clap/examples/escaped_positional_derive.md
Ed Page befee6667b docs: Re-work examples
This creates distinct tutorial examples from complex feature examples
(more how-tos).  Both sets are getting builder / derive versions (at
least the critical ones).
2021-11-30 21:33:52 -06:00

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*Jump to [source](escaped_positional_derive.rs)*
You can use `--` to escape further arguments.
Let's see what this looks like in the help:
```bash
$ escaped_positional_derive --help
clap [..]
Kevin K. <kbknapp@gmail.com>, Clap Maintainers
A simple to use, efficient, and full-featured Command Line Argument Parser
USAGE:
escaped_positional_derive[EXE] [OPTIONS] [-- <SLOP>...]
ARGS:
<SLOP>...
OPTIONS:
-f
-h, --help Print help information
-p <PEAR>
-V, --version Print version information
```
Here is a baseline without any arguments:
```bash
$ escaped_positional_derive
-f used: false
-p's value: None
'slops' values: []
```
Notice that we can't pass positional arguments before `--`:
```bash
$ escaped_positional_derive foo bar
? failed
error: Found argument 'foo' which wasn't expected, or isn't valid in this context
USAGE:
escaped_positional_derive[EXE] [OPTIONS] [-- <SLOP>...]
For more information try --help
```
But you can after:
```bash
$ escaped_positional_derive -f -p=bob -- sloppy slop slop
-f used: true
-p's value: Some("bob")
'slops' values: ["sloppy", "slop", "slop"]
```
As mentioned, the parser will directly pass everything through:
```bash
$ escaped_positional_derive -- -f -p=bob sloppy slop slop
-f used: false
-p's value: None
'slops' values: ["-f", "-p=bob", "sloppy", "slop", "slop"]
```