"""ESC/POS configuration manager.
This module contains the implementations of abstract base class :py:class:`Config`.
"""
import os
import appdirs
import yaml
from . import exceptions, printer
[docs]
class Config(object):
"""Configuration handler class.
This class loads configuration from a default or specified directory. It
can create your defined printer and return it to you.
"""
_app_name = "python-escpos"
_config_file = "config.yaml"
def __init__(self):
"""Initialize configuration.
Remember to add anything that needs to be reset between configurations
to self._reset_config
"""
self._has_loaded = False
self._printer = None
self._printer_name = None
self._printer_config = None
def _reset_config(self):
"""Clear the loaded configuration.
If we are loading a changed config, we don't want to have leftover
data.
"""
self._has_loaded = False
self._printer = None
self._printer_name = None
self._printer_config = None
[docs]
def load(self, config_path=None):
"""Load and parse the configuration file using pyyaml.
:param config_path: An optional file path, file handle, or byte string
for the configuration file.
"""
self._reset_config()
if not config_path:
config_path = os.path.join(
appdirs.user_config_dir(self._app_name), self._config_file
)
try:
# First check if it's file like. If it is, pyyaml can load it.
# I'm checking type instead of catching exceptions to keep the
# exception handling simple
if hasattr(config_path, "read"):
config = yaml.safe_load(config_path)
else:
# If it isn't, it's a path. We have to open it first, otherwise
# pyyaml will try to read it as yaml
with open(config_path, "rb") as config_file:
config = yaml.safe_load(config_file)
except EnvironmentError:
raise exceptions.ConfigNotFoundError(
"Couldn't read config at {config_path}".format(
config_path=str(config_path),
)
)
except yaml.YAMLError:
raise exceptions.ConfigSyntaxError("Error parsing YAML")
if "printer" in config:
self._printer_config = config["printer"]
self._printer_name = self._printer_config.pop("type").title()
if not self._printer_name or not hasattr(printer, self._printer_name):
raise exceptions.ConfigSyntaxError(
'Printer type "{printer_name}" is invalid'.format(
printer_name=self._printer_name,
)
)
self._has_loaded = True
[docs]
def printer(self):
"""Return a printer that was defined in the config.
Throw an exception on error.
This method loads the default config if one has not been already loaded.
"""
if not self._has_loaded:
self.load()
if not self._printer_name:
raise exceptions.ConfigSectionMissingError("printer")
if not self._printer:
# We could catch init errors and make them a ConfigSyntaxError,
# but I'll just let them pass
self._printer = getattr(printer, self._printer_name)(**self._printer_config)
return self._printer