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This is also somewhat common in c++ with immediate-invoked lambdas
by Rucadi 10mo ago
This is also somewhat common in c++ with immediate-invoked lambdas
- carstimon 10mo agoA blog post for it from a prominent c++er https://herbsutter.com/2013/04/05/complex-initialization-for-a-const-variable/ https://herbsutter.com/2013/04/05/complex-initialization-for...
- jeroenhd 10mo agoThe same pattern can also be useful in Rust for early returning Result<_,_> errors (you cannot `let x = foo()?` inside of a normal block like that). let config: Result<i32, i32> = { Ok( "1234".parse::<i32>().map_err(|_| -1)? ) }; would fail to compile, or worse: would return out of the entire method if surrounding method would have return type Result<_,i32>. On the other hand, let config: Result<i32, i32> = (||{ Ok( "1234".parse::<i32>().map_err(|_| -1)? ) })(); runs just fine. Hopefully try blocks will allow using ? inside of expression blocks in the future, though.
- knorker 10mo agoYeah but languages that make you resort to this then don't let you simply return from the block. And the workarounds often make the pattern be a net loss in clarity.