Re: [PATCH] Python: discourage direct setup.py install

[Beraldo Leal]

On Mon, Feb 07, 2022 at 04:30:39PM -0500, John Snow wrote:
> When invoking setup.py directly, the default behavior for 'install' is
> to run the bdist_egg installation hook, which is ... actually deprecated
> by setuptools. It doesn't seem to work quite right anymore.
> 
> By contrast, 'pip install' will invoke the bdist_wheel hook
> instead. This leads to differences in behavior for the two approaches. I
> advocate using pip in the documentation in this directory, but the
> 'setup.py' which has been used for quite a long time in the Python world
> may deceptively appear to work at first glance.

+1 for that. Using setup.py directly is no longer a good practice. All
direct invocations of setup.py are deprecated.

> ---
>  python/setup.py | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/python/setup.py b/python/setup.py
> index 2014f81b75..c5bc45919a 100755
> --- a/python/setup.py
> +++ b/python/setup.py
> @@ -5,9 +5,26 @@
>  """
>  
>  import setuptools
> +from setuptools.command import bdist_egg
> +import sys
>  import pkg_resources
>  
>  
> +class bdist_egg_guard(bdist_egg.bdist_egg):
> +    """
> +    Protect against bdist_egg from being executed
> +
> +    This prevents calling 'setup.py install' directly, as the 'install'
> +    CLI option will invoke the deprecated bdist_egg hook. "pip install"
> +    calls the more modern bdist_wheel hook, which is what we want.
> +    """
> +    def run(self):
> +        sys.exit(
> +            'Installation directly via setup.py is not supported.\n'
> +            'Please use `pip install .` instead.'
> +        )
> +
> +
>  def main():
>      """
>      QEMU tooling installer
> @@ -16,7 +33,7 @@ def main():
>      # 
> https://medium.com/@daveshawley/safely-using-setup-cfg-for-metadata-1babbe54c108
>      pkg_resources.require('setuptools>=39.2')
>  
> -    setuptools.setup()
> +    setuptools.setup(cmdclass={'bdist_egg': bdist_egg_guard})
>  
>  

Reviewed-by: Beraldo Leal <bleal@redhat.com>

--
Beraldo