• dtiktin (93/93) Jul 08 2004 I see there are some open issues about auto (such as order of

dtiktin <dtiktin nospam.totally-bogus.com> writes:

I see there are some open issues about auto (such as order of 
destruction), but I'm not sure if this is one of them.  The 
documentation says:

[quote]

When an auto class reference goes out of scope, the destructor (if 
any) for it is automatically called. This holds true even if the 
scope was exited via a thrown exception. 

[/quote]

Which is fine except that it seems to be true even if the constructor 
of the auto object itself throws an exception.  Here's some code 
typical of the RAII idiom which demonstrates the problem:

[code]

import std.c.stdio;
import std.c.stdlib;
import std.string;

auto class A
{
    this(int i)
    {
        if (i > 0)
        {
            throw new Exception("A ctor exception.");
        }
    }
    ~this()
    {
        printf("A dtor.\n");
    }
}

auto class B
{
    this(int i)
    {
        if (i <= 0)
        {
            throw new Exception("B ctor exception.");
        }
    }
    ~this()
    {
        printf("B dtor.\n");
    }
}

int
main(char[][] argv)
{
    int i = -1;

    if (argv.length > 1)
    {
        i = atoi(argv[1]);
    }

    try
    {
        printf("Creating A.\n");

        auto A a = new A(i);

        printf("A created.\n");

        printf("Creating B.\n");

        auto B b = new B(i);

        printf("B created.\n");
    }
    catch (Exception ex)
    {
        printf("%.*s\n", ex.toString());
    }
    finally
    {
        printf("finally.\n");
    }

    return (EXIT_SUCCESS);
}

[/code]

Run without an argument (using dmd 0.94) it prints:

Creating A.
A created.
Creating B.
A dtor.
B ctor exception.
finally.
B dtor.

I was happy until the last line.  Naively, I would think the 
destructor for B should not be run since the ctor did not finish.  

Run with an argument of 9 it prints:

Creating A.
A ctor exception.
finally.
A dtor.

Bug or no bug?

BTW, is there an official bug list?  (I found the pending peeves list 
on the wiki, but this doesn't seem to be an offical bug list.)

Dave

-- 
D.a.v.i.d T.i.k.t.i.n
t.i.k.t.i.n [at] a.d.v.a.n.c.e.d.r.e.l.a.y [dot] c.o.m