On Thu, May 16, 2013 at 1:02 PM, Maxim Fomin <[email protected]> wrote:
>
>
>
> 2013/5/16 Михаил Страшун <[email protected]>
>>
>> Wall of text incoming.
>>
>> First. I'd like to remind to several important properties of D structs:
>>
>> * They have both compile-time initialization and run-time one. First
>> is T.init, second is T(...). Needing both is a perfectly valid need
>> from the programmer, especially with generic code in question.
>
>
> T.init is statically known constant default value of a type and T(..)
> expression when applied to
> the struct can be a struct literal, constructor invocation or an opCall.
>
> Default value (T.init) is same both in compile time and runtime unless you
> deliberatly hack
> generated object file at runtime. But this has nothing to do with
> "compile-time initialization" and "runtime initialization".
You have just said the very same but in different words. What is
important that you need both "const x = ..." syntax to change T.init
and ability to change it in literal/constructor when struct is created
at run-time.
>> * structs always have constructors. So this snippet is wrong:
>> > struct S
>> > {
>> > immutable int c = 123; // This should be static, compiler issues
>> > error
>> > // No constructor
>> > }
>> In fact, S has constructor. All structs have constructor with
>> parameter count that matches member field count. And judging only by S
>> definition you can't ever possibly say if "c" will be the same in all
>> S instances or not.
>
>
> No. This S does not have a constructor. Expressions with "parameter count
> that mathces
> member field count" is struct literal and it has nothing to do with implicit
> constructor generation
> or calling any function. Please check things before you type.
Difference does not matter in this context (I apologize for bad
wording though). What I am saying, you can never say that immutable
field value will always stay the same even in absence of explicit
constructors. What you say does not contradict it.
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