Better Alternative for Box::leak() in this case

[mortal belfry]

    ( for $arg1:ident in $arg4:expr  ) => {
        {
            let mut vec = Vec::new();
            for $arg1 in $arg4{
                vec.push($arg1);
            }
            vec
        }
    };
    ( for $arg1:ident in $arg4:expr => String ) => {
        {
            let mut vec = Vec::<String>::new();
            for $arg1 in $arg4{
                vec.push($arg1.to_string());
            }
            vec
        }
    };

      ( for $arg1:ident in $arg4:expr => &str ) => {
        {
            let mut vec = Vec::<&str>::new();
            for $arg1 in $arg4{
                let string_value = Box::leak(Box::new($arg1.to_string()));  
                vec.push(string_value.as_str());
            }
            vec
        }
    };
}
fn main() {
    let a = expr!(for i in (0 ..= 10).rev() => String);
    let a = expr!(for i in (0 ..= 10).rev() => &str);
    println!("{:?} ",a);
    let a = "".to_string().to_owned().as_str();
}

[prime grail]

Yes, there are better ways? But I am not sure what you are trying to accomplish.

This would cause memory leaks whenever the macro is encountered.

If the goal is to create a Vec of strings or string slices you can also just use the collect method.

[mortal belfry]

I just wana convert String => &'static str

But as per I researched it's not posssible

Cause a reference to String will be valid up to the life time of String

[random fox]

Whenever you find yourself wanting to do this, the first question to answer is "why"

The second question is "is there another way to solve the actual problem"

[mortal belfry]

So basically I wana

Convert integer to &'static str so I moved with a solution that says use concat!() but it works only with String

[mortal belfry]

Basically I had made a macro that takes an expression and do iteration and return a vector

But I want that vector to contain something like ["1","2"...]

A &'static str

[random fox]

Yeah, I see the macro. As besta as I can tell, you could just make the vector store Strings instead

[random fox]

macro_rules! cannot do this with &str without leaking. You might be interested in the seq_macro crate, which you can use with stringify!

[mortal belfry]

What's that seq_macro.??

[random fox]

?crate seq_macro

[cunning tapir]

seq-macro

Macro to repeat sequentially indexed copies of a fragment of code.

Version

0.3.5

Downloads

17 010 901

Jul 15, 2023, 7:24 PM

[mortal belfry]

Oh

[mortal belfry]

Is it not possible to convert String to &'static str without macro_rule! simply in main

Cause as per what I read on stack overflow it says it's no safe way of doing this

[random fox]

There is nothing special about main, so no.

[kind orbit]

There is still the question of why do you need a &'static str

[mortal belfry]

Cause I can't return a reference of String from a block of code

[random fox]

Then just return the String instead

[mortal belfry]

Yeah I did it