英文:
package with objects that need cleanup
问题
我正在尝试将我的数据库代码分组到一个子包中，这样可以封装我的数据库连接和所有的预处理语句。
我可以在包的init函数中创建数据库连接和语句，但是我需要在某个时候关闭它们。
在一个程序中，这些变量是在使用它们的代码中初始化的，我会使用defer db.Close()等方式，但是在这里该怎么做呢？
我希望不暴露包的全局变量（连接和语句），这样调用者就无法访问它们以关闭它们。有没有一种更优雅的方法来做到这一点？
我怀疑我可能有一个错误的范例在脑海中，我试图在一种没有对象的语言中创建对象（本质上就是这样）。如果是这样的话，我将非常感谢任何关于如何以Go的方式做到这一点的帮助。
package database
import (
"database/sql"
_ "github.com/lib/pq"
)
var db *sql.DB
var stmtSelectUser *sql.Stmt
func GetUser(email string) string {
var name string
stmtSelectUser.QueryRow(email).Scan(&name)
return name
}
func init() {
var e error
db, e = sql.Open("postgres", "host=localhost dbname=pictocat sslmode=disable")
stmtSelectUser, e = db.Prepare("select * from users where email='$1'")
}
英文:
I am trying to group my database code into a sub-package, which would sort of encapsulate my database connection and all my prepared statements.
I can create the database connection and the statements in the package's init function, but I need to close them at some point.
In a program, where these variables are initialized in the code that uses them I would use defer db.Close(), etc, but how to go about this here?
I would prefer not to expose the package's global variables (connection and statements) so that the caller could access them to close them. Is there a way to do it in a more elegant manner?
I suspect that I might have a wrong paradigm in mind, and I am trying to create objects (this is essentially what it is here) in a language that does not have them. If so then I would appreciate any help with how to do it go-way.
package database
import (
"database/sql"
_ "github.com/lib/pq"
)
var db *sql.DB
var stmtSelectUser *sql.Stmt
func GetUser(email string) string {
var name string
stmtSelectUser.QueryRow(email).Scan(&name)
return name
}
func init() {
var e error;
db, e = sql.Open("postgres", "host=localhost dbname=pictocat sslmode=disable")
stmtSelectUser, e = db.Prepare("select * from users where email='$1'")
}
答案1
得分: 0
从你的示例代码中并不清楚你的问题是什么，但一般来说：
要么运行语句的函数需要完成语句并关闭它，要么你需要在你的包中添加一个函数，以便调用者可以关闭它；就是这么简单。
你不需要在你的包中暴露所有的数据库内容，只需要一个函数，该函数再调用Close()。
英文:
It's not really clear from your example code what your problem is, but in general:
Either the function running a statement needs to finish the statement and Close() it or you need to add a function to your package so the caller can close it; it's as simple as that.
You don't need to expose all of the database stuff in your package, just a function that in turns calls Close().
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