--- a/rust/src/config.rs	Sat Jan 07 00:56:39 2017 +0800
+++ b/rust/src/config.rs	Tue Feb 07 21:56:58 2017 +0800
@@ -1,6 +1,8 @@
 extern crate toml;
 
-use serde::Serialize;
+use std::fs::File;
+use std::io::Read;
+use serde::{Serialize,Deserialize,Deserializer,Serializer};
 
 #[derive(Deserialize,Serialize,Debug,Clone)]
 #[allow(non_snake_case)]
@@ -31,7 +33,7 @@
 
 impl Config {
 
-    pub fn new() -> Self {
+    pub fn default() -> Self {
         Config {
             SENSOR_SLEEP: 5,
             UPLOAD_SLEEP: 83,
@@ -68,34 +70,40 @@
         toml::Value::Table(e.toml).to_string()
     }
 
-    /*
-    pub fn parse(&mut self, s: &str) {
-        let filename = "tempserver.conf";
 
-        let f = File::open(filename)
+    pub fn merge(&self, conf: &str) -> Result<Self, String>{
+        let mut p = toml::Parser::new(&conf);
+        p.parse()
+            .ok_or_else(|| {
+                format!("toml parsing failed: {:?}", p.errors)
+            })
+            .map(|mut new_toml| {
+                let mut e = toml::Encoder::new();
+                self.serialize(&mut e).unwrap(); // XXX what could go wrong?
+                let mut ex_toml = e.toml;
+                ex_toml.append(&mut new_toml);
+                let mut dec = toml::Decoder::new(toml::Value::Table(ex_toml));
+                Self::deserialize(&mut dec).unwrap() // could this go wrong?
+            })
+    }
+
+    pub fn merge_file(&self, filename: &str) -> Result<Self, String>{
+
+        let r = File::open(filename)
             .map_err(|e| e.to_string())
             .and_then(|mut f| {
                 let mut s = String::new();
                 f.read_to_string(&mut s)
                     .map_err(|e| e.to_string())
                     .map(|_| s)
-            })
-            .and_then(|s| {
-                    
-                        .map_err(|e| e.to_string())
             });
 
-        match f {
-            Ok() => {
-
-            },
-            Err(e) => {
-                debug!("Error loading config file {}: {}",
-                    filename, e);
-
-            }
-        }
-
+        r.and_then(|s| {
+            self.merge(&s)
+        })
+        .map_err(|e| {
+            format!("Error loading config file {}: {}",
+                    filename, e)
+        })
     }
-    */
 }