| commit | author | age | ||
| fc47a4 | 1 | from functools import update_wrapper |
| 462af2 | 2 | |
| TS | 3 | |
| 5babba | 4 | class reify(object): |
| 07cb8f | 5 | """ Use as a class method decorator. It operates almost exactly like the |
| CM | 6 | Python ``@property`` decorator, but it puts the result of the method it |
| 7 | decorates into the instance dict after the first call, effectively | |
| 8 | replacing the function it decorates with an instance variable. It is, in | |
| 206197 | 9 | Python parlance, a non-data descriptor. The following is an example and |
| SP | 10 | its usage: |
| 07cb8f | 11 | |
| b5fcc4 | 12 | .. doctest:: |
| SP | 13 | |
| 206197 | 14 | >>> from pyramid.decorator import reify |
| SP | 15 | |
| 16 | >>> class Foo(object): | |
| 17 | ... @reify | |
| 18 | ... def jammy(self): | |
| 19 | ... print('jammy called') | |
| 20 | ... return 1 | |
| 21 | ||
| b5fcc4 | 22 | >>> f = Foo() |
| SP | 23 | >>> v = f.jammy |
| 24 | jammy called | |
| 25 | >>> print(v) | |
| 26 | 1 | |
| 27 | >>> f.jammy | |
| 28 | 1 | |
| 29 | >>> # jammy func not called the second time; it replaced itself with 1 | |
| 30 | >>> # Note: reassignment is possible | |
| 31 | >>> f.jammy = 2 | |
| 32 | >>> f.jammy | |
| 33 | 2 | |
| 07cb8f | 34 | """ |
| 0c29cf | 35 | |
| 5babba | 36 | def __init__(self, wrapped): |
| CM | 37 | self.wrapped = wrapped |
| fc47a4 | 38 | update_wrapper(self, wrapped) |
| 5babba | 39 | |
| CM | 40 | def __get__(self, inst, objtype=None): |
| 41 | if inst is None: | |
| 42 | return self | |
| 43 | val = self.wrapped(inst) | |
| 44 | setattr(inst, self.wrapped.__name__, val) | |
| 45 | return val | |
