But this means you have to litter your application with support for it, doesn't it? In Common Lisp, I can stop at a breakpoint, paste in a new definition of any function in the application, and then resume and it will use the new definition everywhere rather than the one that existed when the breakpoint was triggered: https://two-wrongs.com/debugging-common-lisp-in-slime.html
*and not only paste, but write, in the source file, the new definition, re-compile it (C-c C-c), and resume execution from a stackframe before this call. (a clarification for folks who would think we must paste in the REPL)
Reload only reloads one copy of the module. If there are other modules that imported the same module, your new definition will not be seen by them unless you find all the copies of foo in memory and reload them also. Since there's no reliable way to do that, you're more likely to just restart Python all the time.
Not accurate as worded. Python caches module imports in `sys.modules`, so all imports get the same one. A `reload()` will reuse the same dict object that was being used as the module's namespace, so everything with a reference to the module object will see the same namespace and get the updates.
You can also use `from importlib import reload` and then have an expression like reload(foo).bar() to constantly reload your foo library.