对于if / else检查，返回false

Question

Sometimes you need to check if something is set or not, then you perform an operation. Sometimes there are many of these checks and I hate the indentation that is causes.

To minimize the nesting, I always check the opposite and return and then continue on the same indentation.

For instance, say the following

if (user.isOwner)
{
    // Do some operation
    // Set a value $accepted to true or false

    if ($accepted)
    {
        // Do more operation
        // And so on
    }
}

Instead, I write the above code as

if ( ! user.isOwner) return;

// Do some operation
// Set a value $accepted to true or false

if ( ! $accepted) return;

// Do more operation
// And so on

Could this ever lead to any problem? The function above when called, is not expected to return any result (ie I call is as doThisForMe() ). My coding here is done in PHP and Javascript. I don't know if this question would be language dependent.

Answer 1

As long as you don't want to return something this looks fine to me. Otherwise you could use the one-liner if.

return (<statemen>) ? <handles true> : <handles false>;

I am not sure if it is working in PHP too, but it is surely working with javascript.

Answer 2

This is something that is usually quite useful when you try to minimise the indentation in your script files. There are generally no problems with it.

The only problem that could possibly arise is if you want to add an else block to your functions. With the former syntax, it'd be a simple addition of else to the end of it. If you're using return instead, that'd be impossible, and you'd have to convert it to the former syntax.

This applies to both PHP and JavaScript. It also applies to most languages that have a similar kind of syntax.

Answer 3

In the case of Javascript this should do no harm at all since javascript functions return undefined either way. (you writing return; or not)

For PHP I'm not really sure, but I can't imagine any problems right now.

But I would think of this as bad practice since indentation helps to see what's going on. If you have many of those checks in one function, maybe you should think about creating more, smaller functions instead of one big function, because this too, helps reading your code.

Answer 4

if-elseif-else statements stop doing comparisons as soon as it finds one that's true. if-if-if does every comparison. The first is more efficient.

In your case, or in cases where control will leave the method (exceptions), there is no difference between doing multiple if statements and doing if-elseif-else statements.

However, it's best practice to use if-elseif-else anyhow. Suppose you change your code such that you don't do a return in every if block. Then, to remain efficient, you'd also have to change to an if-elseif-else idiom. Having it be if-elseif-else from the beginning saves you edits in the future, and is clearer to people reading your code.

These days to write a program is not a big task whereas the maintainabililty of the code is the major requirement. Because of the the chaning world and there requirements, We are required to update or change the code time to time. Thus it is very much required to indent the code for better readability .