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digitalmars.D - bug in purity validation

reply Timon Gehr <timon.gehr gmx.ch> writes:
From bearophile's ported benchmark:

    // Getters/Setters
    pure nothrow SimpleLoop* parent() { return parent_; }
    //...
    pure nothrow void setParent(SimpleLoop* parent) {
        parent_ = parent;
        parent.addChildLoop(&this);
    }
    //...
    SimpleLoop* parent_;

Why does that compile? There is no way those functions can be pure.

Timon
Jun 05 2011
parent reply Timon Gehr <timon.gehr gmx.ch> writes:
Timon Gehr wrote:

 From bearophile's ported benchmark:

     // Getters/Setters
     pure nothrow SimpleLoop* parent() { return parent_; }
     //...
     pure nothrow void setParent(SimpleLoop* parent) {
         parent_ = parent;
         parent.addChildLoop(&this);
     }
     //...
     SimpleLoop* parent_;

 Why does that compile? There is no way those functions can be pure.

 Timon



Ah, the implicit "this" parameter...

Timon
Jun 05 2011
parent reply Stewart Gordon <smjg_1998 yahoo.com> writes:
On 05/06/2011 11:10, Timon Gehr wrote:
<snip>

 Ah, the implicit "this" parameter...



What's that to do with anything?

Stewart.
Jun 11 2011
parent Timon Gehr <timon.gehr gmx.ch> writes:
Stewart Gordon wrote:

 On 05/06/2011 11:10, Timon Gehr wrote:
 <snip>

 Ah, the implicit "this" parameter...



 What's that to do with anything?

 Stewart.



I weakly pure function may modify any memory location reachable by its (mutable)
parameters. What I didn't realize at first and late in the night is that
obviously
this also applies to the implicit 'this' parameter.


Timon
Jun 11 2011