If the variable is null or not assigned, putting value in function does not work-CodePudding

I have this function that sometimes does not assign the variable $infolasterroredu

In these cases I want to tell the function to assign the value "Hello" if the variable is not assigned or is null.

I tried this way but it keeps returning the value "null" when the variable is not assigned.

How would I put a default value? I've tried all the options and nothing seems to work.

private static function stockstatus(Product $product, $infolasterroredu = 'Hello')
{
//my function code
}

The result of this code is null when debugging, what am I doing wrong?

I call the function like this self::stockstatus($product, $infolasterroredu);

I know this can be solved this way self::stockstatus($product, $infolasterroredu ?: "Hello");

But this would take editing all the function calls which are several so I need to do it by direct function.

Note: When I say direct function, it means directly putting the value in the private static function and not editing the calls to the function line by line, which are too many.

CodePudding user response：

By not having a type at all on the second argument, you're saying anything can be passed, but if nothing is passed (not even null), it's Hello. First, I would restrict the type if possible:

function stockstatus(Product $product, string $infolasterroredu = 'Hello') {}

This doesn't solve if '' (empty string) is passed in. You could "solve" this problem with a call-side default that passes in Hello if not present:

stockstatus($product, $infolasterroredu ?: 'Hello')

The problem I see with this is that it gives an internal concern for the function to some other caller, which makes the call more brittle in case the function itself changes.

Instead, I would set it up to allow a null switch but require a string, and default internally:

function stockstatus(Product $product, ?string $infolasterroredu = null) {
    $infolasterroredu = $infolasterroredu ?: 'Hello';

    ...
}

I'm using ?: to catch any empty or nulled value and default it to Hello. You can put 'Hello' in the default in the argument expression (this may help with type assist). However, I prefer to have someone read the function if they don't know how to call it, and I'm not duplicating the actual default value twice (in the argument default and in the internal check).

One downside, if you will, is that this accepts any truthy string, even, say or .. The best practice way of handling this is to use a value object with validation on the setter (or even a default non-thrown exception) as the second argument.

CodePudding user response：

Most probably, you pass two variable names as parameters when you call. You shouldn't put 2nd argument at all. stockstatus($productInput)

You can check if the second argument is null or not before calling the function. If you call with second parameter stockstatus($productInput, $somethingNull), it would overwrite the default value even if it's null.

CodePudding user response：

There are actually some ways you could do this.

First of all, just check before calling and create your default value before:

if (!$infolasterroredu) {
  $infolasterroredu = 'Hello'
}
self::stockstatus($product, $infolasterroredu);

But whenever you call the function in different places this might not be what you want.

Second way is to check for the value inside the function. So kinda the same functionality as before only you move this inside the function 'stockstatus'.

The third way is the way you want to do it. By giving a default value in the parameter. As other already pointed out, you need to call the function with only one parameter, only then PHP will fill in the default value for the missing parameters.

I would suggest the second way though.