functora-cli readme

Author: functora

rust/functora-cfg/Cargo.toml

@@ -1,7 +1,11 @@
 [package]
 name = "functora-cfg"
+license = "MIT"
 version = "0.1.0"
 edition = "2024"
+keywords = ["config", "configuration", "settings", "env", "environment"]
+repository = "https://github.com/functora/functora.github.io/tree/master/rust/functora-cfg"
+description = "A Rust library that merges configuration values from multiple sources into a single typed value."
 
 [dependencies]
 config = "0.15.18"

rust/functora-cfg/README.md

@@ -0,0 +1,122 @@
+# functora-cfg
+
+A Rust library that merges configuration values from multiple sources into a single typed value. Configuration values are applied in the following order:
+
+- Defaults
+- Config file
+- Environment variables
+- Command-line arguments
+
+All sources are optional. Only the ones you provide will be applied.
+
+## Example
+
+```rust
+use clap::{Parser, Subcommand};
+use functora_cfg;
+use serde::{Deserialize, Serialize};
+
+#[derive(
+    Debug, Clone, Serialize, Deserialize, PartialEq,
+)]
+pub struct Cfg {
+    pub conn: String,
+    pub logs: String,
+    pub many: Vec<String>,
+    pub nest: CfgNest,
+}
+
+#[derive(
+    Debug,
+    Clone,
+    Serialize,
+    Deserialize,
+    PartialEq,
+    Subcommand,
+)]
+pub enum CfgNest {
+    Nest { name: String, value: i32 },
+}
+
+#[derive(Debug, Clone, Serialize, Parser)]
+#[command(version, about)]
+pub struct Cli {
+    #[arg(long)]
+    pub toml: Option<String>,
+    #[arg(long)]
+    pub conn: Option<String>,
+    #[arg(long)]
+    pub logs: Option<String>,
+    #[arg(long)]
+    pub many: Option<Vec<String>>,
+    #[command(subcommand)]
+    pub nest: Option<CfgNest>,
+}
+
+fn new_cfg(cli: &Cli) -> Cfg {
+    let defaults = Cli {
+        toml: None,
+        conn: Some("postgres://localhost".into()),
+        logs: Some("/var/log/app.log".into()),
+        many: Some(vec!["a".into(), "b".into()]),
+        nest: Some(CfgNest::Nest {
+            name: "foo".into(),
+            value: 42,
+        }),
+    };
+
+    functora_cfg::Cfg {
+        default: &defaults,
+        file_path: |cli: &Cli| cli.toml.as_deref(),
+        env_prefix: "FUNCTORA",
+        command_line: cli,
+    }
+    .eval()
+    .unwrap()
+}
+
+fn main() {
+    let cfg = new_cfg(&Cli::parse());
+    println!("{:#?}", cfg);
+}
+```
+
+Run with defaults:
+
+```shell
+cargo run
+```
+
+Use a config file to override defaults:
+
+```shell
+cargo run -- --toml ./functora.toml
+```
+
+Example `functora.toml`:
+
+```toml
+conn = "postgres://remote"
+logs = "/tmp/app.log"
+many = ["x", "y", "z"]
+
+[nest.Nest]
+name = "file_nested"
+value = 99
+```
+
+Environment variables override defaults and file values:
+
+```shell
+FUNCTORA_CONN="./sqlite.db" cargo run -- --toml ./functora.toml
+```
+
+Command-line arguments override all other sources:
+
+```shell
+cargo run -- --toml ./functora.toml --conn "./functora.db"
+```
+
+<hr>
+
+© 2025 [Functora](https://functora.github.io/). All rights reserved.

rust/functora-cfg/src/lib.rs

@@ -1,3 +1,4 @@
+#![doc = include_str!("../README.md")]
 pub use config::ConfigError;
 use config::{Config, Environment, File, Value};
 use serde::{Serialize, de::DeserializeOwned};
@@ -26,12 +27,6 @@ where
     Src: Serialize,
     Dst: Serialize + DeserializeOwned,
 {
-    //
-    // TODO : use functional style with tierator over
-    // trait object array and try_fold into builder,
-    // maybe somthing else, this looks too bad:
-    //
-
     let mut builder = Config::builder();
 
     builder =