[Issue 5931] keyword new won't allow default initialization of a struct where it has a non-zero argument constructor

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=5931


Christopher the Magnificent <ultimatemacfanatic at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|keyword new insists on      |keyword new won't allow
                   |calling a struct's          |default initialization of a
                   |(non-zero argument)         |struct where it has a
                   |constructor--in other       |non-zero argument
                   |words, it won't allow       |constructor
                   |default initialization;     |
                   |also postblit this(this)    |
                   |constructor dosen't get     |
                   |called from "new            |
                   |<structname>(<struct_instan |
                   |ce>)"                       |


--- Comment #3 from Christopher the Magnificent <ultimatemacfanatic at gmail.com> 2011-05-06 12:32:02 PDT ---
(In reply to comment #2)
> Post-blit is only called when you override the whole structure, as in:
> 
> ----------------------------------------
> import std.stdio;
> 
> struct S {
>     this(this) {
>         writeln("postblit");
>     }
> }
> 
> void main() {
>     S s;
>     S t;
>     s = t;    // <-- call postblit on s.
> }
> ----------------------------------------
> 
> Pointer-assignment will *not* call post-blit as you have not blitted
> (memcpy-ed) anything.


*Shouldn't* post-blit be invokable by calling <File(file)>?  Wouldn't this be a
desirable behavior?

If not, how do I allocate a default-initialized File struct in the heap using
<new>  (so that I can follow that by overwriting the whole structure and get
post-blitter to run)?

what I'm taking about is this (this is what I want to do):

////////////////////////////
import std.stdio;

struct Tokenizer
{
    File* file = null;

    void 
    initFile(File f)
    {
        this.file = new File;   // I want to allocate a new File struct and set
it to File.init -- DOESN"T WORK!
        *this.file = f;              // copy bits and then automatically call
post-blit File.this(this) 
    }
}
////////////////////////////

At the line above marked "DOESN'T WORK", the compiler refuses to allocate a new
default-initialized File struct.  This is a problem

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