Scala for Data Science

Safer JDBC connections with the loan pattern

We have already seen how to connect to a JDBC database and send statements to the database for execution. This technique, however, is somewhat error prone: you have to remember to close statements; otherwise, you will quickly run out of memory. In more traditional imperative style, we write the following try-finally block around every connection:

// WARNING: poor Scala code
val connection = DriverManager.getConnection(url, user, password)
try {
  // do something with connection
}
finally {
  connection.close()
}

Scala, with first-class functions, provides us with an alternative: the loan pattern. We write a function that is responsible for opening the connection, loaning it to the client code to do something ...