# argwerk
[
](https://github.com/udoprog/argwerk)
[
](https://crates.io/crates/argwerk)
[
](https://docs.rs/argwerk)
[
](https://github.com/udoprog/argwerk/actions?query=branch%3Amain)
Define a simple command-line parser through a declarative macro.
This is **not** intended to be a complete command-line parser library.
Instead this can be used as an alternative quick-and-dirty approach that can
be cheaply incorporated into a tool.
For a more complete command-line parsing library, use [clap].
We provide:
* A dependency-free command-line parsing framework using declarative macros.
* A flexible mechanism for parsing.
* Formatting of decent looking help messages.
We *do not* provide:
* As-close-to correct line wrapping with wide unicode characters as possible
(see [textwrap]).
* Built-in complex command structures like subcommands (see the
[subcommands] example for how this can be accomplished).
For how to use, see the documentation of [argwerk::define] and
[argwerk::args].
## Usage
Initially when you're adding arguments to your program you can use
[argwerk::args]. This allows for easily parsing out a handful of optional
parameters.
> This example is available as `simple`:
> ```sh
> cargo run --example simple -- --limit 20
> ```
```rust
let args = argwerk::args! {
/// A simple tool.
"tool [-h]" {
help: bool,
limit: usize = 10,
}
/// The limit of the operation. (default: 10).
["-l" | "--limit", int] => {
limit = str::parse(&int)?;
}
/// Print this help.
["-h" | "--help"] => {
println!("{}", HELP);
help = true;
}
}?;
if args.help {
return Ok(());
}
dbg!(args);
```
After a while you might want to graduate to defining a *named* struct
containing the arguments. This can be useful if you want to pass the
arguments around.
> This example is available as `tour`:
> ```sh
> cargo run --example tour -- --help
> ```
```rust
use std::ffi::OsString;
argwerk::define! {
/// A command touring the capabilities of argwerk.
#[derive(Default)]
#[usage = "tour [-h]"]
struct Args {
help: bool,
#[required = "--file must be specified"]
file: String,
input: Option,
limit: usize = 10,
positional: Option<(String, Option)>,
raw: Option,
rest: Vec,
}
/// Prints the help.
///
/// This includes:
/// * All the available switches.
/// * All the available positional arguments.
/// * Whatever else the developer decided to put in here! We even support wrapping comments which are overly long.
["-h" | "--help"] => {
println!("{}", Args::help());
help = true;
}
/// Limit the number of things by (default: 10).
["--limit" | "-l", n] => {
limit = str::parse(&n)?;
}
/// Write to the file specified by .
["--file", path] if !file.is_some() => {
file = Some(path);
}
/// Read from the specified input.
["--input", #[option] path] => {
input = path;
}
/// A really long argument that exceeds usage limit and forces the documentation to wrap around with newlines.
["--really-really-really-long-argument", thing] => {
}
/// A raw argument that passes whatever was passed in from the operating system.
["--raw", #[os] arg] => {
raw = Some(arg);
}
/// Takes argument at and .
///
/// * This is an indented message. The first alphanumeric character determines the indentation to use.
[foo, #[option] bar, #[rest] args] if positional.is_none() => {
positional = Some((foo, bar));
rest = args;
}
}
// Note: we're using `parse` here instead of `args` since it works better
// with the example.
let args = Args::parse(vec!["--file", "foo.txt", "--input", "-"])?;
dbg!(args);
```
## Time and size compared to other projects
argwerk aims to be a lightweight dependency that is fast to compile. This is
how it stacks up to other projects in that regard.
The following summary was generated from the [projects found here].
| project | cold build (release) | rebuild* (release) | size (release) |
|------------|----------------------|--------------------|----------------|
| argh** | 5.142723s (4.849361s) | 416.9594ms (468.7003ms) | 297k (180k) |
| argwerk | 1.443709s (1.2971457s) | 403.0641ms (514.036ms) | 265k (185k) |
| clap*** | 11.9863223s (13.1338799s) | 551.407ms (807.8939ms) | 2188k (750k) |
> *: rebuild was triggered by adding a single newline to `main.rs`.
> **: argh `0.1.4` including 11 dependencies.
> ***: clap `3.0.0-beta.2` including 32 dependencies.
You can try and build it yourself with:
```sh
cargo run --manifest-path tools/builder/Cargo.toml
```
[projects found here]: https://github.com/udoprog/argwerk/tree/main/projects
[argwerk::define]: https://docs.rs/argwerk/0/argwerk/macro.define.html
[argwerk::args]: https://docs.rs/argwerk/0/argwerk/macro.args.html
[clap]: https://docs.rs/clap
[ok_or_else]: https://doc.rust-lang.org/std/option/enum.Option.html#method.ok_or_else
[OsString]: https://doc.rust-lang.org/std/ffi/struct.OsString.html
[textwrap]: https://docs.rs/textwrap/0.13.2/textwrap/#displayed-width-vs-byte-size
[subcommands]: https://github.com/udoprog/argwerk/blob/main/examples/subcommands.rs