Re: Call constructor in another

From:

Salt_Peter <pj_hern@yahoo.com>

Newsgroups:

comp.lang.c++

Date:

29 Apr 2007 10:48:52 -0700

Message-ID:

<1177868932.446731.195320@o5g2000hsb.googlegroups.com>

On Apr 29, 10:02 am, terminator <farid.mehr...@gmail.com> wrote:

On Apr 28, 8:58 am, Blair Craft <lai...@square-enix.net.cn> wrote:

hi,

I got a class have 2 constructors:

static int g_idx_counter = 0;

[code]
Object::Object():{
   counter = g_idx_counter++;
   created_at = last_used = time(NULL);
   destroyed = false;
   id = -1;

}

Object::Object(int _id){
    Object();
    id = _id;}

[/code]

when I use:

  Object *o = new Object();

everything is OK, but when using the second constructor:

  Object *o = new Object(32);

member variable "counter" will remain untouched, I did a gdb trace,
Object::Object() was invoked and inside that function "counter" was
initialized, when function returns "counter" went back to 0
again. Behavior is like a local variable inside a code chunk, but here
counter is a class member variable, anyone can shed some light?

thanks

put shared instructions in a member function and call it in both
ctors:

void Object::build(){
    counter = g_idx_counter++;
    created_at = last_used = time(NULL);
    destroyed = false;
    id = -1;

};

Object::Object(){
    build();

};

Object::Object(const Object& ob){
    build();
    id=ob.id;

};

Thats a copy ctor. Assuming that Objects are indeed copyable, that may
not be what the OP wants.
There is nothing wrong with using a private member function as an
initializer otherwise.

Object::Object(int _id){
build();
id = _id;

}