feattle-core
This crate is the core implementation of the feature flags (called "feattles", for short).
Its main parts are the macro [feattles!
] together with the trait [Feattles
]. Please refer to
the main package - feattle
for more information.
Usage example
use ;
use NoPersistence;
// Declare the struct
feattles!
// Create a new instance (`NoPersistence` is just a mock for the persistence layer)
let my_feattles = new;
// Read values (note the use of `*`)
assert_eq!;
assert_eq!;
assert_eq!;
How it works
The macro will generate a struct with the given name and visibility modifier (assuming private
by default). The generated struct implements [Feattles
] and also exposes one method for each
feattle.
The methods created for each feattle allow reading their current value. For example, for a
feattle is_cool: bool
, there will be a method like
pub fn is_cool(&self) -> MappedRwLockReadGuard<bool>
. Note the use of
[parking_lot::MappedRwLockReadGuard
] because the interior of the struct is stored behind a RwLock
to
control concurrent access.
A feattle is created with the syntax $key: $type [= $default]
. You can use doc coments (
starting with ///
) to describe nicely what they do in your system. You can use any type that
implements [FeattleValue
] and optionally provide a default. If not provided, the default
will be created with Default::default()
.
Updating values
This crate only disposes of low-level methods to load current feattles with [Feattles::reload()
]
and update their values with [Feattles::update()
]. Please look for the crates
feattle-sync and
feattle-ui for higher-level functionalities.
Limitations
Due to some restrictions on how the macro is written, you can only use [feattles!
] once per
module. For example, the following does not compile:
use feattle_core::feattles;
feattles! { struct A { } }
feattles! { struct B { } }
You can work around this limitation by creating a sub-module and then re-exporting the generated
struct. Note the use of pub struct
in the second case.
use feattles;
feattles!
use B;
Optional features
- uuid: will add support for [
uuid::Uuid
].
License
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
See CONTRIBUTING.md.