I've come across the following constructor call syntax and although it
clearly is a problem, I couldn't find anything in the ARM that forbid
it.  I was wondering if the standard mentioned it.

   class MyClass {
   public:
      MyClass();
      MyClass(int x);
   };

   void foo() {
      MyClass x;

      x.MyClass(100);     <---- this is the strange ctor call
   }


My compiler (g++) doesn't complain about this.  When I tested this, I
found that "x.MyClass(100)" does indeed call the constructor with no
change in the "this" pointer -- effectively reconstructing the object,
although without destroying the previously constructed object (i.e.,
the one that was constructed with the default ctor).

Thanks,

/Woody

--
Woody Rowand
ADC Telecommunications - TSG         internet: wrowand@adc.com
2240 Campbell Creek Blvd.               voice: 972.680.7623
Richardson, TX 75082                      fax: 972.680.7672
---
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Woody Rowand wrote:
>
> I've come across the following constructor call syntax and although it
> clearly is a problem, I couldn't find anything in the ARM that forbid
> it.  I was wondering if the standard mentioned it.
>
>    class MyClass {
>    public:
>       MyClass();
>       MyClass(int x);
>    };
>
>    void foo() {
>       MyClass x;
>
>       x.MyClass(100);     <---- this is the strange ctor call
>    }
>
> My compiler (g++) doesn't complain about this.  When I tested this, I
> found that "x.MyClass(100)" does indeed call the constructor with no
> change in the "this" pointer -- effectively reconstructing the object,
> although without destroying the previously constructed object (i.e.,
> the one that was constructed with the default ctor).

As far as I know, it's not allowed in the standard, so it must be an extension
(of which G++ seems to have a few). The correct way to apply a constructor is
with the placement new syntax:

 new(&x) MyClass(100);

--

Ciao,
Paul
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