Re: Should I use an exception to pass an instance of my object?

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@gmail.com> 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/ZUtkn > > > V V sob., 24. okt. 2020 ob 20:11 je oseba Ashley Sheridan < > ash@ashleysheridan.co.uk> napisala: > >> >> >> On October 24, 2020 6:01:03 PM UTC, Jelly Legend <jelly.legend@gmail.com> >> 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@ashleysheridan.co.uk> napisala: >> > >> >> >> >> >> >> On October 24, 2020 9:13:44 AM UTC, Jelly Legend >> ><jelly.legend@gmail.com> >> >> 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 >> >