Re: How to get the source code of python function being decorated?

[Peter Otten]

Peng Yu wrote:

> Hi, See the following example, I am not able to get the source code of
> the actual function that does the calculation of partial_ratio. Does
> anybody know what is the correct way of getting the source?
> 
> /tmp$ ./main.py
> @functools.wraps(func)
> def decorator(*args, **kwargs):
> if args[0] is None or args[1] is None:
> return 0
> return func(*args, **kwargs)
> 
> /tmp$ cat ./main.py
> #!/usr/bin/env python
> # vim: set noexpandtab tabstop=2 shiftwidth=2 softtabstop=-1
> # fileencoding=utf-8:
> 
> import fuzzywuzzy.fuzz
> import inspect
> print inspect.getsource(fuzzywuzzy.fuzz.partial_ratio)

In Python 3 functools.wraps() records the wrapped function as __wrapped__:

$ cat tmp.py
import functools

def spam(func):
@functools.wraps(func)
def decorator(*args, **kwargs):
return func(*args, **kwargs)
return decorator

@spam
def ham(foo, bar):
return 42

$ python3
...
>>> import inspect
>>> import tmp  
>>> print(inspect.getsource(tmp.ham))
@functools.wraps(func)
def decorator(*args, **kwargs):
return func(*args, **kwargs)

>>> print(inspect.getsource(tmp.ham.__wrapped__))
@spam
def ham(foo, bar):
return 42

In Python 2 when you look into the attributes of tmp.ham() using dir() 
you'll eventually find

>>> print inspect.getsource(tmp.ham.__closure__[0].cell_contents)
@spam
def ham(foo, bar):
return 42

but I'm not sure this is general enough to spare you the look into the 
source code.

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Re: How to get the source code of python function being decorated?

[Ned Batchelder]

On Friday, September 16, 2016 at 3:20:15 PM UTC-4, Peng Yu wrote:
> Hi, See the following example, I am not able to get the source code of
> the actual function that does the calculation of partial_ratio. Does
> anybody know what is the correct way of getting the source?
> 
> /tmp$ ./main.py
> @functools.wraps(func)
> def decorator(*args, **kwargs):
> if args[0] is None or args[1] is None:
> return 0
> return func(*args, **kwargs)
> 
> /tmp$ cat ./main.py
> #!/usr/bin/env python
> # vim: set noexpandtab tabstop=2 shiftwidth=2 softtabstop=-1 
> fileencoding=utf-8:
> 
> import fuzzywuzzy.fuzz
> import inspect
> print inspect.getsource(fuzzywuzzy.fuzz.partial_ratio)
>

In general, you can't get at the decorated function. Decorators can
do anything they want with the function they decorate, including
completely ignore it, or store it in a closure, assign it to a global,
add it to a data structure, etc.

Can you tell us more about the problem you are trying to solve? Why
do you want a program that access the source of decorated functions?
Maybe there's another way to get at what you need.

--Ned.
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How to get the source code of python function being decorated?

[Peng Yu]

Hi, See the following example, I am not able to get the source code of
the actual function that does the calculation of partial_ratio. Does
anybody know what is the correct way of getting the source?

/tmp$ ./main.py
@functools.wraps(func)
def decorator(*args, **kwargs):
if args[0] is None or args[1] is None:
return 0
return func(*args, **kwargs)

/tmp$ cat ./main.py
#!/usr/bin/env python
# vim: set noexpandtab tabstop=2 shiftwidth=2 softtabstop=-1 fileencoding=utf-8:

import fuzzywuzzy.fuzz
import inspect
print inspect.getsource(fuzzywuzzy.fuzz.partial_ratio)

-- 
Regards,
Peng
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