idempotent

问题 Applications send out emails to verify user accounts or reset a password. I believe the following is the way it should be and I am asking for references and implementations. If an application has to send out a link in an email to verify the user's address, according to my view, the link and the application's processing of the link should have the following characteristics: The link contains a nonce in the request URI ( http://host/path?nonce ). On following the link (GET), the user is

问题 What is an idempotent operation? 回答1: In computing, an idempotent operation is one that has no additional effect if it is called more than once with the same input parameters. For example, removing an item from a set can be considered an idempotent operation on the set. In mathematics, an idempotent operation is one where f(f(x)) = f(x) . For example, the abs() function is idempotent because abs(abs(x)) = abs(x) for all x . These slightly different definitions can be reconciled by considering