It starts to look like something…

src/lib.rs

@@ -1,5 +1,8 @@
 // std
-use std::fs::read_to_string;
+use std::{
+    fs::{read_to_string, write},
+    error::Error,
+};
 
 // clap
 use clap::{App, Arg};
@@ -13,13 +16,33 @@ use egg_mode::{
     KeyPair,
     tweet::{
         user_timeline,
-        Tweet,
     },
 };
-
-// tokio
 use tokio::runtime::current_thread::block_on_all;
 
+/**********
+ * Generic usage functions
+***********/
+
+fn read_state(s: &str) -> Option<u64> {
+    let state = read_to_string(s);
+
+    if let Ok(s) = state {
+        return s.parse::<u64>().ok();
+    }
+
+    None
+}
+
+fn write_state(f: &str, s: u64) -> Result<(), std::io::Error> {
+    write(f, format!("{}", s))
+}
+
+/**********
+ * Config structure
+***********/
+
+/// General configuration Struct
 #[derive(Debug, Deserialize)]
 pub struct Config {
     twitter: TwitterConfig,
@@ -32,9 +55,11 @@ struct TwitterConfig {
     consumer_secret: String,
     access_key: String,
     access_secret: String,
+    last_tweet_path: String,
 }
 
 impl Config {
+    /// parses configuration from command line and TOML config file
     pub fn new() -> Config {
         let matches = App::new(env!("CARGO_PKG_NAME"))
                             .version(env!("CARGO_PKG_VERSION"))
@@ -61,19 +86,32 @@ impl Config {
     }
 }
 
+/*********
+ * Main function
+*********/
+
+/// This is where the magic happens
 pub fn run(config: Config) {
-    let con_token = KeyPair::new(config.twitter.consumer_key, config.twitter.consumer_secret);
-    let access_token = KeyPair::new(config.twitter.access_key, config.twitter.access_secret);
+    let last_tweet_id = read_state(&config.twitter.last_tweet_path);
+
+    let con_token = KeyPair::new(String::from(&config.twitter.consumer_key), String::from(&config.twitter.consumer_secret));
+    let access_token = KeyPair::new(String::from(&config.twitter.access_key), String::from(&config.twitter.access_secret));
 
     let token = Token::Access {
         consumer: con_token,
         access: access_token,
     };
 
-    let timeline = user_timeline(&config.twitter.username, false, false, &token)
+    let (_timeline, mut feed) = block_on_all(user_timeline(&config.twitter.username, false, false, &token)
                 .with_page_size(200)
-                .older(None);
+                .older(last_tweet_id)).unwrap();
 
-    timeline.types();
+    for tweet in &feed {
+        println!("{}: <@{}> {}", tweet.id, tweet.user.as_ref().unwrap().screen_name, tweet.text);
+    }
+
+    write_state(&config.twitter.last_tweet_path, feed[0].id).unwrap_or_else(|e|
+        panic!("Can’t write the last tweet retrieved: {}", e)
+    );
 }