CODEWITHSUNDEEP
pythonclassmemoryreturncode-cleanup
Alex Merson
Alex Merson

Reputation: 687

Python: automatically delete class object after return statement

I have a class that contains a function inside which I build and store a potentially very large bumpy array which I read form an HDF5 file. (I store the array as a class object so that when I read the various HDF5 datasets from the file I can use a list comprehension rather than a manual loop.) What I would like is to return and delete the stored array simultaneously (i.e. clean up the memory after the return statement).

class MWE(object):
      def __init__(self,*args):
          pass
          return

      def example(self,**kwargs):
          self.array = readLargeArrayFromHDF5File(...)
          return self.array # And simultaneously clean up self.array?

I know that I could simply delete the array using something like del MWE.array later on in my script, but is there any way to automatically clean up without me having to remember to do this?

Thanks!

Upvotes: 1

Views: 3465

Answers (1)

Asav Patel
Asav Patel

Reputation: 1162

you ned to use context manager for this kind of stuff! it automatically clears object when it gets out of the with code block.

from contextlib import contextmanager


class MWE(object):

    def __init__(self, *args):
        pass
        return

    @contextmanager
    def example(self, **kwargs):
        array = readLargeArrayFromHDF5File(...)
        try:
            yield array
        finally:
            array = None

    @contextmanager
    def example_two(self, **kwargs):
        array = readLargeArrayFromHDF5File(...)
        try:
            for item in array:
                yield item
        finally:
            array = None
# usage
with mwe_obj.example_two(kwargs) as result:
    for r in result:
        # work with your result here
        print (r)

# when your code hits this block self.array would get set to None
print ('cleared large array')

Upvotes: 3

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