General ⇒ Is there a "providecommand"-like cmd for counter & length?

[yoyoimut]

Is there a command that behaves like "\providecommand" but to define a counter or length ?


thank you in advance.


regards,

Yuko

[josephwright]

Not in the kernel: you want something like:

Code: Select all

\makeatletter
\newcommand*\providecounter[1]{%
  \@ifundefined{c@#1}%
    {\@definecounter{#1}}%
    {}%
}
\makeatother

[yoyoimut]

Thanks Joseph Wright,

The counter works well.

I tried to modify your code for the length but it did not work.


Thank you in advance.


regards,

Yuko.

[josephwright]

Well, LaTeX lengths are just TeX skips, so

Code: Select all

\makeatletter
\newcommand*\providelength[1]{%
  \begingroup
    \escapechar\m@ne
    \xdef\@gtempa{\string#1}%
  \endgroup
  \@ifundefined{\@gtempa}%
    {\newskip#1}%
    {}%
}
\makeatother

The extra code here is needed as \@ifundefined needs the name of the new length (for example "mylength") and not the token ("\mylength"). See the same approach in \providecommand.

[yoyoimut]

Thank Joseph Wright,

The code works well.

I am sorry, actually I have one more

I need \providesavebox associated with \newsavebox.

Should I create a new topic for this question?


Thank you in advance.


regards,

Yuko.