persian-tex/iftex — pull request #1 by jcsalomon (2013-06-12 15:13:10+00:00)
Title: Add \ifLuaOrXeTeX and \RequireLuaOrXeTeX

For many purposes, _e.g._, to decide whether to load `fontspec` & `unicode-math`, LuaTeX and XeTeX are interchangable. A unified conditional will eliminate the need for code duplication.