2018-04-16, 06:26
I recently started using Python decorators in my add-on, and I wanted to share some of the code snippets in case anyone else finds them useful. If you haven't used decorators yet, they're basically just functions with a special syntax that let you modify other functions by adding code before/after each call and also let you modify the function arguments.
The first decorator logs every call to a function, including the arguments and return values. The function call in the log also includes the module name, or just the class name if it's a method. If the return value is an iterable (like a list), it limits the log output to the first five values.
Example log output:
The other decorator forces all function arguments that are strings to be encoded as utf-8. I use this on all of my methods that query or update my SQLite database, and I haven't had any text encoding issues since.
These decorators have really helped clean up my code. I've been able to remove most of the basic log statements, and now text encoding doesn't clutter up my functions any more. In case you haven't used decorators in Python yet, here is how you would call them on a function:
The first decorator logs every call to a function, including the arguments and return values. The function call in the log also includes the module name, or just the class name if it's a method. If the return value is an iterable (like a list), it limits the log output to the first five values.
python:import xbmc
import xbmcaddon
addon = xbmcaddon.Addon()
STR_ADDON_NAME = addon.getAddonInfo('name')
STR_ADDON_VER = addon.getAddonInfo('version')
def log_msg(msg, loglevel=xbmc.LOGNOTICE):
''' log message with addon name and version to kodi log '''
if isinstance(msg, unicode):
msg = msg.encode('utf-8')
xbmc.log("{0} v{1} --> {2}".format(STR_ADDON_NAME, STR_ADDON_VER, msg), level=loglevel)
def log_decorator(func):
''' decorator for logging function call and return values '''
def wrapper(*args, **kwargs):
''' function wrapper '''
# call the function and get the return value
ret = func(*args, **kwargs)
# define the string for the function call (include class name for methods)
is_method = hasattr(args[0].__class__, func.__name__)
parent = args[0].__class__.__name__ if is_method \
else func.__module__.replace('resources.lib.', '')
func_str = '{0}.{1}'.format(parent, func.__name__)
# pretty formating for argument string
arg_list = list()
for arg in args[1 if is_method else 0:]:
arg_list.append("'{0}'".format(arg) if isinstance(arg, basestring) else str(arg))
for k, v in kwargs.iteritems():
arg_list.append('{0}={1}'\
.format(k, "'{0}'".format(v) if isinstance(v, basestring) else str(v)))
arg_str = '({0})'.format(', '.join(arg_list))
# add line breaks and limit output if ret value is iterable
try:
ret_list = ['\n'+str(x) for x in ret[:5]]
if len(ret) > 5:
ret_list += ['\n+{0} more items...'.format(len(ret)-5)]
ret_str = str().join(ret_list)
except TypeError:
ret_str = str(ret)
# log message at default loglevel
message = '{0}{1}: {2}'.format(func_str, arg_str, ret_str)
log_msg(message)
# return ret value from wrapper
return ret
return wrapper
Example log output:
Code:
20:40:54.848 T:123145517723648 NOTICE: Library Integration Tool v0.2.2 --> DB_Handler.update_content_status('plugin://plugin.video.crackle/?id=2537&mode=103&type=movies', 'staged'): None
20:40:54.849 T:123145517723648 NOTICE: Library Integration Tool v0.2.2 --> DB_Handler.get_content_items(status='managed', mediatype='movie'):
30 Minutes Or Less - plugin://plugin.video.crackle/?id=3133&mode=103&type=movies
6 Bullets - plugin://plugin.video.crackle/?id=2449&mode=103&type=movies
Airheads - plugin://plugin.video.crackle/?id=2975&mode=103&type=movies
American Crude - plugin://plugin.video.crackle/?id=1555&mode=103&type=movies
Angel of Death - plugin://plugin.video.crackle/?id=633&mode=103&type=movies
+119 more items...
20:41:01.586 T:123145517723648 NOTICE: Library Integration Tool v0.2.2 --> DB_Handler.get_content_items(status='staged', mediatype='movie'):
30 Days of Night: Dark Days - plugin://plugin.video.crackle/?id=2537&mode=103&type=movies
20:41:03.612 T:123145517723648 NOTICE: Library Integration Tool v0.2.2 --> DB_Handler.update_content_status('plugin://plugin.video.crackle/?id=2537&mode=103&type=movies', 'managed'): None
20:41:03.617 T:123145517723648 NOTICE: Library Integration Tool v0.2.2 --> utils.notification('All movies added'): None
20:41:06.587 T:123145517723648 NOTICE: Library Integration Tool v0.2.2 --> DB_Handler.get_all_shows('managed'):
Another Period
Broad City
Corporate
The Daily Show with Trevor Noah
Detroiters
+9 more items...
The other decorator forces all function arguments that are strings to be encoded as utf-8. I use this on all of my methods that query or update my SQLite database, and I haven't had any text encoding issues since.
python:def utf8_decorator(func):
''' decorator for encoding utf8 on all unicode arguments '''
def wrapper(*args, **kwargs):
''' function wrapper '''
new_args = (x.encode('utf-8') if isinstance(x, unicode) else x for x in args)
new_kwargs = {k: v.encode('utf-8') if isinstance(v, unicode) else v \
for k, v in kwargs.iteritems()}
return func(*new_args, **new_kwargs)
return wrapper
These decorators have really helped clean up my code. I've been able to remove most of the basic log statements, and now text encoding doesn't clutter up my functions any more. In case you haven't used decorators in Python yet, here is how you would call them on a function:
python:@utf8_decorator
@log_decorator
def add_synced_dir(self, label, path, mediatype):
''' Create an entry in Synced with specified values '''
self.c.execute(\
"INSERT OR IGNORE INTO Synced (Directory, Label, Type) VALUES (?, ?, ?)",\
(path, label, mediatype))
self.db.commit()
