Conference turris::c_plus_plus

3553.0. "Explanation needed for __init variable name" by CSC64::BLAYLOCK (If at first you doubt,doubt again.) Wed Apr 23 1997 19:58

This may be purely related to the use of an old compiler (V5.1)
but... (Digital UNIX V4.0a)

My customer has noticed that for the following .h file, if
the include lines are reversed, the name of the initializer
changes, for example (from odump -Ds)

the name __init_Foo40399160 changes to __init_Foo40399260

So, how is/was the name chosen?  I cannot produce this on more recent
compilers, has this changed (can this still occur for more complex
examples)?   The reason this is asked is that this is checked (the
executable) via differences against the odump output from different
builds, and these names tend to change for the simplist of things
(include order, added comments and such).

Thanks for any help.

---Foo.h---
#include <stream.h>
#include <stdio.h>

class Foo
{
public:
        Foo();
        ~Foo();

        void set(const int);
        void print();

private:
        int val;
};

---Foo.C---
#include "Foo.h"

Foo::Foo()
{
        val = 1;
}
Foo::~Foo()
{
}

void
Foo::set(const int new_val)
{
        val = new_val;
}

void
Foo::print()
{
        cout << "value: " << val << endl;
}
---ex1.C---
#include <stdio.h>
#include <stream.h>
#include "Foo.h"

main()
{
        Foo f;
        int i = 3;

        f.set(i);

        f.print();

        cout << "You fixed it!" << endl;

        return 0;
}

cxx -g -o foo Foo.C ex1.C

>So, how is/was the name chosen?

Its an internally generated number (actually, an address) that
cannot be counted on to be the same from one compilation to the
next.

Many thanks.  I presume that this naming convention still occurs in
later compiler releases?

I believe that the names chosen are less random in newer compilers.
That helps some test system things to work more easily.
Adding a line of code doesn't change all the subsequent lines and
changing compiler versions doesn't change the symbols names as much.
The new scheme may (I've not looked) number them starting at zero
or something like that...