Alf
Wed Jul 23 17:39:36 CDT 2008
* Igor Tandetnik:
> Alf P. Steinbach <alfps@start.no> wrote:
>> * Kürþat:
>>> We generally access non-static class members from a static method by
>>> passing "this" to that static method and accessing non-static
>>> members over "this". My alternative is caching "this" into a static
>>> member and use that
>>> static member whenever you need to access non-static members. Is
>>> there anything bad about this solution?
>> First, if static member functions are called from non-static ones,
>> with the pointer updated to the "current" instance, it lets you
>> violate constness without knowing it.
>
> How would that happen? This doesn't compile:
>
> class C {
> C* pThis;
> public:
> // Can't covert from const C* to C*
> void f() const { pThis = this; }
> };
>
> I agree with other points, but I don't quite see how this particular
> issue could occur.
I apologize for usign "unclear" :-) quoted terminology, it was meant to be
inferred from context.
Here's the OP's code:
<code from OP>
class Foo
{
public:
static Foo * lpThis;
Foo ()
{
// Some initializations...
lpThis = this; // Last statement in the constructor...
}
static void doJob ()
{
// Now we can access all non-static members over static "lpThis"...
}
};
Foo * Foo::lpThis;
</code from OP>
Now all we have to do is to introduce a const non-static member function, and
call doJOb from that:
<revised code>
<code from OP>
class Foo
{
public:
static Foo * lpThis;
Foo ()
{
// Some initializations...
lpThis = this; // Last statement in the constructor...
}
void blah() const { doJob(); }
static void doJob ()
{
// Now we can access all non-static members over static "lpThis"...
lpThis -> modify modify modify;
}
};
Foo * Foo::lpThis;
int main()
{
Foo const o;
o.blah();
}
</code from OP>
Cheers, & hth.,
- Alf
--
A: Because it messes up the order in which people normally read text.
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A: Top-posting.
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