Re: Overloading of operators '==' and '!='

--- Johannes Plass <[email protected]> wrote:
> Hi all,
> 
> being a PerlQt noob I would like to send a big
> "Thank You for this wonderful software" to the
> PerlQt developers, maintainers, supporters and
> documentation writers (did I miss someone ?).
> This is really a tool that saves me about
> 48 hours a day .....
> 
> Enough praising, here's a tiny recommendation
> I would like to throw into the discussion pool:
> 
> In PerlQt the copy constructor ('=') isn't overloaded
> since "it clashes with the perl paradigm" (as stated
> in the Changelog of 3.006).
> Now, for the same reason, I'd like to recommend to
> drop the overloading of operators '==' and '!='.
> The operators as they act now cause a loss of
> the object's identity based on reference comparison.
> 
> Example:
> Create a subclass MyPoint of Qt::Point, then construct
> lots of MyPoint objects and stuff them in a list.
> Now you're in trouble when you want to find
> a specific object in this list (for instance in order
> to remove it), since code like
>      if ($list[$i] == $mypoint) ...
> doesn't check the identity of the references but the
> equalness of the objects x and y coordinates.

Well.... perhaps the "correct" (semantically, not logically) way to do
this should be documented somewhere?

if($list[$i] eq $mypoint) { ...

Depending on the ref-stringification is unsightly, but it works.

My sincere apologies for the non-DWIM behavior of object comparison.
Perl needs an "is" operator or something. :)

Ashley Winters



	
		
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