pythontemporary-files

Create a Tempfile with lifespan as the object


I have a project where I need to create temp files.

I have a class that accepts a file path. and as needed it reads the data from the file. However, sometimes I have the data and I want to create the same object so I use tempfile. But I want the file to be deleted as the object garbage-collected.

This is my implementation which is wrong.

from pickle import load
import tempfile


class A:
    def __init__(self, file_path):
        self.file_path = file_path

    @property
    def data(self):
        with open(self.file_path, "rb") as f2r:
            return load(f2r)

    @classmethod
    def from_data(cls, data):
        with tempfile.NamedTemporaryFile() as tmp:
            tmp.write(data)
            return cls(tmp.name)

The from_data method creates the temp file and returns an object but the file will be deleted as soon as from_data returns the object. But I want the file to live until the object itself is garbage-collected.


Solution

  • As @Nick ODell suggested I am going to use __del__ method to delete the file on garbage-collection.

    So the code would look like:

    from pathlib import Path
    from pickle import load
    import tempfile
    
    
    class A:
        def __init__(self, file_path):
            self.file_path = file_path
            self.is_temp = False
    
        def __del__(self):
            if self.is_temp:
                Path(self.file_path).unlink()
    
        @property
        def data(self):
            with open(self.file_path, "rb") as f2r:
                return load(f2r)
    
        @classmethod
        def from_data(cls, data):
            with tempfile.NamedTemporaryFile(delete=False) as tmp:
                tmp.write(data)
                a = cls(tmp.name)
                a.is_temp = True
                return a