Delete Python Object without deleting all references first

Question

Easy question, is it possible to remove an object from memory and setting all remaining pointers to it to undefined?

Do you mean forcibly dereference it from all of the identifiers/containers currently holding a reference to it? Could you expand on the context of the problem you're actually trying to solve? — jonrsharpe, Jun 28 '18 at 21:11
you mean this ( https://stackoverflow.com/questions/5844672/delete-an-element-from-a-dictionary ) — kadalamittai, Jun 28 '18 at 21:12
[This](https://stackoverflow.com/q/3013304/1586200) question may help if that's what you mean. — Autonomous, Jun 28 '18 at 21:13
In case someone tries to recommend `pyjack.replace_all_refs`: no, that can't actually get all the references, it just tries its best, the name is misleading. — user2357112, Jun 28 '18 at 21:13
Possible duplicate of [How can I explicitly free memory in Python?](https://stackoverflow.com/questions/1316767/how-can-i-explicitly-free-memory-in-python) — MoxieBall, Jun 28 '18 at 21:20
@MoxieBall nope. That simply runs the supplemental garbage collector, which only handles unreachable reference cycles. — juanpa.arrivillaga, Jun 28 '18 at 21:38
@juanpa.arrivillaga I agree that the accepted answer doesn't answer this question but many of the rest do. Perhaps that wasn't enough of a reason to mark this as a dup — MoxieBall, Jun 28 '18 at 21:44
Possible duplicate of [How to delete every reference of an object in Python?](https://stackoverflow.com/questions/3013304/how-to-delete-every-reference-of-an-object-in-python) — Jacob, Jun 28 '18 at 23:13

score 2 · Accepted Answer · answered Jun 28 '18 at 21:20

2

You cannot explicitly free memory in Python.

If you want to call del x without having other references to x preventing it from getting garbage collected, you may want to check out weakrefs.

answered Jun 28 '18 at 21:20

MoxieBall

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score 0 · Answer 2 · answered Jun 28 '18 at 21:41

In case you are looking to create some sort of 'cancelable' object that can be invalidated and cause all subsequent attempts to use it to get either a None value or an error, you can do that (after a fashion), but your code will have to be disciplined not to get a direct reference ever, but always refer to the object in a special way, for example:

class deletable(object):
    def __init__(self, value):
        self.v = value
    def destroy(self):
        if hasattr(self,"v"): delattr(self, "v")

# create instance
x = deletable( { "key" : "value", "other" : 13 } )

# access
print (x.v["key"])

# re-assign
x.v = { "another" : "dict" }

# "destroy" - option 1 - trigger error on use
x.destroy()

# "destroy" - option 2 - make it None (free memory, but keep x.v valid)
x.v = None # or x.v = {}, if you want to keep it with the original data type of dict()

Now, this "works" on the condition that you never (EVER) do z = x.v and always pass around x as a whole.

(If you know in advance the data type and it is always the same, e.g., dict, you can do a bit better and have the custom object respond to things like x["key"], x.update(some_dict), etc., i.e., look like a regular dict, but still able to call x.destroy() and make it fail further attempts to access. Advanced stuff, I won't write a whole article here on this, not even knowing that I made a correct guess as to what you really need).

Delete Python Object without deleting all references first

2 Answers2