Comments on: A Better Python Reload

By: John

John — Mon, 26 Apr 2010 11:33:44 +0000

Coming from Lisp, Python looks more and more like a joke prod
and less like a serious general purpose DYNAMIC language. The fact that i can not selectively update the code i want without losing state and without resorting to reload tricks that seem to copy the worst of Erlang is a big hindrance.

Erlang may have code update but it is only one step above Python’s.
For the ultimate in live-coding and productivity boost check out Common Lisp or Smalltalk. This is what all dynamic languages should strive for.

By: admin

admin — Sun, 14 Feb 2010 21:26:06 +0000

Thanks for the improvements. Reload is full of complications and corner cases especially in a dynamic language like Python. I think it is impossible to make it fool-proof.

By: gatorade

gatorade — Thu, 11 Feb 2010 07:22:25 +0000

correction to the pastebin above, forgot this line in the update loop:

mod.__dict__[key] = old_obj

By: gatorade

gatorade — Wed, 10 Feb 2010 21:13:17 +0000

There is at least one problem with this reload:

I have a module that imports the “parse_qsl” function from urlparse. When I try your reload on this module, parse_qsl loses its default parameters and complains that I’m not calling it properly.

Take a look at the superreload function here:

http://www.cherrypy.org/attachment/wiki/AutoReload/autoreload.py

It’s very slow and wasteful with memory, but it seems to be more reliable. I haven’t had any such problems with it.

I’m now using this combination of both methods:

http://pastebin.com/f14287ce5

This seems to solve everything pretty well. Am I missing anything? Could it be optimized any more?

By: Yuri Baburov

Yuri Baburov — Mon, 18 Jan 2010 10:05:28 +0000

As for your reload(), you might try to use gc.get_objects to find all instances belonging to mod (.__module__ key), and update them to new module.

By: Yuri Baburov

Yuri Baburov — Mon, 18 Jan 2010 09:58:37 +0000

Please change the last 3 lines of code to

class a:
def make(self):
class b: pass
return b

since your variant throws “SyntaxError: invalid syntax” (at least in Python 2.5).