General ⇒ Internal vs external macros

[erwann]

Novice question on programming.

Code: Select all

\newcommand{\foo}{\ohmy@foo}

If I run this, I get undefined control sequence \foo->ohmy@foo. External/Internal macros live in totally separate worlds? Ins't there a wormhole? I another words, why am I missing about about this aspect of LaTeX programming?

[Johannes_B]

https://tex.stackexchange.com/questions ... atother-do

[Stefan Kottwitz]

Hello Erwann!

The @ is to prevent accidental use of internal macros. Thorsten gave a good summary:

The \makeatletter command temporarily defines »@« as a normal character to enable changes to internal LaTeX macros outside packages (STY) or classes (CLS). With \makeatother this process is reversed and the »@« is set to its original character category (other). The »@« is used to protect the internal LaTeX macros. Hence you should be very careful when using these two commands.

Then:

• \@ and @ in macro names and \spacefactor complaints
• section on commands
• section on commands
• Tuglist: Makeatletter and Makeatother

From here.

Stefan

[erwann]

Than u. My bad, I shld have specified within a *.dtx. Solved: I forgot to run *.ins.