Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Use hello_world instead of the guessing_game #16175

Merged
merged 2 commits into from
Aug 2, 2014
Merged

Use hello_world instead of the guessing_game #16175

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
ea92a5e
Use hello_world instead of the guessing_game
EduardoBautista Aug 1, 2014
69267b1
Move caret under the 'x' variabe
EduardoBautista Aug 1, 2014
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
28 changes: 14 additions & 14 deletions src/doc/guide.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -449,9 +449,9 @@ let x;
...we'll get an error:

```{ignore}
src/guessing_game.rs:2:9: 2:10 error: cannot determine a type for this local variable: unconstrained type
src/guessing_game.rs:2 let x;
^
src/hello_world.rs:2:9: 2:10 error: cannot determine a type for this local variable: unconstrained type
src/hello_world.rs:2 let x;
^
```

Giving it a type will compile, though:
Expand All @@ -460,7 +460,7 @@ Giving it a type will compile, though:
let x: int;
```

Let's try it out. Change your `src/guessing_game.rs` file to look like this:
Let's try it out. Change your `src/hello_world.rs` file to look like this:

```{rust}
fn main() {
Expand All @@ -474,10 +474,10 @@ You can use `cargo build` on the command line to build it. You'll get a warning,
but it will still print "Hello, world!":

```{ignore,notrust}
Compiling guessing_game v0.1.0 (file:/home/you/projects/guessing_game)
src/guessing_game.rs:2:9: 2:10 warning: unused variable: `x`, #[warn(unused_variable)] on by default
src/guessing_game.rs:2 let x: int;
^
Compiling hello_world v0.1.0 (file:/home/you/projects/hello_world)
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Does cargo really emit a bad file URL like that? file:/home/... is not correct, it should be file:///home/... (or sometimes file://home/... but that's not actually technically correct). I'd test it but I don't currently have cargo installed.

Copy link
Contributor Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@kballard Yes it does, this was my output:

Compiling hello_world v0.1.0 (file:/Users/eduardobautista/Projects/rust-guide)

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yes, because currently rust-url is not compatible with windows paths

src/hello_world.rs:2:9: 2:10 warning: unused variable: `x`, #[warn(unused_variable)] on by default
src/hello_world.rs:2 let x: int;
^
```

Rust warns us that we never use the variable binding, but since we never use it,
Expand All @@ -496,16 +496,16 @@ And try to build it. You'll get an error:

```{bash}
$ cargo build
Compiling guessing_game v0.1.0 (file:/home/you/projects/guessing_game)
src/guessing_game.rs:4:39: 4:40 error: use of possibly uninitialized variable: `x`
src/guessing_game.rs:4 println!("The value of x is: {}", x);
^
Compiling hello_world v0.1.0 (file:/home/you/projects/hello_world)
src/hello_world.rs:4:39: 4:40 error: use of possibly uninitialized variable: `x`
src/hello_world.rs:4 println!("The value of x is: {}", x);
^
note: in expansion of format_args!
<std macros>:2:23: 2:77 note: expansion site
<std macros>:1:1: 3:2 note: in expansion of println!
src/guessing_game.rs:4:5: 4:42 note: expansion site
src/hello_world.rs:4:5: 4:42 note: expansion site
error: aborting due to previous error
Could not execute process `rustc src/guessing_game.rs --crate-type bin --out-dir /home/you/projects/guessing_game/target -L /home/you/projects/guessing_game/target -L /home/you/projects/guessing_game/target/deps` (status=101)
Could not execute process `rustc src/hello_world.rs --crate-type bin --out-dir /home/you/projects/hello_world/target -L /home/you/projects/hello_world/target -L /home/you/projects/hello_world/target/deps` (status=101)
```

Rust will not let us use a value that has not been initialized. So why let us
Expand Down