Considering this class:
class Matchable
{
protected:
class Match {
friend class Matchable;
void append( const Match& match ) {}
};
public:
virtual bool match( const Source& source ) = 0;
};
... where the outer class Matchable is a friend of the inner class Match, and considering this class:
class Literal : public Matchable {
bool match( const Source& source ) override {
Matchable::Match m;
Matchable::Match cm;
m.append( cm );
return true;
}
}
... where Literal is derived from Matchable, I seem to be able to instantiate Matchable::Match in Literal::match() without a problem, yet I am unable to call the private method Matchable::Match::append(), where I expected Literal to inherit the "friendliness" of Matchable.
Is this expected behavior and if so, is there a way to make Literal access private methods of its parent inner class Match?
Yes, this is expected behavior. See friend declaration
Friendship is not inherited (your friend's children are not your friends)
You might provide a delegate method in Matchable:
class Matchable
{
protected:
class Match {
friend class Matchable;
void append( const Match& match ) {}
};
void appendMatch( Match& match, const Match& matched ) {
match.append(matched);
}
public:
virtual bool match( const Source& source ) = 0;
};
then
class Literal : public Matchable {
bool match( const Source& source ) override {
Matchable::Match m;
Matchable::Match cm;
appendMatch(m, cm);
return true;
}
}
Otherwise you might make Match::append public (which make friend declaration meaningless).
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