I'm trying to show people that exceptions are a very nice thing to have
when it comes to detecting when something went awry somewhere. I'd like
a real-world case, though.
Here's what I'm sort of coming up with --- given my limited experience
and imagination. Below, you have f calling g caling h calling j which
returns True or False based on a random thing. (This simulates a task
that sometimes succeeds and sometimes fails.) If while at f() I want to
know what happened at j(), I'm going to have to propagate that
information upwards through the execution stack. I can't do that right
now: I'd have to change f, g and h.
--8<---------------cut here---------------start------------->8---
from random import randint
def f():
g()
def g():
h()
def h():
if j():
print("I got a 2.")
else:
print("I got a 1.")
def j():
return randint(1,2) == 2
--8<---------------cut here---------------end--------------->8---
If instead of that, j() would be raising an exception when it fails,
then all I only need to change f() to know what happens.
I could replace j's test with opening a file, say. That would improve
it a little. I'm sure you guys know excellent cases to show. Would you
be so kind to share anything you might have in mind?
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