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digitalmars.D.learn - classes allocated on the stack

reply "Steven Schveighoffer" <schveiguy yahoo.com> writes:
Regarding this documentation 
(http://www.digitalmars.com/d/1.0/memory.html#stackclass):

<quote>
Class instances are normally allocated on the garbage collected heap. 
However, if they:

    * are allocated as local symbols in a function
    * are allocated using new
    * use new with no arguments
    * have the scope storage class

then they are allocated on the stack.
</quote>

Why does rule 3 exist?  If I have a class:

class X
{
    private int n;
    this()
    { n = 5; }

    this(int x)
    { initialize(x); }

    initialize(int x)
    { n = x; }
}

And I want to allocate an instance on the stack, with n initialized to 3:

scope x = new X; // allocated on stack
x.initialize(3);
scope x2 = new X(3); // allocated on heap?

What about using the constructor with parameters makes it not possible to 
store on the stack?

-Steve
Apr 24 2008
parent reply Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:
Steven Schveighoffer wrote:

     * use new with no arguments




 Why does rule 3 exist?  If I have a class:




 
 What about using the constructor with parameters makes it not possible to 
 store on the stack?



"New with arguments" != "constructor with parameters". I think you 
missed this part of the spec: 
<http://www.digitalmars.com/d/1.0/class.html#ClassAllocator>
Apr 24 2008
parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
"Frits van Bommel" wrote

 Steven Schveighoffer wrote:

     * use new with no arguments




 Why does rule 3 exist?  If I have a class:




 What about using the constructor with parameters makes it not possible to 
 store on the stack?



 "New with arguments" != "constructor with parameters". I think you missed 
 this part of the spec: 
 <http://www.digitalmars.com/d/1.0/class.html#ClassAllocator>



Ah yes, I hadn't thought of it meaning that.  Another case of the example 
not being explicit enough :)  It would be nice if the counter example (with 
an example of new with arguments) was listed.  I'll post an enhancement 
report.

Thanks!

-Steve
Apr 24 2008