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Date: Mon, 13 Sep 2021 17:26:14 +0100
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Subject: Re: [PHP-DEV] Class static initialization block
From: rowan.collins@gmail.com (Rowan Tommins)

Hi Mike,

I will leave others to discuss the use cases. It would be interesting if 
people could find the motivating use cases that led to support in C#, 
Java, and JS.


I just wanted to comment quickly on these few points, though:


On 13/09/2021 15:05, Mike Schinkel wrote:

> 1.) Use static analysis to recognize a class has an initialization functionality and thus provide lint-specific to best practices for static initialization.


Theoretically, a convention is enough for this, since PHP has no 
official static analyser. But certainly a built-in syntax is the 
strongest kind of convention, so point taken.


> 2.) Make the initialization function private.


I'm not sure how that would work: a private constructor means that it 
has to be explicitly called from within the same class, but a static 
initialiser would be called by the engine, before the class scope even 
existed.


> 3.) Override and/or change order of initialization of parent in child class.


Similarly, I'm not sure this makes sense: it would imply that static 
initialisers are inherited, and would be re-run every time a new 
sub-class was defined, rather than being run strictly once when the 
class is loaded. If the child class wants to re-use code in its static 
initialiser, it would make more sense to call a (protected) static 
method than to directly repeat the parent's initialiser block.


 From your link, it seems that C# restricts them much more than methods 
or constructors:


>  *
>
>     A static constructor doesn't take access modifiers or have parameters.
>
>  *
>
>     A class or struct can only have one static constructor.
>
>  *
>
>     Static constructors cannot be inherited or overloaded.
>
>  *
>
>     A static constructor cannot be called directly and is only meant
>     to be called by the common language runtime (CLR). It is invoked
>     automatically.
>

Apparently, the JS implementation does allow multiple static initialiser 
blocks in one class, which are simply processed in order. But JS classes 
are weird creations, implemented as a complex sugar on top of a 
classless object system, so may not be the best point of reference for 
PHP, whose object system much more closely resembles Java or C#.


Regards,

-- 
Rowan Tommins
[IMSoP]