Stuff that comes with macOS or libraries that are provided by RubyGems, CPAN or PyPi should not be duplicated. There are good reasons for this:
There are exceptions:
|ruby, python, perl||People want newer versions|
|bash||macOS’s bash is stuck at 3.2 because newer versions are licensed under GPLv3|
|zsh||This was a mistake, but it’s too late to remove it|
|emacs, vim||Too popular to move to dupes|
|subversion||Originally added for 10.5, but people want the latest version|
|libcurl||Some formulae require a newer version than macOS provides|
|openssl||macOS’s openssl is deprecated & outdated|
|libxml2||Historically, macOS’s libxml2 has been buggy|
We also maintain a tap that contains many duplicates not otherwise found in Homebrew.
Software that can upgrade itself does not integrate well with Homebrew’s own upgrade functionality.
Because that circumvents our hash-checks, makes finding/fixing bugs harder, often breaks patches and disables the caching. Almost always you can add a resource to the formula file to handle the separate download and then the installer script will not attempt to load that stuff on demand. Or there is a command-line switch where you can point it to the downloaded archive in order to avoid loading.
Our policy is that formulae in the core tap (homebrew/core) must be open-source and either built from source or produce cross-platform binaries (e.g. Java). Binary-only formulae should go to Homebrew Cask.
Formulae in the core repository must have a stable version tagged by the upstream project. Tarballs are preferred to Git checkouts, and tarballs should include the version in the filename whenever possible.
We don’t accept software without a tagged version because they regularly break due to upstream changes and we can’t provide bottles for them.
If not, then put bindings in the formula they bind to. This is more useful to people. Just install the stuff! Having to faff around with foo-ruby, foo-perl etc. sucks.
The software in question must be:
We will reject formulae that seem too obscure, partly because they won’t get maintained and partly because we have to draw the line somewhere.
We frown on authors submitting their own work unless it is very popular.
Don’t forget Homebrew is all Git underneath! Maintain your own tap if you have to!
There may be exceptions to these rules in the main repository; we may include things that don’t meet these criteria or reject things that do. Please trust that we need to use our discretion based on our experience running a package manager.
Don’t make your formula build an
.app (native macOS Application); we
don’t want those things in Homebrew (but
Homebrew Cask does).
Make it build a command-line tool or a library.
Even if all criteria are met we may not accept the formula. Documentation tends to lag behind current decision-making. Although some rejections may seem arbitrary or strange they are based on years of experience making Homebrew work acceptably for our users.