Pretending a package has been loaded

Question

I am trying to use imakeidx and the regexpatch package in the same class. Since imakeidx depends on the xpatch package and xpatch provides the same commands (same names, improved implementation) as regexpatch this gives errors (redefining commands). Is there anyway to pretend I loaded the xpatch package, so the require inside imakeidx won"t load anything? (Since I load regexpatch before, everything should be fine).

While I have a concrete example above, I would be interested in the general answer to prevent require statements from loading packages, a workaround for my particular case is a bonus (I guess either I am doing something wrong or the package author will take a look).

Answer 1

One can use David's suggestion, but etoolbox must be loaded anyway:

\ProvidesFile{xpatch.sty}
\usepackage{etoolbox}
\usepackage{imakeidx}
\usepackage{regexpatch}

should do.

Answer 2

egreg answered the specific issue but the general issue of avoiding package loading as mentioned in comments:

\documentclass{article}

\ProvidesFile{longtable.sty}

\usepackage{longtable}

\typeout{longtable is: \meaning\longtable}

\stop

produces

longtable is: undefined

showing that the package is not loaded, despite the \usepackage.