Fw: [C++-sig] Pyste and STL types

[Nicodemus]

David Abrahams wrote:

>Nicodemus <nicodemus at globalite.com.br> writes:
>
>
>>What do you mean by "active field"? I ask because my knowledge of
>>unions is limited.
>>
>
>The one someone stored data in.
>

I know, but from your comment I understood that C/C++ took care of this 
for you, like this:

union Test
{
    float d;
    int i;
};

void main()
{
    Test t;
    t = 3.0;       // use the d member
    float x = t;  // get the d member
    t = 1;         // set the i member
    int z = t;     // get the i member
}

Which I don't think is the case. The programmer has to take care of what 
field is active:

void main()
{
    Test t;
    t.d = 3.0;     // set the d member
    int z = t.i;   // member i has garbage
    float x = t.d; // ok
}

What am I missing?