def _execute_command(args):
"""Asserts that ``args.function`` is present and callable. Tries different
approaches to calling the function (with an `argparse.Namespace` object or
with ordinary signature). Yields the results line by line. If CommandError
is raised, its message is appended to the results (i.e. yielded by the
generator as a string). All other exceptions propagate unless marked as
wrappable by :func:`wrap_errors`.
"""
assert hasattr(args, 'function') and hasattr(args.function, '__call__')
# the function is nested to catch certain exceptions (see below)
def _call():
# Actually call the function
if getattr(args.function, ATTR_NO_NAMESPACE, False):
# filter the namespace variables so that only those expected by the
# actual function will pass
f = args.function
if hasattr(f, 'func_code'):
# Python 2
expected_args = f.func_code.co_varnames[:f.func_code.co_argcount]
else:
# Python 3
expected_args = f.__code__.co_varnames[:f.__code__.co_argcount]
ok_args = [x for x in args._get_args() if x in expected_args]
ok_kwargs = dict((k,v) for k,v in args._get_kwargs()
if k in expected_args)
result = args.function(*ok_args, **ok_kwargs)
else:
result = args.function(args)
# Yield the results
if isinstance(result, (GeneratorType, list, tuple)):
# yield each line ASAP, convert CommandError message to a line
for line in result:
yield line
else:
# yield non-empty non-iterable result as a single line
if result is not None:
yield result
wrappable_exceptions = [CommandError]
wrappable_exceptions += getattr(args.function, ATTR_WRAPPED_EXCEPTIONS, [])
try:
result = _call()
for line in result:
yield line
except tuple(wrappable_exceptions) as e:
yield text_type(e)
def _encode(line, output_file, encoding=None):
"""Converts given string to given encoding. If no encoding is specified, it
is determined from terminal settings or, if none, from system settings.
"""
# Convert string to Unicode
if not isinstance(line, text_type):
try:
line = text_type(line)
except UnicodeDecodeError:
line = b(line).decode('utf-8')
# Choose output encoding
if not encoding:
# choose between terminal's and system's preferred encodings
if output_file.isatty():
encoding = getattr(output_file, 'encoding', None)
encoding = encoding or locale.getpreferredencoding()
# Convert string from Unicode to the output encoding
return line.encode(encoding)
