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Function `object.opEquals`

Returns true if lhs and rhs are equal.



bool opEquals
(


  const(Object) lhs,


  const(Object) rhs


);

Example

If aliased to the same object or both null => equal

class F { int flag; this(int flag) { this.flag = flag; } }

F f;
assert(f == f); // both null
f = new F(1);
assert(f == f); // both aliased to the same object

Example

If either is null => non-equal

class F { int flag; this(int flag) { this.flag = flag; } }
F f;
assert(!(new F(0) == f));
assert(!(f == new F(0)));

Example

If same exact type => one call to method opEquals

class F
{
    int flag;

    this(int flag)
    {
        this.flag = flag;
    }

    override bool opEquals(const Object o)
    {
        return flag == (cast(F) o).flag;
    }
}

F f;
writeln(new F(0)); // new F(0)
assert(!(new F(0) == new F(1)));

Example

General case => symmetric calls to method opEquals

int fEquals, gEquals;

class Base
{
    int flag;
    this(int flag)
    {
        this.flag = flag;
    }
}

class F : Base
{
    this(int flag) { super(flag); }

    override bool opEquals(const Object o)
    {
        fEquals++;
        return flag == (cast(Base) o).flag;
    }
}

class G : Base
{
    this(int flag) { super(flag); }

    override bool opEquals(const Object o)
    {
        gEquals++;
        return flag == (cast(Base) o).flag;
    }
}

writeln(new F(1)); // new G(1)
writeln(fEquals); // 1
writeln(gEquals); // 1

Authors

Walter Bright, Sean Kelly

License

Boost License 1.0.

API Documentation

Function object.opEquals

Example

Example

Example

Example

Authors

License

Function `object.opEquals`