How can I use pickle to save a dict (or any other Python object)?

Question

I have looked through the information that the Python documentation for pickle gives, but I'm still a little confused. What would be some sample code that would write a new file and then use pickle to dump a dictionary into it?

Accepted Answer

Try this:

```
import pickle

a = {'hello': 'world'}

with open('filename.pickle', 'wb') as handle:
    pickle.dump(a, handle, protocol=pickle.HIGHEST_PROTOCOL)

with open('filename.pickle', 'rb') as handle:
    b = pickle.load(handle)

print(a == b)
```

There's nothing about the above solution that is specific to a `dict` object. This same approach will will work for many Python objects, including instances of arbitrary classes and arbitrarily complex nestings of data structures. For example, replacing the second line with these lines:

```
import datetime
today = datetime.datetime.now()
a = [{'hello': 'world'}, 1, 2.3333, 4, True, "x", 
     ("y", [[["z"], "y"], "x"]), {'today', today}]
```

will produce a result of `True` as well.

Some objects can't be pickled due to their very nature. For example, it doesn't make sense to pickle a structure containing a handle to an open file.

How can I use pickle to save a dict (or any other Python object)?

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