kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxxxx>]

On 10/1/2014 3:08 PM, jp charras wrote:
> Le 01/10/2014 20:42, Daniel Dawid Majewski a écrit :
>> On 01.10.2014 16:25, Wayne Stambaugh wrote:
>>> They do.  It is automatically generated by the compiler just like the
>>> source code comment explains.  Unless you need some special copy
>>> semantics (not just a direct copy of every class member which is what
>>> the compiler will generate), you do not need to write your own copy
>>> constructor.
>> Ok, so where are nested following python methods ?:
>> Copy(MODULE self, MODULE src)
>> Copy(ZONE_CONTAINER self, ZONE_CONTAINER src)
>> How I could make ?:
>> Copy(TRACK self, TRACK src)
>> Copy(VIA self, VIA src)
> 
> Seems there is a mistake between a copy constructor and the Copy method
> which exists for some BOARD_ITEMS, but not all (because currently this
> method is not needed in C++ Kicad code for track/vias)
> 
> The Copy method copy only some values from an existing source to an
> existing target.
> 
> The default copy constructor creates a clone (a new item) of an item.
> This is very different.
> 
> I'll add a Copy method (mainly for python scripts) for tracks/vias soon.

Please don't unless there is no other solution.  There is no reason to
create a custom copy method when the default copy constructor is more
reliable.  I promise you someone will add another class member that they
will forget to add to the copy method.  We've been bit by this several
times in the past.  It's a poor design pattern that I do not want to
repeat.  The only time I can think of the use a custom copy constructor
is when dynamically allocated memory is involved.  Are we using copyctor
feature flag in SWIG when generating the C++ source files?  If not, then
an explicit copy constructor must be defined.  You can read about it
here http://www.swig.org/Doc1.3/SWIGPlus.html#SWIGPlus_nn7.  Let see if
we can get SWIG to do it for us before we travel down the bad design path.

> 
> For now, to create a clone of a track/via using the default copy
> constructor, try to use something like :
> newtrack=oldtrack.__class__(oldtrack)
> 
> (I am hoping it works, I am not experienced in Python language)
> 
>