Use ? operator instead of unwrap in all examples/docs

[sunjay]

In the Rust API Guidelines, it talks about how we should prefer to use the ? operator instead of unwrap() in our examples/docs because people often copy/paste directly from the docs. (See the full justification at that link.)

Since main() can now return a Result we can actually do this everywhere.

I know rust-sdl2 has been around for much longer than these features, so I'm wondering if you would even be interested in someone (maybe even me!) doing the work to convert all of the examples to use the ? operator.

Doing this conversion actually reveals some interesting things like how there are inconsistencies in the error types returned by the methods. Most methods return an error type of String but some don't and this makes using ? absolutely everywhere hard. Part of this work could be unifying everything under a single SDLError error type. (Maybe better completed separately since it's a breaking change.)

Any line that can't be converted to use ? instead of unwrap should at least use expect with a nice message so people know what happened.

Checklist

• More idiomatic error handling in examples/ (Improved Exaple Error Handling: Replaced all calls to unwrap() in examples with either the ? operator or expect() #839)
• More idiomatic error handling in documentation examples

[Cobrand]

You raise 2 issues so I'm going to answer each one:

• For the doc, replacing unwrap with ? seems great!
• For the error returned by this lib, I know that sometimes we return a string and sometimes something else... But this is so hard so group them all that we let it that way. Arguably, we could create a struct that would impl From<Error1>, From<Error2>, ect, but never use it in this project (just so that you can group every SDLError into one struct/enum), but it doesn't seem that useful to me.

[sunjay]

For the doc, replacing unwrap with ? seems great!

Great! I'm current working on this and I will open a PR shortly.

but never use it in this project (just so that you can group every SDLError into one struct/enum), but it doesn't seem that useful to me.

I agree that's probably not a good idea. One thing I would like to see is String get replaced with an SDLError(String) type or something. What do you think about doing that? Such a type already exists in the render module, though it isn't used widely. This is a breaking change, so I certainly wouldn't suggest doing it as part of this issue, however, I would really want that before 1.0.0.

[sunjay]

@Cobrand The PR is up: #839 🎉

[sunjay]

I might not get a chance to work on this for a while, so this might be a good first issue for anyone looking to contribute. You can look at my PR for the kinds of changes you should be looking to make. My PR description is also informative. Feel free to comment here if you have any questions. I'll try to help. :)