Variadic grouping

[bearophile]

John Colvin:

> There are a mind-boggling large number of things that are 
> useful, but that's not the criteria for adding something to a 
> programming language.
>
> A new feature has to be *sufficiently* useful to justify the 
> increased complexity of the language and it's implementations 
> (plus not clashing badly with other features). Example use 
> cases are a useful way of demonstrating just how useful a 
> feature can be.

As example take a look at this commit, a small part of the 
changes to port the D front-end to D:
https://github.com/D-Programming-Language/dmd/compare/428e559e5f0b...68ab05dba14a

In this original line 'errors' is a boolean:
errors += global.endGagging(oldGaggedErrors);

It's replaced with:
if (global.endGagging(oldGaggedErrors))
     errors = true;

Looking at that code it's easy to think about code like this, 
that is not currently supported:

errors ||= global.endGagging(oldGaggedErrors);

Is the "||=" operator useful? Is it working well with the rest of 
the language? Is it easy to understand a read? It is not 
bug-prone given the existence of the "|=" operator? Even if all 
those answers are positive, you have to ask yourself if it's also 
sufficiently useful...

Bye,
bearophile