We consider it good practice, when writing packages and classes, to use LATEX commands as much as possible.
Thus, instead of using || and ||.
If you need to set or change the value of a dimen or skip register, use ||.
To manipulate boxes, use LATEX commands such as | |, || and || rather than | |, || and ||.
Use ||, || or || (or the equivalent class commands) rather than |latexerr|, |warning| or ||.
It is still possible to declare options by defining |@<option>| and calling |options|; but we recommend the || and || commands instead. These are more powerful and use less memory. So rather than using:
\def\ds@draft{\overfullrule 5pt}
\@options
you should use:
\DeclareOption{draft}{\setlength{\overfullrule}{5pt}}
\ProcessOptions
The advantage of this kind of practice is that your code is more readable and, more important, that it is less likely to break when used with future versions of LATEX.