Name clash, “\ifpdf is already defined” between JHEP3.cls and ifpdf.sty [closed]

Question

You might be interested that there seems to be a clash between JHEP3.cls version 3.1.5 (from http://jhep.sissa.it/jhep/help/JHEP/TeXclass/tools_JHEPlog.html) and the ifpdf package. I think both packages use variable \ifpdf, which clashes.

When I compile:

\documentclass{JHEP3}
\usepackage{graphics}

\author{Kuba}
\date{14/12/2012}
\abstract{ble}
\title{ble}
\keywords{ble bel}
\preprint{10932}

\begin{document} ble ble \end{document}

I get

Package ifpdf Error: Name clash, \ifpdf is already defined.

However, when I replace all \ifpdf in JHEP3.cls to \ifpddf, all \pdftrue to \pddftrue, and all \pdffalse to \pddffalse, it works fine!

I will also write to inform JHEP.

Including \let\ifpdf\relax (as suggested in Package ifpdf Error) does not help, because an error message like Extra \fi \begin{document} appears.

Do you have another/better idea, how to deal with this?

Answer 1

Yes, \ifpdf is defined both in the class file and in the package ifpdf that is loaded by graphics.cfg. Workaround:

\RequirePackage{ifpdf}
\documentclass{JHEP3}

Then \ifpdf will be overwritten by the class, but with a similar meaning (the class is wrong for negative numbers of \pdfoutput). But the warning of ifpdf is not triggered and the package will not be loaded again later, because the package is already loaded.

Answer 2

Your example document compiles fine for me, probabably because it does not contain \usepackage{ifpdf}. Other than that, you are right, the JHEP3 class does define \ifpdf. Just don't use package ifpdf with this class. If you have to use some package that loads ifpdf, then insert \let\ifpdf\relax before that, or even directly after the \documentclass{JHEP3}.