#100DaysOfCode in Python Transcripts
Chapter: Days 25-27: Error handling
Lecture: Concepts: Error handling and exceptions
Login or
purchase this course
to watch this video and the rest of the course contents.
0:00
Let's quickly review the concepts
0:01
of try and except blocks in Python.
0:05
Python's primary error handling style
0:08
is what's called it's easier to ask
0:10
for forgiveness than permission.
0:13
As opposed to, say, C style of look before you leap.
0:16
In C you check, check, check, check, check,
0:18
and then you just try to do the thing and hope it works.
0:21
Typically what happens when it doesn't work
0:23
is either you get a false sort of return value there
0:26
or just the program just goes away, it's really bad.
0:28
Python is a little bit safer in that
0:30
it's more carefully captures up the errors
0:33
and converts them to exceptions.
0:35
So if it's going to do that anyway,
0:36
let's just try and make it work.
0:38
And if it doesn't work, well,
0:39
we'll catch it and deal with it in that case.
0:40
So it's kind of an optimistic way of handling errors.
0:44
so what we're going to do is we're
0:45
going to say try and do all the stuff,
0:47
and we're going to hope that it all just works
0:49
and kind of assume that it will just go through that block.
0:51
But if it doesn't, we're going to
0:53
drop into one of the specific error handling sections.
0:56
Here we have two possible errors,
0:58
really one that we're dealing with,
0:59
and the rest is kind of a catch all.
1:01
So we're saying except connection error as CE,
1:04
and then we're going to deal with that.
1:06
And in this case we might need to look inside the error
1:09
to see, well, was there a DNS problem,
1:11
is there a network problem,
1:13
did it not respond, things like that,
1:15
did we get a 500 back from the server, all kinds of things.
1:18
So this connection error,
1:19
we're going to catch and deal with that
1:21
and then we do this more general except block
1:24
where here's something we maybe didn't think of,
1:26
we're going to catch that and at
1:27
least try to somewhat not crash.
1:30
As we talked about before, the order matters.
1:31
Most specific goes first, most general last.
1:34
If you get that order wrong,
1:35
you'll never get to your specific errors.
1:37
So most specific, most general.
1:40
This is error handling in Python.
