Completed
Pull Request — master (#890)
by Warren
01:23
created

zipline.utils.wrapped()   A

Complexity

Conditions 1

Size

Total Lines 4

Duplication

Lines 0
Ratio 0 %
Metric Value
cc 1
dl 0
loc 4
rs 10
1
#
2
# Copyright 2014 Quantopian, Inc.
3
#
4
# Licensed under the Apache License, Version 2.0 (the "License");
5
# you may not use this file except in compliance with the License.
6
# You may obtain a copy of the License at
7
#
8
#     http://www.apache.org/licenses/LICENSE-2.0
9
#
10
# Unless required by applicable law or agreed to in writing, software
11
# distributed under the License is distributed on an "AS IS" BASIS,
12
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13
# See the License for the specific language governing permissions and
14
# limitations under the License.
15
16
from functools import wraps
17
18
import zipline.api
19
from zipline.utils.algo_instance import get_algo_instance, set_algo_instance
20
21
22
class ZiplineAPI(object):
23
    """
24
    Context manager for making an algorithm instance available to zipline API
25
    functions within a scoped block.
26
    """
27
28
    def __init__(self, algo_instance):
29
        self.algo_instance = algo_instance
30
31
    def __enter__(self):
32
        """
33
        Set the given algo instance, storing any previously-existing instance.
34
        """
35
        self.old_algo_instance = get_algo_instance()
36
        set_algo_instance(self.algo_instance)
37
38
    def __exit__(self, _type, _value, _tb):
39
        """
40
        Restore the algo instance stored in __enter__.
41
        """
42
        set_algo_instance(self.old_algo_instance)
43
44
45
def api_method(f):
46
    # Decorator that adds the decorated class method as a callable
47
    # function (wrapped) to zipline.api
48
    @wraps(f)
49
    def wrapped(*args, **kwargs):
50
        # Get the instance and call the method
51
        return getattr(get_algo_instance(), f.__name__)(*args, **kwargs)
52
    # Add functor to zipline.api
53
    setattr(zipline.api, f.__name__, wrapped)
54
    zipline.api.__all__.append(f.__name__)
55
    f.is_api_method = True
56
    return f
57
58
59
def require_not_initialized(exception):
60
    """
61
    Decorator for API methods that should only be called during or before
62
    TradingAlgorithm.initialize.  `exception` will be raised if the method is
63
    called after initialize.
64
65
    Usage
66
    -----
67
    @require_not_initialized(SomeException("Don't do that!"))
68
    def method(self):
69
        # Do stuff that should only be allowed during initialize.
70
    """
71
    def decorator(method):
72
        @wraps(method)
73
        def wrapped_method(self, *args, **kwargs):
74
            if self.initialized:
75
                raise exception
76
            return method(self, *args, **kwargs)
77
        return wrapped_method
78
    return decorator
79
80
81
def require_initialized(exception):
82
    """
83
    Decorator for API methods that should only be called after
84
    TradingAlgorithm.initialize.  `exception` will be raised if the method is
85
    called before initialize has completed.
86
87
    Usage
88
    -----
89
    @require_initialized(SomeException("Don't do that!"))
90
    def method(self):
91
        # Do stuff that should only be allowed after initialize.
92
    """
93
    def decorator(method):
94
        @wraps(method)
95
        def wrapped_method(self, *args, **kwargs):
96
            if not self.initialized:
97
                raise exception
98
            return method(self, *args, **kwargs)
99
        return wrapped_method
100
    return decorator
101