MIME-Version: 1.0
References: 
 <CACfSeTE=r0BkTB8S_1BDw8=5tharqoZAaeRLUNkYPsSu8jbw+A@mail.gmail.com>
In-Reply-To: 
 <CACfSeTE=r0BkTB8S_1BDw8=5tharqoZAaeRLUNkYPsSu8jbw+A@mail.gmail.com>
From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Tue, 23 May 2023 13:18:17 +0200
Message-ID: 
 <CA+mi_8Yxu1845mO5BBTVX3jsYEJqZ8QHWPrSPFDerKoQU2pu1g@mail.gmail.com>
Subject: Re: Does psycopg2-binary provide the psycopg2 package?
To: Kerrick Staley <kstaley@janestreet.com>
Cc: psycopg@postgresql.org
Content-Type: text/plain; charset="UTF-8"
Archived-At: 
 <https://www.postgresql.org/message-id/CA%2Bmi_8Yxu1845mO5BBTVX3jsYEJqZ8QHWPrSPFDerKoQU2pu1g%40mail.gmail.com>
Precedence: bulk

On Tue, 23 May 2023 at 08:52, Kerrick Staley <kstaley@janestreet.com> wrote:
>
> If I install psycopg2-binary, and then I try to install a package that depends on psycopg2, will pip "know" that psycopg2-binary satisfies the psycopg2 requirement and avoid installing psycopg2?
>
> Empirically the answer seems to be "no". I installed psycopg2-binary, then ran `python3 -m pip install -e .` in a directory with this setup.py file, and it tried to install psycopg2.
>
> Is there a way that, in my setup.py file, I can depend on either psycopg2 or psycopg2-binary, whichever is available?

I don't think there is. You cannot make a package depending on either
one or the other. Python packaging metadata doesn't offer this
flexibility.

In psycopg 3 the only package to depend on is `psycopg`. The
pre-compiled C module (the `psycopg-binary` package on pypi) can be
added as an add-on and it is not necessary for a library to depend on
it. It can be an application requirement instead.

In my projects I use `psycopg` as an abstract dependency (in the
`setup.cfg` of the packages that need psycopg) and
`psycopg-binary==3.x.x` as a concrete dependency (in a
`requirements.txt` file generated by `pip-tools` using `psycopg-binary
in the `requirements.in`)

More details about psycopg 3 versions management are available at
https://www.psycopg.org/psycopg3/docs/basic/install.html#handling-dependencies

-- Daniele