Color are now only used when outputting to a termainal/TTY. There are three new settings as well
which can be used to control color output, they are:
* `AppSettings::ColorAuto`: The default, and will only output color when outputting to a terminal or TTY
* `AppSettings::ColorAlways`: Outputs color no matter where the output is going
* `AppSettings::ColorNever`: Never colors output
This now allows one to use things like command line options, or environmental variables to turn
colored output on/off.
Closes#512
The `help` subcommand can now accept other subcommands as arguments to
display their help message. This is similar to how many other CLIs
already perform. For example:
```
$ myprog help mysubcmd
```
Would print the help message for `mysubcmd`. But even more, the `help`
subcommand accepts nested subcommands as well, i.e. a grandchild
subcommand such as
```
$ myprog help child grandchild
```
Would print the help message of `grandchild` where `grandchild` is a
subcommand of `child` and `child` is a subcommand of `myprog`.
Closes#416
Args and subcommands can now have their display order automatically
derived by using the setting `AppSettings::DeriveDisplayOrder` which
will display the args and subcommands in the order that they were
declared in, instead of alphabetical order which is the default.
Closes#444
Adds a setting for both `AppSettings` and an `Arg` method which allows
placing the help text for a particular argument (or all arguments via
the `AppSettings`) on the line after the argument itself and indented
once.
This is useful for when a single argument may have a very long
invocation flag, or many value names which throws off the alignment of
al other arguments. On a small terminal this can be terrible. Placing
the text on the line below the argument solves this issue. This is also
how many of the GNU utilities display their help strings for individual
arguments.
The final caes where this can be hepful is if the argument has a very
long or detailed and complex help string that will span multiple lines.
It can be visually more appealing and easier to read when those lines
don't wrap as frequently since there is more space on the next line.
Closes#427
External subcommands are now supported via the following:
```rust
extern crate clap;
use clap::{App, AppSettings};
fn main() {
// Assume there is a third party subcommand named myprog-subcmd
let m = App::new("myprog")
.setting(AppSettings::AllowExternalSubcommands)
.get_matches_from(vec![
"myprog", "subcmd", "--option", "value", "-fff", "--flag"
]);
// All trailing arguments will be stored under the subcommands sub-matches under a
// value of their runtime name (in this case "subcmd")
match m.subcommand() {
(external, Some(ext_m)) => {
let ext_args: Vec<&str> = ext_m.values_of(external).unwrap().collect();
assert_eq!(ext_args ,["--option", "value", "-fff", "--flag"]);
},
_ => unreachable!()
}
}
```
Closes#372
By using AppSettings::AllowLeadingHyphen values starting with a
leading hyphen (such as a negative number) are supported. This
setting should be used with caution as it silences certain
circumstances which would otherwise be an error (like forgetting
a value to an option argument).
Closes#385
