Hi! First of all thank you so much for the detailed explanation!
What I'm trying to do is scraping some content.
Yes I'm trying to return all links (maybe in a vector), I have a list of elements (Select, which actually is scraper::html::Select<'_, '_>) which contain essentially html nodes selections, and I would like to grab each of them, extract the actual link value (&str), convert it into an actual String and push it firstly into a vector containing all the links and then in an istance of a struct which will contain several datas about the scraped page later.
I was trying to use a for loop because that was the first structure that came to my mind, I'm finding it hard to wrap my head around ownership and error handling with rust, using the if let construct can be a good idea, and I didn't consider the use of break!
I also managed to build the "match version" of what I was trying to achieve:
fn get_links(link_nodes: scraper::html::Select<'_, '_>) -> Vec<String> {
let mut links = vec![];
for node in link_nodes {
match node.value().attr("href") {
Some(link) => {
links.push(link.to_string());
}
None => (),
}
}
dbg!(&links);
links
}
I didn't understand that I had to return the same type for each of the Option match arms, I thought enum variants could have different types, so if the Some match arm returns (), also None has to do the same..
If I try with a simpler example I still cannot understand why I cannot do something like:
enum OperativeSystem {
Linux,
Windows,
Mac,
Unrecognised,
}
let absent_os = OperativeSystem::Unrecognised;
find_os(absent_os);
fn find_os(os: OperativeSystem) -> String {
match os {
debian => {
let answer = "This pc uses Linux";
answer.to_string()
}
windows10home => {
let answer = "This pc uses Windows, unlucky you!";
answer.to_string()
}
ios15 => {
let answer = "This pc uses Mac, I'm really sorry!";
answer.to_string()
}
_ => {
let is_unrecognised = true;
is_unrecognised
}
}
}
match is much more intuitive for a beginner, there's a lot of stuff which go under the hood with ?
Thank you so much, You are taking a lot of effort to answer my doubts and I really appreciate!
So essentially match can return different types, but of course I have to specify it in the function signature, wheter using an enum or other ways, this makes sense! This was a missing piece in my puzzle, I didn't consider the fact that the match return here was the function return type as well, and i had encoded
-> Stringas return type.