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Date: Thu, 27 May 2021 18:23:48 +0100
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Subject: Re: [PHP-DEV] Consensus Gathering: is_initialized
From: rowan.collins@gmail.com (Rowan Tommins)

On 27/05/2021 17:13, Andreas Leathley wrote:
>
> How is "uninitialized" magic? It is a state of a class property in PHP
> that is currently being exposed via reflection


Apologies if my last message was a bit too hastily written, and may have 
come across as rude.

What I meant by it being "magic" is that it can't be represented by any 
value or type. A lot of the examples in this thread attempt to use 
"uninitialized" like it was an extra value for the variable, as though 
the type of the property was "int|null|uninitialized". But that can't be 
declared in the property's type, and I don't know if there's even a 
docblock convention for "note that this property might be deliberately 
uninitialized, when it is, that means this ...".

Since we now have union types, you can actually be a lot more explicit 
about the extra state, and use something like "int|false|null"; in 8.1, 
you'll also be able to use "int|SomeEnum|null". Since those are real 
types, with real values, no extra functions need to be added to the 
language, and everything feels a lot less "magic".


> I have seen quite a
> few places where it occurs - for example with setter injection in
> frameworks, as an alternative to setting a property in the constructor. 

Just to reiterate, the new function would *only* be useful if you were 
trying to distinguish the uninitialized state from a null value.

If you have a property which you *know* might not be provided, you 
already have "null" to represent that. For instance, a property that 
might hold an instance of LoggerInterface, but only if the user calls a 
setLogger method, can be declared as "?LoggerInterface $logger=null", 
and tested with "isset($this->logger)".


PS: A much sillier reason why I hate "uninitialized" is that I 
consistently misspell it as "unitialized" :P

-- 
Rowan Tommins
[IMSoP]