Subject: Re: [std-proposals] Allow "default" keyword for default arguments
From: Daniel Gutson (danielgutson_at_[hidden])
Date: 2020-02-04 14:46:33
El mar., 4 de feb. de 2020 a la(s) 13:43, Edward Diener via Std-Proposals (
> My proposal is simply that whenever a template argument or a function
> argument has a default value the keyword "default" can be used to
> specify that value when instantiating a template or calling a function.
> The proverbial case for this is when a template or a function has more
> than one default value and the programmer wants to specify a value for a
> default while accepting other default values, whatever they may be. In
> this case I do not think it should be necessary for the programmer to
> know or care what the other default values are in order to set value(s)
> for particular defaults. By using the "default" keyword the programmer
> can do this more easily. In my proposal the use of the keyword "default"
> for a template or function argument which does not have a default value
> is a compiler error.
> I am aware of someone else's proposal along the same lines but I want to
> disassociate myself from that proposal completely, as it attempted to
> add a number of unnecessary and irrelevant provisos. My proposal is
> straightforward and is not intended to represent anything more
> complicated than what I have stated above.
> I have no idea whether this has ever been proposed officially to the C++
> standards committee, or what the outcome of such a proposal was, but if
> anybody does know I would be curious why the proposal was rejected. I am
> aware of workarounds to the issue which I intend to solve with this
> proposal, and I am aware of the attitude that the programmer should have
> to know and actively repeat a default value in order to specify
> arguments for further default values in positional arguments, but I see
> no reason why using the "default" keyword could not be used to make
> things easier for the programmer in this respect. Ease of language use
> should be important, especially when that ease incurs no great effort in
> implementation, which I believe my proposal entails.
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