[Development] Braces (was Re: Resolving coding style contentions)

[Thiago Macieira]

On Friday, 21 December 2018 04:59:34 -02 Alberto Mardegan wrote:
> Hi all!
>   Speaking of coding style again, I haven't found any indication in the
> coding guidelines about brace vs parentheses in initializations.

Because it wasn't a possibility before C++11.

I'd say we prefer assignment wherever possible, parens where it works, {} 
otherwise. Exception:
	 = {};

> There are a few cases where they can be used (and I might even be
> forgetting some):
> 
> 1) Constructors:
>        MyClass(): var(0) {}
>    vs
>        MyClass(): var { 0 } {}

Ugly -- and NSDMI looks better.

> 2) Member initializations:
>        class MyClass
>        {
>            int m_count = 3;
>    vs
>            int m_count { 3 };

Assignment looks better.

> 3) Variable initialization
>        bool ok = false;
>    vs
>        bool ok { false };

Ditto.

> 4) Constructor invocations:
>        auto *item = new Item("name", parent);
>    vs
>        auto *item = new Item { "name", parent };

Parens look better.

>    or
> 
>        QString message(QStringLiteral("text"));
>    vs
>        QString message { QStringLiteral("text") };
>    I guess this is not an option:
>        QString message { QStringLiteral { "text" } };

Parens look better. And QStringLiteral is a macro, so the third option just 
does not compile.

> I'm not mentioning the cases of struct and list initializers, where of
> course braces are the only option. But what is the consensus on the
> cases above?
> Looking at the Qt code, it seems that variant without braces is always
> preferred, but I cannot find it formalized anywhere.


-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center