zipline.utils.Sentinel - Code Metrics - Inspection of "MAINT: error message cleanup" - quantopian/zipline - Measure and Improve Code Quality continuously with Scrutinizer

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created 2015-11-24 22:06 UTC

zipline.utils.Sentinel A

↳ Parent: zipline.utils.sentinel()

Complexity

Total Complexity

Size/Duplication

Total Lines	20
Duplicated Lines	0 %

Metric	Value
dl	0
loc	20
rs	10
wmc	5

"""
Construction of sentinel objects.

Sentinel objects are used when you only care to check for object identity.
"""
import sys
from textwrap import dedent


def sentinel(name, doc=None):
    try:
        value = sentinel._cache[name]  # memoized
    except KeyError:
        pass
    else:
        if doc == value.__doc__:
            return value

        raise ValueError(dedent(
            """\
            New sentinel value %r conflicts with an existing sentinel of the
            same name.
            Old sentinel docstring: %r
            New sentinel docstring: %r
            Resolve this conflict by changing the name of one of the sentinels.
            """,
        ) % (name, value.__doc__, doc))

    @object.__new__   # bind a single instance to the name 'Sentinel'
    class Sentinel(object):
        __doc__ = doc
        __slots__ = ('__weakref__',)
        __name__ = name

        def __new__(cls):
            raise TypeError('cannot create %r instances' % name)

        def __repr__(self):
            return 'sentinel(%r)' % name

        def __reduce__(self):
            return sentinel, (name, doc)

        def __deepcopy__(self, _memo):
            return self

        def __copy__(self):
            return self

    cls = type(Sentinel)
    try:
        # traverse up one frame to find the module where this is defined
        cls.__module__ = sys._getframe(1).f_globals['__name__']
    except (ValueError, KeyError):
        # Couldn't get the name from the calling scope, just use None.
        cls.__module__ = None

    sentinel._cache[name] = Sentinel  # cache result
    return Sentinel
sentinel._cache = {}


1			"""
2			Construction of sentinel objects.
3
4			Sentinel objects are used when you only care to check for object identity.
5			"""
6			import sys
7			from textwrap import dedent
8
9
10			def sentinel(name, doc=None):
11			try:
12			value = sentinel._cache[name] # memoized
13			except KeyError:
14			pass
15			else:
16			if doc == value.__doc__:
17			return value
18
19			raise ValueError(dedent(
20			"""\
21			New sentinel value %r conflicts with an existing sentinel of the
22			same name.
23			Old sentinel docstring: %r
24			New sentinel docstring: %r
25			Resolve this conflict by changing the name of one of the sentinels.
26			""",
27			) % (name, value.__doc__, doc))
28
29			@object.__new__ # bind a single instance to the name 'Sentinel'
30			class Sentinel(object):
31			__doc__ = doc
32			__slots__ = ('__weakref__',)
33			__name__ = name
34
35			def __new__(cls):
36			raise TypeError('cannot create %r instances' % name)
37
38			def __repr__(self):
39			return 'sentinel(%r)' % name
40
41			def __reduce__(self):
42			return sentinel, (name, doc)
43
44			def __deepcopy__(self, _memo):
45			return self
46
47			def __copy__(self):
48			return self
49
50			cls = type(Sentinel)
51			try:
52			# traverse up one frame to find the module where this is defined
53			cls.__module__ = sys._getframe(1).f_globals['__name__']
54			except (ValueError, KeyError):
55			# Couldn't get the name from the calling scope, just use None.
56			cls.__module__ = None
57
58			sentinel._cache[name] = Sentinel # cache result
59			return Sentinel
60			sentinel._cache = {}
61

quantopian / zipline

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zipline.utils.Sentinel A

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