Carefully formatted columns (matrix literal example)

[anderejd]

Here's one interesting really bad case I just found:

             self.projection_matrix = Matrix4::new(
-                1.0/r, 0.0,   0.0,         0.0,   // NOTE: first column!
-                0.0,   1.0/t, 0.0,         0.0,   // 2nd
-                0.0,   0.0,   2.0/(n-f),   0.0,   // 3rd
-                0.0,   0.0,   (f+n)/(n-f), 1.0    // 4th
+                1.0 / r,
+                0.0,
+                0.0,
+                0.0, // NOTE: first column!
+                0.0,
+                1.0 / t,
+                0.0,
+                0.0, // 2nd
+                0.0,
+                0.0,
+                2.0 / (n - f),
+                0.0, // 3rd
+                0.0,
+                0.0,
+                (f + n) / (n - f),
+                1.0, // 4th
             );

Would it be possible to avoid breaking the formatting on a few select blocks? Maybe by some magic comment or by looking for lines that end with comments like this example?

[anderejd]

Would it make sense to never reformat lines that both ends with a // comment and has non-space characters before the comment starts?

If no, would a config option to activate that behavior be ok?

[anderejd]

For anyone like me, not always reading the manual properly for your tools, see this workaround:
https://github.com/rust-lang-nursery/rustfmt/blob/af3c3c694b842e047128e870f9bc8d56c7057c59/README.md#tips #[cfg_attr(rustfmt, rustfmt::skip)]

[nrc]

#[rustfmt::skip] has been stabilised. It works on nightly and will be riding the trains to stable.

[anderejd]

will be riding the trains to stable.

Got a guess on ETA?

[topecongiro]

P-low because this is a good target for rustfmt::skip. In the long run, rustfmt may be able to use the position of comment to figure out the optimal layout (this is not guaranteed to happen, as in general we try to avoid relying on user's input).

[nilgoyette]

Thank you, this is now fixed with #[rustfmt::skip].

However, I have a follow-up question concerning this "matrix" problem. We have dozens of matrix declarations in our project. Adding #[rustfmt::skip] does work, but I must add a lof of #[rustfmt::skip] in several files. Is there a tool to ask to skip the formatting for a list of objects in the whole project or for a folder? Something like

#[rustfmt::skip(Matrix3, Matrix4)]

in lib.rs or in a mod.rs?

[topecongiro]

@nilgoyette If you want to skip formatting the entire module, you can add #[rustfmt::skip] on mod foo; or add #![rustfmt::skip] in mod.rs of that module.

Alternatively you can use ignore configuration option.

[nilgoyette]

Thank you for the information, it might serve someday. It's not really what I'm asking though. It's more: skiping on a per-struct basis.

[anderejd]

Is it solved now?

[nilgoyette]

@anderejd Reading your original question "Maybe by some magic comment [...]", yes, this is solved. You can use skip like this:

#[rustfmt::skip]
let m = Matrix3::new(
    1.0, 0.5, 0.0,
    0.0, 1.0, 0.5,
    0.0, 0.5, 1.0,
);

and rustfmt won't touch anything until the line finishes, so the last ). You can also skip the formatting for an entire module. Sadly, there's no way to skip the formatting for all [Matrix3, Matrix4, ...] in a project though.

[anderejd]

IMHO it's not fixed, but I am thankful for the workaround.