On 2015-05-12 7:57 PM, Karl Tomlinson wrote:
Ehsan Akhgari writes:
On Monday, May 11, 2015, Xidorn Quan <quanxunz...@gmail.com> wrote:
On Tue, May 12, 2015 at 7:29 AM, Ehsan Akhgari <ehsan.akhg...@gmail.com
<javascript:_e(%7B%7D,'cvml','ehsan.akhg...@gmail.com');>> wrote:
On 2015-04-30 7:57 AM, Xidorn Quan wrote:
I guess we probably should forbid using any expression with side effect
for
member initializers.
Hmm, why should we restrict them more than what can appear in the
constructor initializer list
Because it seems to me that, the member initializers are more obscure for
their initializing order. Given they can be disperced widely in different
places, it would be far harder to reason out the correctness from a piece
of code if the initializers could have side effect.
That's a good point! But I think expressions with side effects doesn't
really narrow down the issue. It's more an expression that can affect what
other expressions in the initializer list get evaluated to. And even that
issue is not specific to C++11 member initializers, the old school ones are
similarly affected (and in fact the initialization order is exactly the
same, based on the order of declarations, bases first.) but at least with
those you will get a compiler warning if you mistype the initialization
order in the body of the constructor... In short, I still don't see an
issue that is specific to C++11 member initializers.
I think it is not so much the order or initialization or
dependencies on other members that is different here but the fact
that member initializers may be dispersed in different parts of
the code, well away from the constructors, where one would usually
look for initialization side effects.
This is actually a great point!
I assume one could argue that the constructors of member variables
may have side effects and that code is not near the owning classes
constructor. However, member variable constructors do not have
access to private data or methods in the owning class. I assume
member initializers do have this access.
Yes, they do.
I expect things will be clearest if member initializers are used
only for effects on the associated member.
Yeah, I agree!
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