Re: In map iterator is there a difference between (*iter).second and iter->second?

From:

Joe Greer <jgreer@doubletake.com>

Newsgroups:

comp.lang.c++

Date:

Wed, 20 Aug 2008 13:45:24 +0000 (UTC)

Message-ID:

<Xns9B0063408FAEAjgreerdoubletakecom@85.214.90.236>

pjb@informatimago.com (Pascal J. Bourguignon) wrote in
news:7c7iacdnvb.fsf@pbourguignon.anevia.com:

Yes, but given a different class, they may be different:

#include <iostream>

class A {
public: int x;
};

class P {
public:
    A a1;
    A a2;

    A& operator*(){ return(a1); }
    A* operator->(){ return(&a2); }
};

using namespace std;

int main(void){
    P p;
    p.a1.x=1;
    p.a2.x=2;
    cout<<"p->x = "<<p->x<<" ; (*p).x = "<<(*p).x<<endl;
    return(0);
}

Sadly, this points out all the worst in operator overloading. operator
overloading is meant to allow user defined types to have the same semantics
as built-in types, not creative and unexpected usage such as this where the
reader of the code would be quite surprised to discover the difference. It
is much like defining operater + to add a1 + a1 wherease operator - adds a2
+ a2. Both legal, but definitely a bad idea from a maintenance POV. In
real life, code is maintened for years after the original author lost all
interest in it and it is best to code with those folks in mind.

joe