```{index} single: install; re function ``` ```{index} single: re::install; Perl function ``` # install Return an integer handle to the regex engine and reset the debug-colour flag. Not intended for user code. This is the hook `use re` itself calls to wire the debug engine into `%^H{regcomp}`. End users should write `use re 'debug'`, `use re 'eval'`, `use re '/ix'` and friends instead of touching `install` directly. ## Synopsis ```perl my $handle = re::install(); # pragma plumbing; not for application code ``` ## What you get back An integer that, when reinterpreted as a C pointer, resolves to the compile-time regex engine. Any other use of the value produces undefined behaviour. ## Differences from upstream - The returned integer points to the core regex engine, not to the debug engine. The debug engine is not available in this build; `use re 'debug'` therefore cannot produce upstream-style compile-time dumps. Truthiness of the return value — which is all the non-debug subpragmas (`taint`, `eval`) rely on — is preserved.