This Week I Learned: 2022W47

Rust

In Rust, what distinguishes a struct method from an associated function (in Python we could say a method from a static method) is simply the fact that the first parameter is self. Really reminds me of Python.

struct MyStruct {}

impl MyStruct {
    // Associated function
    fn my_associated_function(foo: String) {}

    // Method
    fn my_method(self, foo: String) {}
}

On the contrary to Python, self is meaningful and cannot be replaced with another label.

Also, Rust doesn’t allow named or keyword parameters, only positional parameters.

Rust - Todo macro

When writing Rust code, the compiler and linter can be a bit annoying because we specified a return type and we have not finished writing our function yet. If you want to get rid for now of the compiler errors about this, you can add the macro todo!() into your function.

You can find the documentation here.

Rust - Borrowing and references

You can have a reference of a reference of a reference of a ref…

Which means this is perfectly valid in Rust:

let foo = "foo";
let new_string = format!("My new string: {}", &&&&&&&&&&&foo);

Rust - Shorthand properties

Rust has shorthand property names as in Javascript.

struct Person {
    age: u8
}

// ...
let age = 18;

// Both are equivalent
Person({age: age});
Person({age});

Rust - Traits

You can implement a trait like this:

struct Person {}

impl Drop for Person {
    fn drop(&mut self) {}
}

You can read more about traits here. The Drop trait is interesting because it defines a method that will be called before the variable is dropped in memory.

SQL

You can use index integers in SQL’s GROUP BY and ORDER BY, relating to the columns in the SELECT statement (index starts at 1).

SELECT id, name
FROM account
ORDER BY 2;

is equivalent to:

SELECT id, name
FROM account
ORDER BY name;