The implementation of "template method" design pattern usually utilizes a base class and a derived class: The base class will define a workflow and the derived class override method in the workflow.
However, Rust doesn't have "inheritance". While I am not sure if this is a correct way to do, but I found that we can use the trait feature to implement the same thing.
First we define a BaseHandler trait to define the workflow: in the get function we call authorized and do_get function. Then our "derived" class UserHandler will implement this trait with overriding those 2 methods.
trait BaseHandler {
fn authorized(&self) -> bool {
false
}
fn get(&self) -> String {
if !self.authorized() {
return "403 Forbidden".to_string();
}
println!("Do some basic work");
// handle rest work to do_get
self.do_get()
}
fn do_get(&self) -> String;
}
struct UserHandler;
impl BaseHandler for UserHandler {
fn authorized(&self) -> bool {
true
}
fn do_get(&self) -> String {
"Processed by User handler".to_string()
}
}
fn main() {
let handler = UserHandler {};
println!("{}", handler.get());
}
Result:
Do some basic work
Processed by User handler
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