python-tools/voidpp_tools/config_loader.py at master · voidpp/python-tools · GitHub

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import os

import abc

from .dict_utils import recursive_update

class ConfigLoaderException(Exception):

pass

class ConfigFileNotFoundException(Exception):

pass

class ConfigFormatter(object):

__metaclass__ = abc.ABCMeta

@abc.abstractmethod

def encode(self, data):

"""

Args:

data: any serializable python type

Returns:

The encoded string data

"""

pass

@abc.abstractmethod

def decode(self, data):

"""

Args:

data (str): the raw data from the file

Returns:

Dict, list or any serializable python type

"""

pass

class ConfigLoader(object):

"""

Args:

formatter (ConfigFormatter): config encode/decode interface instance

base_path (str): a custom path which may be contains the config

nested (bool): in case of true, load all the config files found in the sources and merges it

"""

def __init__(self, formatter, base_path, nested = False):

self.sources = [

os.getcwd(),

os.path.dirname(os.path.abspath(base_path)),

os.path.expanduser('~'),

'/etc',

]

self.__loaded_config_file = None

self.__formatter = formatter

self.__nested = nested

@property

def filename(self):

return self.__loaded_config_file

def __search_config_files(self, filename):

filenames = []

tries = []

for source in self.sources:

file_path = os.path.join(source, filename)

tries.append(file_path)

if not os.path.exists(file_path):

continue

filenames.append(file_path)

return filenames, tries

def __load_config_files(self, filenames):

data = dict()

for filename in filenames:

with open(filename) as f:

recursive_update(data, self.__formatter.decode(f.read()))

return data

def load(self, filename, create = None, default_conf = {}):

"""Load the config file

Args:

filename (str): the filename of the config, without any path

create (str): if the config file not found, and this parameter is not None,

a config file will be create with content of default_conf

default_conf (dict): content of the default config data

Returns:

Return value of the ConfigFormatter.decode or the default_conf value

Raises:

ConfigFileNotFoundException: if the config file not found

"""

filenames, tries = self.__search_config_files(filename)

if len(filenames):

self.__loaded_config_file = filenames if self.__nested else filenames[0]

return self.__load_config_files(filenames if self.__nested else filenames[:1])

if create is not None:

self.__loaded_config_file = os.path.join(create, filename)

self.save(default_conf)

return default_conf

raise ConfigFileNotFoundException("Config file not found in: %s" % tries)

def save(self, data):

"""Save the config data

Args:

data: any serializable config data

Raises:

ConfigLoaderException: if the ConfigLoader.load not called, so there is no config file name,

or the data is not serializable or the loader is nested

"""

if self.__nested:

raise ConfigLoaderException("Cannot save the config if the 'nested' paramter is True!")

if self.__loaded_config_file is None:

raise ConfigLoaderException("Load not called yet!")

try:

with open(self.__loaded_config_file, 'w') as f:

f.write(self.__formatter.encode(data))

except Exception as e:

raise ConfigLoaderException("Config data is not serializable: %s" % e)

python-tools/voidpp_tools/config_loader.py at master · voidpp/python-tools · GitHub

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