[PATCH] Add configure flag for operator new (std::nothrow)

Sebastian Huber sebastian.huber@embedded-brains.de
Tue Nov 17 12:38:00 GMT 2015



On 05/11/15 16:22, Daniel Gutson wrote:
> On Wed, Nov 4, 2015 at 3:20 AM, Jonathan Wakely<jwakely.gcc@gmail.com>  wrote:
>> >On 4 November 2015 at 02:11, Daniel Gutson wrote:
>>> >>Since this is a nothrow new, we thought that probably the system
>>> >>might not be exceptions-friendly (such as certain embedded systems),
>>> >>so we wanted to provide the new_handler the ability to do something else
>>> >>other than trying to allocate memory and keep the function iterating.
>> >
>> >That could be done using an alternative overload of operator new
>> >instead of altering the semantics of the standard one (that could be
>> >provided as a GNU extension, for example).
>> >
>>> >>In fact, our idea is that since the nothrow new can indeed return nullptr,
>>> >>let the new_handler do something else and leave the no-memory-consequence
>>> >>to the caller.
>>> >>This new flag enables just that.
>> >
>> >
>> >The default configuration already allows the caller to deal with
>> >allocation failure from the nothrow version of new, by not installing
>> >a new-handler installed, and dealing with a null return value. How
>> >would I use this alternative configuration? Since the behaviour only
>> >changes when a new-handler is installed, presumably I'm meant to
>> >install some kind of new-handler that does something else ... but
>> >what? The patch should include documentation explaining when and how
>> >to use this option.
> Real use cases: statistics and logging. It's a (one time) callback
> reporting that something went wrong,
> but not intended to fix things e.g. by attempting to free more memory.

For statistics and logging you may also use the --wrap option of GNU ld.

-- 
Sebastian Huber, embedded brains GmbH

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