Re: [scope] Proposing Boost.Scope

From: Darrell Wright (darrell.wright_at_[hidden])
Date: 2023-03-22 02:16:36

One thing I learned in my own replacement is that exit_success is heavily penalized on MSVC, even when there is no possible exception, because of the call to uncaught_exceptions that isn’t optimized.  It’s a good thing to document, if not already, as it is surprising.

Darrell

> On Mar 21, 2023, at 21:41, Andrey Semashev via Boost <boost_at_[hidden]> wrote:
> 
> Hi,
> 
> I'm proposing a Boost.Scope library for review and potential inclusion
> into Boost.
> 
> Boost.Scope is a small library implementing utilities defined in
> <experimental/scope> from C++ Extensions for Library Fundamentals v3
> with a few extensions. Namely, the library contains:
> 
> * A number of scope guards for various use cases.
> * A unique resource wrapper that automatically frees the resource on
> destruction.
> * Utilities for wrapping POSIX-like file descriptors in the unique
> resource wrapper.
> 
> Compared to <experimental/scope>, some notable extensions are:
> 
> * A new scope_final scope guard, which is a more lightweight alternative
> to scope_exit. It is accompanied with the BOOST_SCOPE_FINAL macro that
> allows to simplify scope guard declaration syntax.
> * Scope guards can be activated/deactivated multiple times.
> * Scope guards can be created inactive initially.
> * Scope guard factory functions, for compatibility with C++11.
> * Support for optional resource traits in unique_resource wrapper, which
> improves usage with resources having unallocated values.
> * unique_resource supports swapping.
> * unique_resource supports dereferencing for any resource types that
> support dereferencing, not only pointers.
> * More flexible constructors for unique_resource.
> 
> The library requires C++11 at the minimum and will significantly benefit
> from C++17.
> 
> Source:
> 
> https://github.com/Lastique/scope
> 
> Docs:
> 
> https://lastique.github.io/scope/libs/scope/doc/html/index.html
> 
> Current state: Feature complete, tested in the CI.
> 
> I'm asking for a review manager and endorsements.
> 
> I'm also looking forward for any pre-review comments. In particular, I'm
> interested in community opinion on the following:
> 
> * Is there interest in this library at all?
> * Should it be merged with Boost.ScopeExit, which is currently
> unmaintained? More on this below.
> * Should some/all of the library components be lifted to namespace
> boost? Such is the practice with most vocabulary types in Boost, e.g.
> boost::atomic, boost::shared_ptr, boost::any, boost::string_view, etc.
> Currently, the library defines its names in namespace boost::scope.
> * Comments on the resource traits feature are especially welcome.
> 
> Re. Boost.ScopeExit. There is significant functionality overlap with it
> in the scope guards department. The docs contain comparison with it. I
> believe there is room for both libraries because Boost.ScopeExit
> supports C++03 and Boost.Scope provides better syntax and more features,
> and both can be useful in their own regards, although I expect
> Boost.Scope to be more appealing in newer code bases. However, if the
> community decides there's too much overlap, I'm not opposed to merging
> the two libraries, although Boost.ScopeExit currently depends on
> Boost.Function, Boost.Preprocessor and Boost.TypeOf, which are
> unnecessary for Boost.Scope.
> 
> Thank you.
> 
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