Re: Why use object pointers rather than objects?
On Oct 16, 1:01 am, Erik Wikstr=F6m <Erik-wikst...@telia.com> wrote:
On 2007-10-16 00:46, Krishna wrote:
On Oct 15, 2:14 pm, Juha Nieminen <nos...@thanks.invalid> wrote:
krishna.kishore.0...@gmail.com wrote:
Why are always object pointers used? (i.e., ObjectType *objPointer)
Always? I don't always use them. In fact, I seldom use them.
This is a very typical example of where I don't use them:
std::string s = "hello";
No pointer there.
one advantage I see is passing them across methods, but is this pure=
ly
presentation issue (use 'objPointer' rather than '&obj') or are there
some performance affects?
If you pass an object by value then a copy will most probably be mad=
e,
which will often be less efficient than passing by reference or by
pointer. Also there's the slicing problem if inheritance is involved.
Thanks for the replies. When I was punching 'always' I was stuck in
the world of GUI, I see pointers being used for GUI objects, 'always'
That would probably be because GUI classes often makes heavy use of
polymorphism, (most graphical elements inherit from a base widget (or
whatever) class, and often implements a number of interfaces).
Independently of polymorphism (although that can also be a
reason), GUI classes often have identity. If you set the
background to red, you want it to be on the class instance which
controls the display, and not some copy. Classes which have
externally visible behavior often (usually?) have identity, and
when a class have identity, it can only be passed by reference
or by a pointer.
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