Is it possible to disable build_ext for develop/editable installation?

[senysenyseny16]

hi!

Most of the python source files (*.py) are compiled into *.so for "production" wheel, but for development it is necessary to keep them as source files.

I tried to implement SubCommand protocol for build_ext command with self.editable_mode in run, initialize/finalize_options methods, something like:

if self.editable_mode:
    return

But when I type pip install -vvv -e ., initialize/finalize options methods of build_ext command are triggered many times and only in the last call self.editable_mode is True:

1. Running command Getting requirements to build editable | (cython here)
2. Running command Preparing editable metadata (pyproject.toml) | (cython here)
3. Running command Building editable for <package-name> (pyproject.toml) | (cython x2)

So, I have a lot of extra work and unwanted artifacts in the source directory.

How can i solve this problem?
Thanks in advance.

[abravalheri]

Have you considered postponing some of the processing you are doing to the run method?

In theory the initialize/finalize_options methods should not generate artifacts or modify the file system, only the run file is assumed to do that.

The if self.editable_mode trick should work for run, but there is no guarantees in initialize/finalize_options.

[senysenyseny16]

Hi @abravalheri, thanks for your reply.

In simplified case I need two behavior:

• "production": all *.py files should be compiled into *.so with the help of Cython (*.py -> *.c -> *.so)
• editable: nothing to compile, no build_ext/ext_modules

To make "production" wheel I know two ways, the first of them:

setup(
    ext_modules = cythonize("package/*.py")
)

In this case Cython will compile extensions for any installation (prod and editable).

The second: extend build_ext command from Cython package, but it intensively uses initialize/finalize options.

[abravalheri]

If you have a look on the source-code, you can see that both setuptools.command.build_ext:build_ext and Cython.Distutils.build_ext:build_ext don't create any files in initialize/finalize_options, they just modify attributes.

They will only touch the disk when the run method is called. With that in mind, it would still be possible to customise the run method behaviour based on if self.editable_mode...

So maybe the extra artifacts that you don't want are generated elsewhere?

How about the cythonize function you are calling in setup.py. Are you sure is not this function that changes the file system?

---

In this case Cython will compile extensions for any installation (prod and editable).

Have you tried extending build_ext and using if self.editable_mode inside def run to avoid the compilation, what is the outcome?

Please remember to set self.editable_mode = False inside initialize_options so the attribute is defined. This will allow setuptools to automatically modify it later.

[senysenyseny16]

Thank you @abravalheri. Problem solved.

[Vegal56]

Thanks for solution
!!!