redefine – Conditional macro, etc., definitions
Defines commands \newdef, \newgdef and \newlet that warn the user if a command is redefined using them (if operating under LaTeX, \newcommand is similarly modified). In addition \newif, \newbox, \newcount, \newdimen, \newtoks are modified to detect an error if a conditional or register name is reused.
Maybe you are interested in the following packages as well.
- extradefs: A miscellany of support macros
- bibplain: Simple macros for using BibTeX with Plain TeX
- miniltx: An abstract of LaTeX facilities for use with Plain TeX
- patch: Patch loaded packages, etc