64 lines
1.5 KiB
Markdown
64 lines
1.5 KiB
Markdown
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# Envhead
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Envhead is a crate that creates environment variable names using a static prefix. The desired prefix is defined in your build script `build.rs`.
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### Usage
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First, you should define the prefix in your `build.rs` file. In this example, we will use `MY_APP` as the prefix:
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```rust
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fn main() {
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println!("cargo:rustc-env=ENV_HEAD_PREFIX=MY_APP");
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}
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```
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When the `ENV_HEAD_PREFIX` variable is not defined, `ENV` is used as the default prefix.
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Then, in your code, you can use the `envhead!` macro to create environment variable names.
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```rust
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use envhead::envhead;
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fn main() {
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let env_var = envhead!("server_port");
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// Prints "MY_APP_SERVER_PORT":
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println!("{}", env_var);
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}
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```
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You might find it useful to use `envhead` together with `clap` to create environment variable names for your command line arguments:
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```rust
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use clap::Args;
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use envhead::envhead;
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#[derive(Debug, Args)]
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pub struct ServerArgs {
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#[arg(
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short = 'p', long,
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required = false,
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value_name = "port",
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value_hint = clap::ValueHint::Other,
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help = "The server's port.",
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default_value_t = 8000,
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env = envhead!("server_port"),
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)]
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pub port: u16,
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#[arg(
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long,
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required = true,
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value_name = "SECRET_TOKEN",
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value_hint = clap::ValueHint::Other,
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help = "The secret token to authenticate the client.",
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env = envhead!("server_secret_token"),
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)]
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pub secret_token: Option<String>,
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}
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```
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# Changelog
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### Version 1.0.0
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- Initial release
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