python - 使用变量作为关键字分配关键字参数的大多数pythonic方式？

Question

解决以下问题的最pythonic 方法是什么？从交互式 shell:

>>> def f(a=False):
...     if a:
...         return 'a was True'
...     return 'a was False'
... 
>>> f(a=True)
'a was True'
>>> kw = 'a'
>>> val = True
>>> f(kw=val)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() got an unexpected keyword argument 'kw'

目前我用以下方法解决了这个问题:

>>> exec 'result = f(%s=val)' % kw
>>> result
'a was True'

但是看起来很笨拙...

(python 2.7+ 或 3.2+ 解决方案都可以)

Answer 1

使用keyword argument unpacking :

>>> kw = {'a': True}

>>> f(**kw)
<<< 'a was True'