Subject: Re: [boost] [Fit]Â formal review starts today
From: Paul Fultz II (pfultz2_at_[hidden])
Date: 2016-03-04 19:09:09
On Friday, March 4, 2016 at 5:09:19 PM UTC-6, Steven Watanabe wrote:
> On 03/04/2016 10:37 AM, paul Fultz wrote:
> >>> - Different functions in the library do not
> >>> have a consistent interface for similar
> >>> variations:
> >>> - always/always_ref vs. capture/capture_forward/capture_decay vs
> >>> partial w/ std::ref.
> > `alway_ref should be just an implementation detail. The user can already
> > `always(std::ref(x)) if they want a reference. I only use this to try
> and save
> > `some template instantiations when I need to the
> > `pattern.
> If it's meant to be an implementation detail,
> then it shouldn't be documented. Also, how do
> you know that this optimization makes any difference?
> If it does make a difference, then wouldn't users
> want to take advantage of it too?
`always_ref` is used a lot throughout the library. For users of the
may not be used as often. Perhaps it would be better to leave it out for
and then I can added it later, if there is need for this in other libraries
> >>> 145: // Since we disable the error for 4579 on MSVC, which leaves the
> >> static
> >>> // member unitialized at runtime, it is, therefore, only safe to
> >>> use this
> >>> // class on types that are empty with constructors that have no
> >>> possible
> >>> // side effects.
> >>> Shouldn't it also be safe for types with trivial
> >>> default constructors, since then, zero-initialization
> >>> will do the right thing?
> >> That is probably another case as well.
> > Sorry this is wrong. The value is uninitialized. So its only valid when
> there is
> > no data members to initialize(ie is_empty<T>) and the constructors have
> > side effects(ie is_literal<T>). Since it is uninitialized you can't
> expect it
> > be zero-initialized either.
> Okay, I'm not familiar with this particular
> compiler bug. I was just making a wild guess
> based on [basic.start.init]:
> "Variables with static storage duration (3.7.1)
> or thread storage duration (3.7.2) shall be
> zero-initialized (8.5) before any other
> initialization takes place."
> In Christ,
> Steven Watanabe
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