Yes, the __construct doesn't return anything if I throw an
exception. But I can pass the $this into the custom exception object and
thus still retrieve it from the caught exception.
Better example: https://3v4l.org/ZUtkn
V V ned., 25. okt. 2020 ob 09:32 je oseba Jelly Legend <jelly.legend@xxxxxxxxx> napisala:
Yes, the __construct doesn't return anything if I throw an exception. But I can pass the $this into the custom exception object and thus still retrieve it from the caught exception.Better example: https://3v4l.org/ZUtknV V sob., 24. okt. 2020 ob 20:11 je oseba Ashley Sheridan <ash@xxxxxxxxxxxxxxxxxxxx> napisala:
On October 24, 2020 6:01:03 PM UTC, Jelly Legend <jelly.legend@xxxxxxxxx> wrote:
>Thank you, the example I put was mostly just for showing that it is
>valid
>to return an instance of an object even though the constructor failed.
>I
>was thinking of implementing this for a ShoppingCart class where I load
>the
>products from the db to. I use the same public methods of the class to
>load
>the products and they contain validation. So it can happen that the
>cart
>from the db has more quantity than there is stock available but this
>information is known to me only after / in instantiation. I could
>validate
>the items beforehand but I wanted to avoid double looping since I don't
>consider stock change a valid enough reason, but I still need the
>information to notify the end user about the cart changes without some
>global hackery. I ended up implementing a didChange method that can be
>used
>to retrieve the information I was looking to pass through the
>exception.
>Although, it was an interesting thought, to use an exception in the
>constructor to pass the object itself back to the client code since the
>state of the object was not considered invalidated enough to stop
>execution
>but still invalid enough to notify the caller further action should be
>taken.
>
>V V sob., 24. okt. 2020 ob 13:59 je oseba Ashley Sheridan <
>ash@xxxxxxxxxxxxxxxxxxxx> napisala:
>
>>
>>
>> On October 24, 2020 9:13:44 AM UTC, Jelly Legend
><jelly.legend@xxxxxxxxx>
>> wrote:
>> >I'm facing a situation where I want to use an exception in my
>> >__construct
>> >method to notify the caller that the input data is invalid. But I
>> >because I
>> >want to avoid having to use a static constructor method or validate
>the
>> >data before the __construct call I thought I would just modify the
>data
>> >based on my needs and at the very end of __construct throw a custom
>> >exception what holds the instance of $this so it can still be used
>at
>> >the
>> >callers side.
>> >
>> >Example: https://3v4l.org/pbIWR
>> >
>> >Should I do it?
>>
>> Personally for these sorts of things I tend to do only very basic
>> validation in a constructor if it's ever needed, and directly throw
>an
>> exception there specific to the class the constructor is in. PHP can
>do all
>> the type checking for you (it's much better in PHP 7.1 and up) and
>you can
>> wrap calls to constructors in a try/catch block to handle them better
>and
>> give the user the error output you need them to have, whilst logging
>more
>> full information.
>> Thanks,
>> Ash
>>
Because of the throw, you're not actually returning an object. The exception is being thrown, and isn't caught by the class that's dynamically constructing the custom exception object. The only side effect is some extra memory used to hold that instance (although it will be a very small amount and likely the GC will clear it up very soon afterwards.)
Thanks,
Ash
