class Base
{
 virtual DoThis() throw (domain_error) = 0;
 virtual DoThat() = 0;
};

class Derrived : public Base
{
 virtual DoThis() {}

 virtual DoThat(int* pValue) throw (invalid_argument)
 { if (pValue == NULL) throw invalid_argument("NULL Pointer"); }
};

Is the throw statement part of the signature needed for
inheritance?  Will both of these work?

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Michael S Scherotter <mss@tartus.com> writes:

> class Derived : public Base {
>  virtual DoThis();
        // overrides Base::DoThis()throw(domain_error)
>  virtual DoThat(int* pValue) throw (invalid_argument);
 // overrides Base::DoThat(int*), no throw clause

> Is the throw statement part of the signature needed for
> inheritance?

Yes, you can only restrict the set of exceptions a member function may
throw in it overriders or in its definition.

> Will both of these work?

No, the first one will not, because it says Derived::DoThis() can
throw any exception, but the base class promised to throw only
domain_error exceptions for this method.  The second declaration is
valid, since the base class could throw anything.

--
Alexandre Oliva
mailto:oliva@dcc.unicamp.br mailto:aoliva@acm.org
http://www.dcc.unicamp.br/~oliva
Universidade Estadual de Campinas, SP, Brasil
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