Platify

Platify streamlines cross-platform Rust development by removing the boilerplate associated with #[cfg(...)] attributes.

Instead of cluttering your code with repetitive checks and manual dispatch logic, Platify allows you to define platform-specific behavior using a clean, declarative attribute syntax.

Features

• #[sys_function]: Automatically dispatches method calls to platform-specific implementations (e.g., fn run() -> fn run_impl()).
• #[sys_trait_function]: Applies platform configuration to methods within a trait definition.
• #[sys_struct]: Generates platform-specific type aliases (e.g., MyStruct -> MyStructLinux) and verifies trait implementations at compile time.
• #[platform_mod]: Declares modules backed by OS-specific files (e.g., linux.rs, windows.rs) with strict visibility control.
• Smart Logic: Supports explicit include and exclude lists.
• Group Keywords: Use helpers like posix (Linux + macOS) or all.

Installation

Add this to your Cargo.toml:

[dependencies]
platify = "0.3.0"

Or run:

cargo add platify

Usage

1. Platform-Dependent Functions (#[sys_function])

This macro generates a default method that delegates the call to a suffixed implementation (e.g., _impl). It automatically applies the correct #[cfg] guards based on your configuration.

use platify::sys_function;

struct SystemManager;

impl SystemManager {
    // 1. Available on ALL supported platforms (default).
    //    Delegates to `reboot_impl`.
    #[sys_function]
    pub fn reboot(&self) -> Result<(), String>;

    // 2. ONLY available on Linux.
    #[sys_function(include(linux))]
    pub fn update_kernel(&self);

    // 3. Available on Linux and macOS, but NOT on Windows.
    #[sys_function(exclude(windows))]
    pub fn posix_magic(&self);
}

// Implementation details (usually handled in separate files or cfg blocks)
impl SystemManager {
    fn reboot_impl(&self) -> Result<(), String> {
        println!("Rebooting...");
        Ok(())
    }

    #[cfg(target_os = "linux")]
    fn update_kernel_impl(&self) {
        println!("Updating Linux kernel...");
    }

    #[cfg(unix)]
    fn posix_magic_impl(&self) {
        println!("Doing POSIX magic...");
    }
}

2. Platform-Specific Struct Aliases & Checks (#[sys_struct])

This macro does two things:

1. Creates type aliases for platform-specific builds (e.g., HandleWindows).
2. Verifies that the struct implements specific traits (like Send or Sync) at compile time. This is crucial for FFI wrappers where thread-safety is easily accidentally broken.

use platify::sys_struct;

// 1. Generates `HandleWindows` alias on Windows.
// 2. Asserts at compile time that `Handle` implements `Send` and `Sync`.
//    This works even with generics!
#[sys_struct(include(windows), traits(Send, Sync))]
pub struct Handle<T> {
    handle: u64,
    _marker: std::marker::PhantomData<T>,
}

// Generated code roughly looks like:
//
// #[cfg(target_os = "windows")]
// pub type HandleWindows<T> = Handle<T>;
//
// #[cfg(target_os = "windows")]
// const _: () = { ... assert T: Send + Sync ... };

3. Trait Definitions (#[sys_trait_function])

Allows you to define methods in a trait that are only available on specific platforms.

use platify::sys_trait_function;

trait DesktopEnv {
    // This method will only exist in the trait definition on Linux
    #[sys_trait_function(include(linux))]
    fn get_wm_name(&self) -> String;
}

4. Platform-Dependent Modules (#[platform_mod])

Maps a logical module to a platform-specific file (e.g., mod driver maps to linux.rs or windows.rs).

Visibility Logic: This macro separates internal convenience from external access:

1. External: The specific module (e.g., linux) inherits the visibility you declared (pub), so users must import crate::linux::Device.
2. Internal: The logical alias (driver) is generated as private, ensuring your internal code remains generic while forcing external users to be explicit about platform dependencies.

// Expects src/linux.rs and src/windows.rs to exist.
#[platform_mod(include(linux, windows))]
pub mod driver;

// --- Internal Usage ---
// Inside this file, we use the generic private alias.
fn init() {
    let _ = driver::Device::new();
}

Consumer Usage (External Crate):

// Error: 'driver' is private.
// use my_crate::driver::Device;

// Correct: The platform module is public.
#[cfg(target_os = "linux")]
use my_crate::linux::Device;

Configuration Logic

You can control which platforms are targeted using include(...) and exclude(...).

How it is calculated

1. Start: If include is present, start with that set. If omitted, start with all.
2. Filter: Remove any platforms specified in exclude.
3. Result: The macro generates #[cfg(any(target_os = "..."))] for the remaining platforms.

Examples

• include(linux) → Only Linux.
• exclude(windows) → Linux + macOS.
• include(posix), exclude(macos) → Only Linux.

License

This project is licensed under the MIT License - see the LICENSE file for details.