From: Mike Nordell (tamlin@algonet.se)
Date: Sat Nov 30 2002 - 02:23:30 EST
William Lachance wrote:
> Hub: m_pFrame in xap_FrameImpl needs to be accessed by its child
> classes, so it can't just be set to private without giving the children
> some way of accessing it. I think setting it to protected is a good way
> of doing so.
I disagree, strongly. If you _really_ need to do this, keep the data private
but use the aquaintance idiom. For an example of this, have a look at
gr_Win32Graphics.h.
I said it before and I'll probably tell less experienced developers this
until I die - Data in a "real" class has but one access specification,
private. Data in just "data" classes or struct (e.g. a Rect) can have the
access specification "public". Data _never_ (never, ever) is protected. The
_only_ things that belongs in protected is member functions intended for
just subclasses to have access to.
Any "protected" data I consider a bug.
If you want rationales, feel free to search the archives (possibly paying
attention to comments by me or Joaquin) or check groups.google.com for e.g.
comp.lang.c++.moderated.
/Mike
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