Brew updates installed formulaes

Hi all,

I kind of new to brew and there’s a simple thing I can’t get.

When I try to install python with brew install python, I got an error that python is already installed:

Error: python@3.8 3.6.5 is already installed
To upgrade to 3.8.5, run `brew upgrade python@3.8`.

Ok, we can’t have two versions of the same formulae installed.

But when I install some formulae, that depends on python, e.g. graphviz, brew updates
python to the last version, so I have python 3.8.5 installed.

The questions are: if the observed behavior is an expected one? and if it is, can someone
provide a reference to the documentation where it’s described?

Thanks!

Homebrew will always make sure your dependencies are fulfilled. That’s not documented anywhere, it’s just a basic feature of a package manager. If you revert a dependency to an earlier version homebrew will overwrite that to fulfill it’s tasks.

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