attribute-derive
Basicly clap for attribute macros:
```rust
[derive(Attribute)]
[attribute(ident = "collection")]
[attribute(invalid_field = "Error when an unsupported value is set (e.g. meaning=42")]
struct CollectionAttribute {
// Options are optional by default (will be set to None if not specified)
authority: Option,
#[attribute(missing = "Error when the value is not set")]
name: String,
// Any type implementing default can be flagged as default
// This will be set to Vec::default() when not specified
#[attribute(default)]
#[attribute(expected = "Error when an error occured while parsing")]
views: Vec,
// Booleans can be used without assiging a value. as a flag.
// If omitted they are set to false
some_flag
}
```
Will be able to parse an attribute like this:
```rust
[collection(authority="Some String", name = r#"Another string"#, views = [Option, ()])]
```
Limitations
There are some limitations in syntax parsing that will be lifted future releases.
- literals in top level (meaning something like
#[attr(42, 3.14, "hi")]
- function like arguments (something like
#[attr(view(a = "test"))]
- other syntaxes, maybe something like
key: value