site_init.py

"""
Decorate SCons Environment constructor so that Homebrew paths are always included.
"""

from functools import wraps
import SCons.Environment

# Homebrew install directory
homebrew = '/opt/homebrew'

flag_prepends = [
    ('CFLAGS',   '-I{}/include'.format(homebrew)),
    ('CXXFLAGS', '-I{}/include'.format(homebrew)),
    ('LDFLAGS',  '-L{}/lib'    .format(homebrew)),
]

def add_homebrew_vars(environment_init):
    @wraps(environment_init)
    def wrapper(self, *args, **kwargs):
        for var, flag in flag_prepends:
            flags_list = [flag]
            if var in kwargs:
                flags_list.append(kwargs[var])
            kwargs[var] = ' '.join(flags_list)

        environment_init(self, *args, **kwargs)

        self.PrependENVPath('PATH', '{}/bin'.format(homebrew))

    return wrapper

SCons.Environment.Environment.__init__ = add_homebrew_vars(SCons.Environment.Environment.__init__)