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V语言连接数据库代码示例

V语言 一个集合了 Go 的简单和 Rust 的安全特性的新语言。

主要特性:

  • 快速编译(编译器只有 400kb,而且无第三方依赖)
  • 安全
  • C/C++ 转换

示例代码:

数据库访问:

struct User { /* ... */ }
struct Post { /* ... */ }
struct DB   { /* ... */ }

struct Repo <T> {
    db DB
}

fn new_repo<T>(db DB) Repo {
    return Repo<T>{db: db}
}

fn (r Repo) find_by_id(id int) T? { // `?` means the function returns an optional
    table_name := T.name // in this example getting the name of the type gives us the table name
    return r.db.query_one<T>('select * from $table_name where id = ?', id)
}

fn main() {
    db := new_db()
    users_repo := new_repo<User>(db)
    posts_repo := new_repo<Post>(db)
    user := users_repo.find_by_id(1) or {
        eprintln('User not found')
        return
    }
    post := posts_repo.find_by_id(1) or {
        eprintln('Post not found')
        return
    }
} 

网络开发:

struct Story {
    title string
}

// Fetches top HN stories in 8 coroutines 
fn main() {
    resp := http.get('https://hacker-news.firebaseio.com/v0/topstories.json')?
    ids := json.decode([]int, resp.body)?
    mut cursor := 0
    for _ in 0..8 {
        go fn() {
            for  {
                lock { // Without this lock the program will not compile 
                    if cursor >= ids.len {
                        break
                    }
                    id := ids[cursor]
                    cursor++
                }
                resp := http.get('https://hacker-news.firebaseio.com/v0/item/$id.json')? 
                story := json.decode(Story, resp.body)?
                println(story.title)
            }
        }()
    }
    runtime.wait() // Waits for all coroutines to finish 
} 

 

Rick ©2018