2 releases
0.1.1 | Feb 28, 2023 |
---|---|
0.1.0 | Feb 28, 2023 |
#11 in #rewriting
4KB
chain-debug
Usage
use chain_debug::DebugExt;
struct A {
inner: B,
}
#[derive(Debug)]
struct B {
s: String,
}
impl A {
fn inner(&self) -> &B {
&self.inner
}
}
let a = A { ... };
a
.inner()
.debug()
.s
.debug()
Why?
Sometime I will write some code like:
let client = reqwest::Client::new();
let res = client
.post("example...")
.json(&payload)
.send()
.await
.unwrap()
.json::<Response>()
.await
.unwrap();
And there might be some error during the query, then the final json parser will get an unexpected JSON response that I need to figure out the actual content. But it is inconvenient to have to rewrite the code and break the chain call to debug.
let response = client.post(...).response();
println!("{response:?}")
What if we can...
// ...
.send()
.debug()
.json()
.debug()
Solution
We can inherit and extend the std::fmt::Debug
trait:
pub trait DebugExt {
fn debug(&self) -> &Self
where
Self: Debug,
{
println!("{self:?}");
self
}
}
impl<D: Debug> DebugExt for D {}
Then any struct that has the Debug
trait implied can automatically have
DebugExt
trait implied, so we can put .debug()
into the chain
and inspect the value without breaking the existing code.
Playground link: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=d283e02ea1b1041e04b21fc478f10271
Credit
Thanks to @SpriteOvO for teaching me about the trait inheritance part.