Refactor code

- use invalid_arg!
- remove std result alias
- fix getting char pointer to export_dir

Author: Enet4

src/session.rs

@@ -4,7 +4,6 @@ use std::ffi::CString;
 use std::marker;
 use std::path::Path;
 use std::ptr;
-use std::result::Result as StdResult;
 use super::Code;
 use super::DataType;
 use super::Graph;
@@ -44,27 +43,23 @@ impl Session {
          -> Result<Self> {
         let mut status = Status::new();
 
-        let export_dir_cstr = try!(export_dir.as_ref()
-                                       .to_str()
-                                       .and_then(|s| CString::new(s.as_bytes()).ok())
-                                       .ok_or_else(|| {
-            Status::new_set(Code::InvalidArgument, "Invalid export directory path").unwrap()
-        }));
+        let export_dir_cstr =
+            try!(export_dir.as_ref()
+                     .to_str()
+                     .and_then(|s| CString::new(s.as_bytes()).ok())
+                     .ok_or_else(|| invalid_arg!("Invalid export directory path")));
 
         let tags_cstr: Vec<_> = try!(tags.into_iter()
                                          .map(|t| CString::new(t.as_ref()))
-                                         .collect::<StdResult<_, _>>()
-                                         .map_err(|_| {
-            Status::new_set(Code::InvalidArgument, "Invalid tag name").unwrap()
-        }));
+                                         .collect::<::std::result::Result<_, _>>()
+                                         .map_err(|_| invalid_arg!("Invalid tag name")));
         // keeping tags_cstr to retain strings in memory
         let tags_ptr: Vec<*const c_char> = tags_cstr.iter().map(|t| t.as_ptr()).collect();
 
         let inner = unsafe {
             tf::TF_LoadSessionFromSavedModel(options.inner,
                                              ptr::null(),
-                                             export_dir_cstr.to_bytes_with_nul().as_ptr() as
-                                             *const c_char,
+                                             export_dir_cstr.as_ptr(),
                                              tags_ptr.as_ptr(),
                                              tags_ptr.len() as c_int,
                                              graph.inner(),
@@ -351,3 +346,4 @@ mod tests {
         assert_eq!(data[1], 6.0);
     }
 }
+