Add simple example using lazy_static

Signed-off-by: Matthias Beyer <[email protected]>

Author: matthiasbeyer

examples/static_env.rs

@@ -0,0 +1,20 @@
+use config::Config;
+
+lazy_static::lazy_static! {
+    #[derive(Debug)]
+    pub static ref CONFIG: Config = Config::builder()
+        .add_source(config::Environment::with_prefix("APP_NAME").separator("_"))
+        .build()
+        .unwrap();
+}
+
+/// Get a configuration value from the static configuration object
+pub fn get<'a, T: serde::Deserialize<'a>>(key: &str) -> T {
+    // You shouldn't probably do it like that and actually handle that error that might happen
+    // here, but for the sake of simplicity, we do it like this here
+    CONFIG.get::<T>(key).unwrap()
+}
+
+fn main() {
+    println!("{:?}", get::<String>("foo"));
+}