Is it possible to auto infer macros which have a common prefix?

Question

Let say that I have the following code:

\documentclass{article}

\usepackage{xspace}

\def\cal#1{\ensuremath{\mathcal{#1}}\xspace}
\newcommand{\calA}{\cal A}

\begin{document}

Let \calA be a linearly ordered set.

\end{document}

Now, imagine that I need to use a lot mathcal for single letters, how can I make latex auto infer/auto generate the definition for the \calX where X is a capital letter. Of course, I could generate 26 newcommands but I would prefer not to do that.

I mean that I would like that I had not to put a space between \cal and X. Is there any trick available to do that?

Answer 1

A control sequence is either defined or undefined. There's no way to say

Hey, TeX, if you find a control sequence starting with \cal followed by an uppercase letter, say X, and which is currently undefined, define it so that it does \mathcal{X}.

Well, there might be some very fragile ways to do it. The trade between using complex and fragile code or defining the macros you need is in favor of the latter.

It's much simpler to use code suggested for Automatically generate new commands or the code in https://tex.stackexchange.com/a/207992/4427 for batch defining the macros you need.

About \ensuremath and \xspace, I recommend sticking instead to $\calA$, that's not much harder to type and carries more semantics.

Answer 2

\documentclass{article}
\usepackage{listofitems,xspace}
\newcommand\makecalx[1]{%
  \expandafter\def\csname cal#1\endcsname{\ensuremath{\mathcal{#1}}\xspace}%
}
\readlist\callets{A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z}
\foreachitem\z\in\callets[]{\expandafter\makecalx\expandafter{\z}}
\begin{document}
Here is \calG and \calZ.
\end{document}