pass build_ext options to pip install

Question

Is there some way to pass build_ext options to pip install to alter how an extension included in a package is compiled? (Yes, I know that one can download the source and build/install with a custom setup.cfg, but I'm curious whether it is possible to pass options that can be specified in setup.cfg directly through pip.)

Answer 1

It's possible using pip --global-option=build_ext.

For example this is requirements.txt for Pillow with PNG and JPEG support and no other external libraries:

pillow \         --global-option="build_ext" \         --global-option="--enable-zlib" \         --global-option="--enable-jpeg" \         --global-option="--disable-tiff" \         --global-option="--disable-freetype" \         --global-option="--disable-tcl" \         --global-option="--disable-tk" \          --global-option="--disable-lcms" \         --global-option="--disable-webp" \         --global-option="--disable-webpmux" \         --global-option="--disable-jpeg2000" 

This is really an abuse of pip --global-option, inspired by this answer, as build_ext is a pip command and not really a global pip option. But this would make pip to execute two commands — first build_ext and then install — like this:

pip \     build_ext \         --enable-zlib --enable-jpeg \         --disable-tiff --disable-freetype --disable-tcl --disable-tk \         --disable-lcms --disable-webp --disable-webpmux --disable-jpeg2000 \     install pillow