Use required-features to gate expressions example with tensorflow_unstable feature

Fixes #64

Author: adamcrume

Cargo.toml

@@ -21,3 +21,16 @@ random = "0.12"
 tensorflow_unstable = []
 
 [workspace]
+
+[[example]]
+name = "addition"
+
+[[example]]
+name = "expressions"
+required-features = ["tensorflow_unstable"]
+
+[[example]]
+name = "regression"
+
+[[example]]
+name = "regression_savedmodel"

examples/expressions.rs

@@ -5,8 +5,6 @@ use std::error::Error;
 use std::result::Result;
 use std::process::exit;
 use tensorflow::Code;
-// Workaround for https://github.com/rust-lang/cargo/issues/1570
-#[cfg(feature = "tensorflow_unstable")]
 use tensorflow::expr::{Compiler, Placeholder};
 use tensorflow::Graph;
 use tensorflow::Session;
@@ -60,16 +58,6 @@ impl Checker {
     }
 }
 
-// Workaround for https://github.com/rust-lang/cargo/issues/1570
-#[cfg(not(feature = "tensorflow_unstable"))]
-fn run() -> Result<(), Box<Error>> {
-    println!("examples/expressions.rs is disabled because the `tensorflow_unstable` feature is \
-              not enabled!");
-    Ok(())
-}
-
-// Workaround for https://github.com/rust-lang/cargo/issues/1570
-#[cfg(feature = "tensorflow_unstable")]
 fn run() -> Result<(), Box<Error>> {
     // Build the graph
     let mut g = Graph::new();