genja-core-derive

genja-core-derive provides the procedural macros used by genja-core.

Macros

• #[genja_task(...)] generates genja_core::task::TaskInfo and genja_core::task::Task from an inherent impl block.
• #[derive(DerefMacro)] generates std::ops::Deref for tuple wrappers.
• #[derive(DerefMutMacro)] generates std::ops::DerefMut for tuple wrappers.

Task Authoring

use genja_core::genja_task;
use genja_core::inventory::Host;
use genja_core::task::{
    HostTaskResult, TaskError, TaskRuntimeContext, TaskSuccess,
};

struct CheckTask;

#[genja_task(name = "check", connection_plugin_name = "ssh")]
impl CheckTask {
    async fn start_async(
        &self,
        _host: &Host,
        _context: &TaskRuntimeContext,
    ) -> Result<HostTaskResult, TaskError> {
        Ok(HostTaskResult::passed(TaskSuccess::new()))
    }
}

Deref Wrappers

DerefMacro and DerefMutMacro expect a tuple wrapper with the wrapped value in field 0 and a DerefTarget trait in scope.

use genja_core_derive::{DerefMacro, DerefMutMacro};

trait DerefTarget {
    type Target;
}

#[derive(DerefMacro, DerefMutMacro)]
struct Values(Vec<String>);

impl DerefTarget for Values {
    type Target = Vec<String>;
}

let mut values = Values(Vec::new());
values.push("one".to_string());

assert_eq!(values.as_slice(), ["one".to_string()]);

Limitations

The current supported contract does not include:

• generic task structs
• non-static borrowed task names such as name: &'a str
• subtasks stored as Option<Arc<dyn Task>> or Vec<Arc<dyn Task>>
• task trait aliases such as Arc<dyn CoreTask>
• unknown #[task(...)] helper attributes
• DerefMacro or DerefMutMacro on non-tuple-wrapper types
• DerefMacro without an in-scope DerefTarget trait