Replace Option with Result georust#1: added errors based using error-…

…chain

Cargo.toml

@@ -8,7 +8,8 @@ repository = "https://github.com/georust/rust-gdal"
 documentation = "https://georust.github.io/rust-gdal/"
 
 [dependencies]
-libc = "0.2.13"
+error-chain = "0.7.2"
+libc = "0.2.18"
 geo = "0.0.5"
 gdal-sys = { path = "gdal-sys", version = "0.1.0"}
 

src/errors.rs

@@ -0,0 +1,20 @@
+use libc::{c_int};
+
+// Create the Error, ErrorKind, ResultExt, and Result types
+error_chain! {
+    foreign_links {
+        FfiNulError(::std::ffi::NulError);
+        StrUtf8Error(::std::str::Utf8Error);
+    }
+
+    errors {
+        CplError(class: c_int, number: c_int, msg: String) {
+            description("GDAL internal error")
+            display("CPL error class: '{}', error number: '{}', error msg: '{}'", class, number, msg)
+        }
+        NullPointer(method_name: &'static str) {
+            description("GDAL method returned a NULL pointer.")
+            display("GDAL method {} returned a NULL pointer.", method_name) 
+        }
+    }
+}

src/lib.rs

@@ -20,11 +20,13 @@
 #![crate_name="gdal"]
 #![crate_type="lib"]
 
-
 extern crate libc;
 extern crate geo;
 extern crate gdal_sys;
 
+#[macro_use]
+extern crate error_chain;
+
 pub use version::version_info;
 
 mod utils;
@@ -33,8 +35,4 @@ pub mod metadata;
 pub mod version;
 pub mod raster;
 pub mod vector;
-
-#[derive(Clone, Copy, PartialEq, Debug)]
-pub struct GdalError {
-    pub desc: &'static str,
-}
+pub mod errors;