The copy constructor and assignment operator are pretty basic to polymorphism and C++ Inheritance, Equality is a different issue.
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Cirilo Bernardo Sent: Friday, August 03, 2012 6:55 PM To: Lorenzo Marcantonio; Kicad Developers Subject: Re: [Kicad-developers] operator == on PCB_PLOT_PARAMS ----- Original Message ----- > From: Lorenzo Marcantonio <[email protected]> > To: Kicad Developers <[email protected]> > Cc: > Sent: Friday, August 3, 2012 8:45 PM > Subject: Re: [Kicad-developers] operator == on PCB_PLOT_PARAMS > > On Fri, Aug 03, 2012 at 12:39:52PM +0200, Lorenzo Marcantonio wrote: >> Why is the operator definition needed? If the semantic is a >> field-by-field > comparison, it should get a default, like for assigment (it doesn't, > tried > it:P) > > Oops found the answer... there is no default == operator in C++ :P:P > (strange, they got default = but not default ==) > > -- > Lorenzo Marcantonio > Logos Srl > It's very simple; for an '=' operator you only need to copy a known amount of memory to provide a default operator which is useful in almost 100% of cases. There is no such generalization possible for the equivalence operator if a parameter is anything more than a single CPU register. For example, consider the quaternion represented by a structure containing 4 floats. When you check for the equivalence of the quaternions you only need to check 3 of those floats; if the quaternions are not normalized then you cannot even directly compare the 3 values to determine if the quaternions are equivalent. In my experience this situation is extremely common so I am not surprised that there is no default '==' operator. - Cirilo _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
