----- 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
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