是D范围故障/成功/退出必要吗？ [英] Is D's scope failure/success/exit necessary?

问题描述

当使用有try / catch / finally的语言时，D的失败/成功/退出范围声明仍然有用吗？ D似乎没有终于可以解释为什么这些语句在D中使用。但像C＃这样的语言是有用的吗？我正在设计一种语言，所以如果我看到很多优点，我会添加它。

When using a language that has try/catch/finally, are D's failure/success/exit scope statements still useful? D doesn't seem to have finally which may explain why those statements are used in D. But with a language like C# is it useful? I am designing a language so if I see many pros I'll add it in.

推荐答案

（X）不是必要的，因为对于 c>不是必需的，只要如果和 goto 。

scope(X) isn't necessary in the same way that for isn't necessary provided you have if and goto.

这是我今天写的一些代码的例子： / p>

Here's a paraphrased example from some code I've been writing today:

sqlite3* db;
sqlite3_open("some.db", &db);
scope(exit) sqlite3_close(db);

sqlite3_stmt* stmt;
sqlite3_prepare_v2(db, "SELECT * FROM foo;", &stmt);
scope(exit) sqlite3_finalize(stmt);

// Lots of stuff...

scope(failure) rollback_to(current_state);
make_changes_with(stmt);

// More stuff...

return;

使用try / catch将此对比：

Contrast this to using try/catch:

sqlite3* db;
sqlite3_open("some.db", &db);
try
{
    sqlite3_stmt* stmt;
    sqlite3_prepare_v2(db, "SELECT * FROM foo;", &stmt);
    try
    {
        // Lots of stuff...
        try
        {
            make_changes_with(stmt);

            // More stuff...
        }
        catch( Exception e )
        {
            rollback_to(current_state);
            throw;
        }
    }
    finally
    {
        sqlite3_finalize(stmt);
    }
}
finally
{
    sqlite3_close(db);
}

代码已变成 spaghetti ，传播整个商店的错误恢复，并强制一个级别的缩进每个try块。在我看来，使用范围（X）的版本明显更易读，更容易理解。

The code has turned into spaghetti, spreading the error recovery all over the shop and forcing a level of indentation for every try block. The version using scope(X) is, in my opinion, significantly more readable and easier to understand.

这篇关于是D范围故障/成功/退出必要吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！