Is it possible to initialize a variable from an environment variable at compilation time when using no_std?

▼魔方 西西 提交于 2019-12-11 17:30:06

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

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