Environment Wrangling

enving.py

import os
import sys
from copy import deepcopy

platform = sys.platform.rstrip('1234567890').lower()
if platform == 'darwin':
    platform = 'osx'
elif platform == 'linux':
    platform = 'unix'


env_a = {
    'PATH': ['New/Path/A', 'New/Path/B'],
    'PYTHONPATH': ['Another/Path/A', 'B', '$STRVARB'],
    'STRVAR': 'STRVAR',
    'NUMVAR': 890176,
    'PLATVAR': {
        'win': 'windowses',
        'osx': 'osxes',
        'unix': 'unixes',
    }
}


env_b = {
    'PATH': ['New/Path/A', 'New/Path/B', 'New/Path/C'],
    'PYTHONPATH': ['Another/Path/A', 'B', 'C'],
    'STRVARB': '$STRVAR',
    'NUMVAR': 89017,
    'PLATVARB': {
        'win': 'windowsesb',
        'osx': 'osxesb',
        'unix': 'unixesb',
    }
}


def join_envs(*envs):
    out_env = {}

    for env in envs:
        for k, v in env.iteritems():
            if isinstance(v, dict):
                out_env[k] = v[platform]
            elif isinstance(v, (int, float, long)):
                out_env[k] = str(v)
            elif isinstance(v, basestring):
                out_env[k] = v
            elif isinstance(v, unicode):
                out_env[k] = str(v)
            elif isinstance(v, (list, tuple, set)):
                if not k in out_env:
                    out_env[k] = list(v)
                elif isinstance(out_env[k], list):
                    for item in v:
                        if not item in out_env[k]:
                            out_env[k].insert(0, item)
                elif isinstance(out_env[k], basestring):
                    v.append(out_env[k])
                    out_env[k] = v
            else:
                raise TypeError('{} not a valid value type'.format(type(v)))

    return out_env


def env_to_dict(env, pathsep=os.pathsep):
    out_dict = {}

    for k, v in env.iteritems():
        if pathsep in v:
            out_dict[k] = v.split(pathsep)
        else:
            out_dict[k] = v

    return out_dict


def dict_to_env(env, pathsep=os.pathsep):
    out_env = {}

    for k, v in env.iteritems():
        if isinstance(v, list):
            out_env[k] = pathsep.join(v)
        elif isinstance(v, basestring):
            out_env[k] = v
        else:
            raise TypeError('{} not a valid env var type'.format(type(v)))

    return out_env


def expand_env(env, using=None):

    using = using or os.environ.data
    default_env = deepcopy(os.environ.data)
    os.environ.data = using

    out_env = {}

    # Expand
    for k, v in env.iteritems():
        out_env[k] = os.path.expandvars(v)

    # Again for nested variable references
    for k, v in out_env.items():
        out_env[k] = os.path.expandvars(v)

    os.environ.data = default_env
    return out_env

env_c = join_envs(env_to_dict(os.environ.data), env_a, env_b)
env_d = dict_to_env(env_c)


import pprint
pprint.pprint(env_c)
pprint.pprint(env_d)

os.environ.data = expand_env(env_d, env_d)
pprint.pprint(os.environ.data)