问题
I would like to initialize a variable during compilation time. For example, I would like to initialize the variable VAR
to VALUE
when compiling the code:
match env::var("VAR") {
Ok(value) => println!("Ok {}", value),
Err(e) => println!("Error ({})", e),
};
However, I wanted to do it in a no_std
context, therefore, I cannot use std::env
to access the environment. Is it possible to do this?
回答1:
env::var does not get evaluated at compile time:
Fetches the environment variable key from the current process.
You are looking for std::env! / core::env! or std::option_env! / core::option_env!.
来源:https://stackoverflow.com/questions/51620782/is-it-possible-to-initialize-a-variable-from-an-environment-variable-at-compilat