与需要清理的对象一起包装

Question

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'")
}

Answer 1

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().