From: "Kroeger, Simon (ext)" <simon.kroeger.ext@...>
Date: 2006-06-22T16:48:29+09:00
Subject: Re: The difference between s=s+"a" ans s<< "a"

 

> From: Robert Klemme [mailto:shortcutter@googlemail.com] 
> Sent: Wednesday, June 21, 2006 11:04 PM
> 
> 2006/6/21, Simon Kr�ger <SimonKroeger@gmx.de>:
> > I think
> >   s = s + "a" #
> > or
> >   s += "a"
> >
> > should be the norm as long as you do not know that using it 
> will cause
> > you problems (really only performance problems come to my mind)
> 
> I use the rule exactly the other way round: usually use << unless that
> might cause problems.  There's a lot of code out there that does +=
> while all it wants to do is appending.  += is less efficient and with
> my C++ background << more looks like "append".

Well, if you realy know what you do and if 'that might cause problems' 
there is of course no problem with <<. '+= is less efficient' smells like
premature optimization.
 
> > you will get what you expect if you use +=
> 
> It depends on what you expect.  If methods are expected to get
> something that they append stuff to then the observed behavior is
> exactly what you expect and want.  :-)

Hmm, I (but that may be just me) wouldn't write a method that 'get 
something that they append stuff to'. I would write a method which will
return the stuff and let the caller append it to whatever he wishes.
(I like it a bit functional style and do not like side effects) 

> For example, if you write a method that should append info about the
> current instance to something then you should use << because then even
> an IO object can be passed and the code still works as expected.

Yes, if I would write such a method, yes. If appending is exactly the
operation I want, I use it. sure.
 
> As generally, you should know your tools and be knowing what 
> you do. :-)

That sums it up quite perfect.
 
> Kind regards
> 
> robert

cheers

Simon