does not work.

newcommand{CommandA}{

    hspace{5mm}

}

newcommand{CommandB}{

    vspace{5mm}

}

newcommand{C}[1]{

    Command#1

}

So if I call C{A}, as written I would really execute CommandA.

For a normal user, this is probably the easiest to understand

usepackage{etoolbox}

newcommand{CommandA}{%

    hspace{5mm}%

}

newcommand{CommandB}{%

    vspace{5mm}%

}

newcommandC[1]{%

   csuse{Command#1}%

}

csuse builds a macro name, and calls it

It makes sense to define families of such commands.

documentclass{article}

usepackage{xparse}



ExplSyntaxOn

NewDocumentCommand{defineobject}{mm}

 {

  prop_new:c { g_garth_#1_prop }

  prop_gset_from_keyval:cn { g_garth_#1_prop } { #2 }

 }



NewDocumentCommand{getobject}{mm}

 {% #1 = object name, #2 = variable or string

  prop_item:cf { g_garth_#1_prop } { #2 }

 }

cs_generate_variant:Nn prop_item:Nn { cf }

ExplSyntaxOff



defineobject{C}{

  A=hspace{5mm},

  B=vspace{5mm}

}

newcommand{C}[1]{getobject{C}{#1}}



begin{document}



XC{A}YC{B}



XYZ



end{document}

This might turn to be useful for the similar problem in Can you create concatenate variable names in LaTex?

documentclass[12pt]{exam}

usepackage{xparse}



ExplSyntaxOn

NewDocumentCommand{defineobject}{mm}

 {

  prop_new:c { g_garth_#1_prop }

  prop_gset_from_keyval:cn { g_garth_#1_prop } { #2 }

 }



NewDocumentCommand{getobject}{mm}

 {% #1 = object name, #2 = variable or string

  prop_item:cf { g_garth_#1_prop } { #2 }

 }

cs_generate_variant:Nn prop_item:Nn { cf }

ExplSyntaxOff



defineobject{fun}{

  A={$s(t) = 12t^2 -7t + 16$},

  B={$s(t) = 16t^2 +3t + 10$},

  C={$s(t) = 12t^2 + t + 10.$}

}



newcommand{exam}{A}



begin{document}



begin{questions}



question

The position of an object moving along a straight line is given by 

getobject{fun}{exam}. Find the average velocity of the object over 

the interval $[1,1+h]$ where $h>0$ is a real number.



renewcommand{exam}{B} % just for testing



question

The position of an object moving along a straight line is given by 

getobject{fun}{exam}. Find the average velocity of the object over 

the interval $[1,1+h]$ where $h>0$ is a real number.



end{questions}



end{document}

The second question has a modified exam just to test whether the expected output is obtained. You can define as many objects as you want. If one has just one variable exam, it also makes sense to define a shorthand:

newcommand{obj}[1]{getobject{#1}{exam}}

and then the calls above can be more simply obj{fun}.

documentclass{article}



newcommandexchange[2]{#2#1}%

newcommandname{}%

longdefname#1#{romannumeral0innername{#1}}%

newcommandinnername[2]{%

   expandafterexchangeexpandafter{csname#2endcsname}{ #1}%

}%



namenewcommand{CommandA}{%

    hspace{5mm}%

}



namenewcommand{CommandB}{%

    vspace{5mm}%

}



namenewcommand{C}[1]{%

    name{Command#1}%

}



begin{document}



hbox{hbox{X}C{A}hbox{X}}%

C{B}%

hbox{hbox{X}C{A}hbox{X}}%



end{document}