Re:Zero to Production in Rust
by tialaramex on Saturday June 05, 2021 @02:35PM
(#27407495)
I think analogous C++ code is a bug, the text might be a heap allocation (SSO may stash it inside the object) but surely the string object is local and lives on the stack. When the function returns that local object no longer exists and the reference to it is now dangling ?
I would say that the relationship between str and String was what most surprised me. I at first assumed the underlying primitive would be String since str is what you get when you borrow from a String, but it isn't. str is a built-in, whereas String is just a type defined in the (optional, this is a systems language) standard library.
If your environment can't afford memory allocation, you can't have Strings but you can use str just fine, that's a built-in. Since you lack allocators obviously you won't be going around minting new strings but str is perfectly fine for stuff like substring operations or comparisons.
I would say that the relationship between str and String was what most surprised me. I at first assumed the underlying primitive would be String since str is what you get when you borrow from a String, but it isn't. str is a built-in, whereas String is just a type defined in the (optional, this is a systems language) standard library.
If your environment can't afford memory allocation, you can't have Strings but you can use str just fine, that's a built-in. Since you lack allocators obviously you won't be going around minting new strings but str is perfectly fine for stuff like substring operations or comparisons.