macros
What do newcommand, renewcommand, and providecommand do, and how do they differ?
I think \newcommand overwrites any previously existing command, while \providecommand creates the command only if it does not already exists. Does \renewcommand only work on already extant commands?
Use two #'s.
\newcommand{\hideanslines}{%
\renewcommand{\putansline}[2]{[##2]}%
}
You can, but wouldn't it be simpler to switch to the T1 encoding?
\documentclass{article}
\usepackage[T1,OT1]{fontenc}
\usepackage{libertine}
\DeclareTextCompositeCommand{\'}{OT1}{e}{{\fontencoding{T1}\selectfont\'e}}
\begin{document}
a\accent19 ei % the original one
a\'ei
\end{document}
You can easily extend to all desired combinations using the same pattern. Note that you can even use \'e in the definition, since the encoding will already be T1 in the group, so the combination \'e will use the relative definition.
Best Answer
No, it is not correct.
\newcommanddefines a new command, and makes an error if it is already defined.\renewcommandredefines a predefined command, and makes an error if it is not yet defined.\providecommanddefines a new command if it isn't already defined.If you want to define a command whether it is new or predefined, you can use
\defor