Re: [ljc] Return types

From: user 7.
Sent on: Wednesday, February 13, 2013 10:27 AM
Hi Jon,

You make me cry.


If doStuff is actually returning something for runStuff to do something then that would be fine with me, no a null or void object is not something.

I would avoid the inclination to try for conciseness by cramming as much as you can into a space. You achieve conciseness through good generalization and simplification. Let your code breathe:


Believe me, you will need the space to make notes on why you are doing it this way and what the side-effects are.

// This changes the very nature of the universe

// I expect the universe to be very different now

This approach will not be safe if the state is shared with other threads as runStuff most likely relies upon the side-effects of doStuff. 

I would avoid unnecessarily adding boilerplate for little to no tangible benefit, don't do this:

public void doStuff() {
  return null;

Or this (unnecessarily, if you need to return early then you can use this, however, I would wager it is possible to normalize the control flow for all cases and this would be better):

public void doStuff() {

The other approach is to use immutable objects and return an object that represents the next state, which is much safer:


Or you could have run stuff that takes the next state as the parameter:


Oh look, back to the beginning... But without the void return!

My two cents.


On Wed, Feb 13, 2013 at 9:47 AM, Ged Byrne <[address removed]> wrote:
Hi Jon,

Satire aside, the JSR should be for the "result self pattern".

By default void methods should return self, so that they can be used in method chains as part of a fluent interface.



On 12 February[masked]:14, Jonathan McNealy <[address removed]> wrote:
Hi guys,

We've been debating this for a while here, and we can't decide between the following two development methodologies with respect to the return statement.

It's currently policy to write functions that don't return a value like this:

public Void doTask() {

  return null;

this is best because:
- everything should be an object (Integer instead of int, and so on)
- it's type-safe
- reflection is more consistent, as the primitive/object difference api is a pain
- allows multiple calls on one line (saving vertical space, e.g. return runStuff(doTask()))

however some of the newcomers to the company are rather dismissive of the benefits of Void, and insist of the following nasty and inconsistent way of doing it:

public void doTask() {


and some deviants even insist on removing the return statement:

public void doTask() {


I'm currently in the process of writing up a JSR to only support the Void/return null pattern, as it's clearly the most consistent and only having one way of doing something is the best approach, however I'm curious as to what the community thinks about the issue.

Please don't cheat by casting your vote more than once!

Kind regards


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