#39: Add color to varify deps status results

[ffranr]

No description provided.

[dpc]

Concept OK, but colored won't work on windows. Also, it will print ascii garbage when users pipe the outputs to file etc.

We should use term crate, which is much more pain to use, because it can't abstract thing away as Strings, but that's because on windows colors are drawn by calling some kernel APIs, and not using ansi escape strings etc.

You can use https://github.com/slog-rs/term/blob/master/src/lib.rs#L1380 as a reference on how to use term.

You should probably implement something like this:

impl VerificationStatus {
 fn write_colored_to_stdout(&self) -> io::Result<()> { ... }
 fn write_colored_to_stderr(&self) -> io::Result<()> { ... }
}

Inside each of them, detect if the given output is a terminal (isatty) and if it is, use term calls to set and reset the color.

[ffranr]

Thanks for the feedback! I'll take a look at term.

[ffranr]

@dpc Is this the sort of thing you were thinking of?
I've used term.supports_color(). Do you think that I need to query isatty from libc also?

[dpc]

I have landed (that's my philosophy), but there are problems:

See cargo crev verify deps | less. The output is corrupted because we need to use something like https://docs.rs/atty/0.2.11/atty/ to detect if the output is actually an interactive terminal that supports colors. term.supports_color() must be checking something else. I'm guessing if$TERM variable supports color?

Some other improvements:

There will be more stuff to output in color.

We should probably have an API like this:

trait Colorizable { // or some better name
   fn color(&self) -> SomeTypeForColor;
}

and then some generic function/struct that checks term.supports_color() and atty and given an argument of type T : Colorizable + Display outputs it on stderr or stdout. The checks should probably be cached (I'm not sure how expensive they are).

@rffrancon Thank you for this PR, and let me know if you plan to work on the above, or should I look into it eventually, when I find a time.

[dpc]

I'm going to take a quick stab at it.

[ffranr]

@dpc Thank you for the feedback once more! I see that you've pushed this much further than what I had in mind, looks great. :)