[Python] close or not close file descriptor in a function body?

I found many many times a code like this

def content(path):
return open(path).read()


I have met such construct typically by programmers coming from lower level languages such as C or C++.

More conventional constructs are instead the following:

def content(path):
with open(path) as fd:
return fd.read()


and the most "safer" version

def content(path):
with open(path) as fd:
text = fd.read()
return text


The 1-liner is quite attractive and could be used often as a callback implementation (for example in in GUI environment) but I don't know if it is safe to use in production or if it is consider Pythonic.


EDIT: another example using the descriptor io.BytesIO and PIL.Image

Open/close version:

def array2bytes_image(a:np.array, out_format:str='PNG') -> bytes:
"""Numpy array - 1:1 -> image as bytes"""
im = Image.fromarray(a, mode='L') # 8-pixel grayscale
bio_im = io.BytesIO()
im.save(bio_im, format=out_format.upper())
im_binary = bio_im.getvalue()
bio_im.close()
im.close()
return im_binary


Open + GC version: (less verbose)

def array2bytes_image(a:np.array, out_format:str='PNG') -> bytes:
"""Numpy array - 1:1 -> image as bytes"""
im = Image.fromarray(a, mode='L') # 8-pixel grayscale
bio_im = io.BytesIO()
im.save(bio_im, format=out_format.upper())
return bio_im.getvalue()

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