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Suppose I have file foo.py:

def foo():
 print("foo")

And I start an interactive session:

>>> import foo 
>>> foo.foo()
'foo'

Next, I add a function to the python file:

def bar():
  print("bar")

And I update my interactive session:

>>> import foo
>>> foo.bar()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'bar' is not defined

So I realize I forgot that the import is cached:

>>> from importlib import reload
>>> reload(foo)
>>> foo.bar()
'bar'

Is there an easy way to have the interactive session continuously update with any changes that accumulate in foo.py?

I had to add this for clarity, since there are a variety of ways this question can be misunderstood:

The specific purpose of this question is to be able to work in interactive mode EXACTLY the way interactive mode should be worked in, and be able to call functions that are written dynamically in another window, buffer, or context after a write to drive, WITHOUT entering reload.

In other words, I would like to eliminate unnecessary keystrokes (CTRL-R reload ENTER, for example) every time I pop back and forth between buffers.

Is there an easy way?

(it is ok if the answer is "NO")

Solutions that might create a solution, but are not "easy":

  • a pile of code
  • an interpreter-within-an-interpreter loop
  • an application
  • a novel interpreter effort
  • a new ide company

An example of an easy way something similar is done:

  • pip install --editable my-dev-module
Chris
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  • Does this answer your question? [How do I unload (reload) a Python module?](https://stackoverflow.com/questions/437589/how-do-i-unload-reload-a-python-module) – Juan Medina Mar 30 '21 at 19:58
  • It seems this falls into a duplicated question (https://stackoverflow.com/questions/437589/how-do-i-unload-reload-a-python-module) – Juan Medina Mar 30 '21 at 19:58
  • @JuanMedina no, that is not relevant to my question – Chris Mar 30 '21 at 19:59
  • @JuanMedina I am asking how to continuously reload. I have already used `reload` in my question, so how could that be knowledge that I am seeking? – Chris Mar 30 '21 at 20:00
  • You see the loop on the answer? `from importlib import reload import foo while True: # Do some things. if is_changed(foo): foo = reload(foo)` – Juan Medina Mar 30 '21 at 20:00
  • @JuanMedina that is an answer. Not a question. How can anyone reach an answer that is not searchable via the call of the question? – Chris Mar 30 '21 at 20:01
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    @JuanMedina it does not work. The point of this question is to remove the `reload` ritual in interactive mode. Not to "do something in a while loop" – Chris Mar 30 '21 at 20:04
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    This is probably not possible because of the way python's `import` works -- it searches for the named module, then it binds the results of that search to a name in the local scope. This binding doesn't track the original module to detect changes, so unless you write an interpreter or a REPL that does that (which you don't want), reloading is the only way. – Pranav Hosangadi Mar 30 '21 at 20:22

1 Answers1

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As per your comments you clarified you don't need to use reload. Although, I will list all the possible options I found. For Pythn you have only 2 options:

  • use of reload(foo) (I know this is not the way you want, but exists)

  • use of importlib.reload(foo):

    import importlib
importlib.reload(foo)

That's the only 2 options you have. Now, if you are using IPython, you have 2 more options:

  • use %run: %run foo.py
  • use %autoreload: the option you would be looking for is %aimport foo

For the entire explanation: https://switowski.com/blog/ipython-autoreload

If that doesn't answer your question, the the simple would be: Without using the first 2 option, it's not possible to do so

Juan Medina
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