Redefine existing commands outside preamble

Question

I have a Latex document where a lot of the text and figures is generated automatically by a program. In a minimal example, the final document is like this:

\documentclass{memoir}

%% This file is generated automatically, and is full of
%% \newcommand definitions
\input{variables}

\begin{document}
  \input{text} % makes heavy use of commands defined in variables.tex
\end{document}

The program that generates the variables.tex file has multiple options which change the return value of the Latex commands it defines. This means that I can always use the same document as structure but control the actual content from variables.tex.

Now I want to have text.tex twice in the same document, each time using a variables-X.tex file built with different options. However, they both define different commands with the same name.

I would go about doing this? In my mind would be something like:

\documentclass{memoir}
\begin{document}

  \input{variables-1}
  \input{text}

  \input{variables-2}
  \input{text}

\end{document}

But that fails with "Command \SequencesDate already defined." (this is one of the commands defined inside variables.tex). If instead of \newcommand I use \renewcommand, I get a "\SequencesDate undefined" error.

My actual case is a bit more complicated. I hope this doesn't add extra noise to the question but I guess it may have some impact on what can be done. The commands defined in the variables.tex are mainly numeric with a grey background. But these commands are still used in operations involving the fp package and that is done by redefining the command that controls the background. Like this:

File variables.tex

\newcommand{\Foo}{\ScriptValue{5.3}}
\newcommand{\Bar}{\ScriptValue{5.6}}

File text.tex

\FPmin{\MinFooBar}{\Foo}{\Bar}
The smallest foobar is \MinFooBar

File document.tex

\documentclass{memoir}
\usepackage{color}
\usepackage{fp}

\input{variables}

%% Color automatic values with grey background
\newcommand{\ScriptValue}[1]{\setlength{\fboxsep}{0pt}\colorbox[gray]{0.8}{\strut #1}}

%% We also want to make operations with those values in LaTeX
%% using FPeval but FPeval fails because ScriptValue gets expanded into
%% something non-numeric.  So we use the following trick: we store the
%% original ScriptValue and FPeval macros, and then replace FPeval with
%% something that temporarily disables ScriptValue while we call the
%% original FPeval.
%% See https://tex.stackexchange.com/questions/159155/identify-pieces-of-text-automatically-generated-from-input-and-new-command
%% and https://tex.stackexchange.com/questions/283655/overloading-functions-of-the-fp-package

\let\RealScriptValue\ScriptValue

\let\RealFPmin\FPmin
\renewcommand{\FPmin}[3]{%
  \renewcommand{\ScriptValue}[1]{##1}%
  \RealFPmin{\UnmarkedResult}{#2}{#3}%
  \edef#1{\noexpand\ScriptValue{\UnmarkedResult}}%
  \renewcommand{\ScriptValue}{\RealScriptValue}%
}


\begin{document}
  \input{text}
\end{document}

Answer 1

Let your 'variables.tex' - generator do a loop and say for each of the defined commands \foo etc. \let\foo\relax etc.

This way it is undefined at the top of each input of the variables.tex Another way: Use \undef{\foo} or \csundef{foo} from etoolbox package.

variables.tex

\let\foo\relax
\let\foobar\relax
\newcommand{\foo}{Foo}
\newcommand{\foobar}{Foobar}

Driver

\documentclass{memoir}

%% This file is generated automatically, and is full of
%% \newcommand definitions

\begin{document}

  \input{variables}

  \input{text} % makes heavy use of commands defined in variables.tex


  \input{variables}% It will do here too with the same file 

  \input{text} % makes heavy use of commands defined in variables.tex

\end{document}

text.tex

\foo\ and \foobar\ are nice commands

Update

Another approach without tedious \let\foo\relax statements:

Use

\begingroup
\input{variables-1}
\input{text}
\endgroup

for each of the relevant cases. In this case, there must not be any occurence of \input{variables} etc. before!

\input