Implement println! using nested format_args!
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`concat!` prevents `format_args!` from capturing variables from the
surrounding scope. Implementing `println!` using a nested `format_args!`
removes this limitation allowing us to do the following:
```rust
let x = 3;
println!("{x}");
```
Similar to `std::println!`.
Also, the change [does not impact performance][1].
[1]: rust-lang/rust#106824
Signed-off-by: Klimenty Tsoutsman <[email protected]>
kevinaboos
approved these changes
Jun 26, 2023
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Nice, I was wondering about doing that sort of variable capturing in custom format macros!
There are a few other places where we do this similar concat!() pattern, a few I can think of off the top of my head are early_printer, println_log!() in the deps app, etc. Would you mind submitting similar PR(s) for those?
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Our previous usage of `concat!()` prevents `format_args!`
from capturing variables from the surrounding scope.
Implementing `println!` using a nested `format_args!`
removes this limitation allowing us to do the following:
```rust
let x = 3;
println!("{x}");
```
Signed-off-by: Klimenty Tsoutsman <[email protected]> 2d6e8b4
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concat!preventsformat_args!from capturing variables from the surrounding scope. Implementingprintln!using a nestedformat_args!removes this limitation allowing us to do the following:Similar to
std::println!.Also, the change does not impact performance.