Document Classes ⇒ Why put @ in command names

[benjibloublou]

Often in class definitions, authors define commands with an "@" in their name, like :

Code: Select all

\rule@vpos
\fromlieu@let@hpos

Does this have a special function? Or is it just the way they separate words in command names?

Thx,
- B.

[Stefan Kottwitz]

The @ character is not allowed in commands defined and used in normal LaTeX documents. However, it's possible to use that character in command names in style files and classes. That's why it's commonly been used for internal macros, which should not be used by authors - it's prevented as it causes an error. However, if you know what you are doing, you can use macro names with @ if you write \makeatletter before and \makeatother afterwards, which makes the @ character legal and the latter switches back to the default.

Stefan

[cgnieder]

I'd like to quote David Carlisle here:

LaTeX does try to encourage a naming scheme

Document level commands (\section) lowercase.

Package interface commands (\DeclareTextCommandDefault) CamelCase.

Package or kernel internal commands (\@text@composite@) lower@case@with@.

TeX primitives (\expandafter) lowercase.

Mostly this convention is not enforced, and of course one might notice that the top and bottom layer using the same convention makes enforcing anything difficult.

Regards