update readme

1 files changed, 47 insertions, 14 deletions

diff --git a/README.md b/README.md
index 2847e32..4719ee0 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,8 @@ extern crate notmuch;
 
 ```rust
 extern crate notmuch;
+use notmuch::StreamingIterator;
+
 
 fn main() {
 
@@ -40,13 +42,8 @@ fn main() {
     let query = db.create_query(&"".to_string()).unwrap();
     let mut threads = query.search_threads().unwrap();
 
-    loop {
-        match threads.next() {
-            Some(thread) => {
-                println!("thread {:?} {:?}", thread.subject(), thread.authors());
-            },
-            None => { break }
-        }
+    while let Some(thread) = threads.next() {
+        println!("thread {:?} {:?}", thread.subject(), thread.authors());
     }
 }
 
@@ -59,13 +56,49 @@ thread locals, but I did not spot any locks. So, as far as I am concerned, it is
 not thread safe.  
 So why do all structs implement ```Send``` and ```Sync```? Well, it _is_ safe to
 access pointers from different threads (as long as you know what you are doing :) ).
-But, more importantly, all structs are strictly linked together with their
-lifetime. The root of the tree is ```notmuch::Database```, which has a lifetime
-that must outlive any related objects, for instance ```notmuch::Query```. The
-```notmuch::Threads``` iterator that you can get from a ```notmuch::Query``` is
-always outlived by the parent query.  
-This means that you can only use these structs accross thread bounds if you
-figure out how to satisfy the lifetime requirements.
+Up till now I haven't done a lot of multithreaded stuff with notmuch-rs. If you
+feel this is too permissive, let me know.
+
+## Lifetime
+
+All structs are strictly linked together with their lifetime. The root of the
+tree is ```Database```, which has a lifetime that must outlive any child
+objects, for instance ```Query```. The ```Threads``` iterator that you can get
+from a ```Query``` is always outlived by the parent query. ```Threads``` in its
+turn must have a longer life than ```Thread```, which in turn must outlive
+```Messages``` and so on. Each structure keeps a ```PhantomData``` marker of its
+owner.
+
+Using this in an application poses significant difficulties in satisfying these
+lifetime requirements. To alleviate this, ```notmuch-rs``` makes use of the
+excellent [Supercow](https://crates.io/crates/supercow), so you don't have to
+use crates like ```owningref``` or ```rental``` to get around this.
+
+This way, you get to choose your own container type, and even keep the parent
+object alive so you don't have to juggle lifetimes. To use this, most types
+are accompagnied with an ```*Ext``` trait, that accepts ```Rc```, ```Arc``` or
+comparable.
+
+```rust
+    use std::sync::Arc;
+    use notmuch::{DatabaseExt};
+
+    let query = {
+        let dbr = Arc::new(db);
+
+        <Database as DatabaseExt>::create_query(dbr.clone(), &"".to_string()).unwrap()
+    };
+
+```
+
+## Iterators
+
+Since the lifetime of a ```Thread``` or a ```Message``` is dependent on the
+```Threads``` and ```Messages``` iterator respectively, using the regular rust
+```Iterator``` trait proved impossible. As such, ```notmuch-rs``` includes a
+```StreamingIterator``` (and additional ```StreamingIteratorExt```) trait that
+is used to iterate while satisfying the lifetime constraints.
+
 
 ## Acknowledgements