classes in unions?

[uralmutlu]

Hi,

I was wandering if I can have classes in unions?

I basically have source code in a format very similar to:

union example {
ClassA variable1;
ClassB variable2;
};

class AnotherClass {
.....
example SomeName;
.....

};

However, the compiler (gcc) tells me constructors aren't allowed in
unions.

I have a very large program written for eg ClassA, and I am adding a
second class, eg ClassB, to it. I came to this particular code, and I
thought unions would be an easy solution, but it looks like I will have
to make other changes.

I thought since classes are types they would be allowed in unions.

so no classes in unions?

regrads

[Ian Collins]

ur*******@gmail .com wrote:

Hi,

I was wandering if I can have classes in unions?

I basically have source code in a format very similar to:

union example {
ClassA variable1;
ClassB variable2;
};

class AnotherClass {
.....
example SomeName;
.....

};

However, the compiler (gcc) tells me constructors aren't allowed in
unions.

I have a very large program written for eg ClassA, and I am adding a
second class, eg ClassB, to it. I came to this particular code, and I
thought unions would be an easy solution, but it looks like I will have
to make other changes.

I thought since classes are types they would be allowed in unions.

so no classes in unions?

Think about it - which constructor initialises the object?

Unions are rare in C++ (compared to C), C++ offers more appropriate
solutions. Unions are often used as a poor man's polymorphism in C.

--
Ian Collins.

[Frederick Gotham]

ur*******@gmail .com posted:

I was wandering if I can have classes in unions?

Yes, but each member of the union must be a POD.

--

Frederick Gotham

[loufoque]

ur*******@gmail .com wrote :

I was wandering if I can have classes in unions?

See boost.variant.

[Jim Langston]

<ur*******@gmai l.comwrote in message
news:11******** **************@ b28g2000cwb.goo glegroups.com.. .

Hi,

I was wandering if I can have classes in unions?

I basically have source code in a format very similar to:

union example {
ClassA variable1;
ClassB variable2;
};

class AnotherClass {
....
example SomeName;
....

};

However, the compiler (gcc) tells me constructors aren't allowed in
unions.

I have a very large program written for eg ClassA, and I am adding a
second class, eg ClassB, to it. I came to this particular code, and I
thought unions would be an easy solution, but it looks like I will have
to make other changes.

I thought since classes are types they would be allowed in unions.

so no classes in unions?

regrads

Instead of a union, I think polymorphism would work better for you.