1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
|
==============
async_property
==============
.. image:: https://img.shields.io/pypi/v/async_property.svg
:target: https://pypi.org/project/async-property/
.. image:: https://app.travis-ci.com/ryananguiano/async_property.svg?branch=master
:target: https://app.travis-ci.com/github/ryananguiano/async_property
.. image:: https://readthedocs.org/projects/async-property/badge/?version=latest
:target: https://async-property.readthedocs.io/en/latest/?badge=latest
:alt: Documentation Status
.. image:: https://pyup.io/repos/github/ryananguiano/async_property/shield.svg
:target: https://pyup.io/repos/github/ryananguiano/async_property/
:alt: Updates
Python decorator for async properties.
* Python: 3.7+
* Free software: MIT license
* Documentation: https://async-property.readthedocs.io
* Package: https://pypi.org/project/async-property
* Source code: https://github.com/ryananguiano/async_property
Install
-------
To install async_property, run this command in your terminal:
.. code-block:: console
$ pip install async-property
Or if you have pipenv:
.. code-block:: console
$ pipenv install async-property
Usage
-----
You can use ``@async_property`` just as you would with ``@property``, but on an async function.
.. code-block:: python
class Foo:
@async_property
async def remote_value(self):
return await get_remote_value()
The property ``remote_value`` now returns an awaitable coroutine.
.. code-block:: python
instance = Foo()
await instance.remote_value
Cached Properties
~~~~~~~~~~~~~~~~~
``@async_cached_property`` will call the function only once. Subsequent awaits to the property will return a cached value.
.. code-block:: python
class Foo:
@async_cached_property
async def value(self):
print('loading value')
return 123
>>> instance = Foo()
>>> instance.value
<AwaitableOnly "Foo.value">
>>> await instance.value
loading value
123
>>> await instance.value
123
>>> instance.value
123
>>> instance.value = 'abc'
>>> instance.value
'abc'
>>> await instance.value
'abc'
>>> del instance.value
>>> await instance.value
loading value
123
AwaitLoader
~~~~~~~~~~~
If you have an object with multiple cached properties, you can subclass ``AwaitLoader``. This will make your class instances awaitable and will load all ``@async_cached_property`` fields concurrently. ``AwaitLoader`` will call ``await instance.load()``, if it exists, before loading properties.
.. code-block:: python
class Foo(AwaitLoader):
async def load(self):
print('load called')
@async_cached_property
async def db_lookup(self):
return 'success'
@async_cached_property
async def api_call(self):
print('calling api')
return 'works every time'
>>> instance = await Foo()
load called
calling api
>>> instance.db_lookup
'success'
>>> instance.api_call
'works every time'
Features
--------
* Both regular and cached property.
* Cached properties can be accessed multiple times without repeating function call.
* Uses asyncio.Lock to ensure cached functions are called only once.
* Full test coverage with py.test
Credits
-------
This package was created with Cookiecutter_ and the `audreyr/cookiecutter-pypackage`_ project template.
.. _Cookiecutter: https://github.com/audreyr/cookiecutter
.. _`audreyr/cookiecutter-pypackage`: https://github.com/audreyr/cookiecutter-pypackage
The ObjectProxy_ class was taken from wrapt_ library by Graham Dumpleton.
.. _ObjectProxy: https://github.com/GrahamDumpleton/wrapt/blob/master/src/wrapt/wrappers.py
.. _wrapt: https://github.com/GrahamDumpleton/wrapt
|
