always-assert

可恢复断言，受 SQLite 中 assert 函数的使用 启发。

use always_assert::never;

fn apply_transaction(&mut self, tx: Transaction) -> Result<(), TransactionAborted> {
    let delta = self.compute_delta(&tx);

    if never!(!self.check_internal_invariant(&delta)) {
        // Ok, something in this transaction messed up our internal state.
        // This really shouldn't be happening, and this signifies a bug.
        // Luckily, we can recover by just rejecting the transaction.
        return abort_transaction(tx);
    }
    self.commit(delta);
    Ok(())
}

lib.rs:

可恢复断言，受 SQLite 中 assert 函数的使用 启发。

never! 和 always! 在禁用 debug_assertions 时返回条件的实际值。

当断言失败终止比继续运行更糟糕时使用它们。

一个例子是一个关键应用程序，如数据库

use always_assert::never;

fn apply_transaction(&mut self, tx: Transaction) -> Result<(), TransactionAborted> {
    let delta = self.compute_delta(&tx);

    if never!(!self.check_internal_invariant(&delta)) {
        // Ok, something in this transaction messed up our internal state.
        // This really shouldn't be happening, and this signifies a bug.
        // Luckily, we can recover by just rejecting the transaction.
        return abort_transaction(tx);
    }
    self.commit(delta);
    Ok(())
}

另一个例子是普通应用程序中关于非关键功能的断言

use always_assert::never;

let english_message = "super app installed!"
let mut local_message = localize(english_message);
if never!(local_message.is_empty(), "missing localization for {}", english_message) {
    // We localized all the messages but this one slipper through the cracks?
    // Better to show the english one then than to fail outright;
    local_message = english_message;
}
println!("{}", local_message);