Comments on: The Most Vexing Parse: How to Spot It and Fix It Quickly

By: Jonathan Boccara

Jonathan Boccara — Sun, 15 Jul 2018 21:33:00 +0000

In reply to Panos KJ. Yes absolutely, that's the more modern approach for the most vexing part. And uniform initialization is a horny topics with things to talk about indeed, thanks for the suggestion :)

By: Panos KJ

Panos KJ — Fri, 13 Jul 2018 09:35:00 +0000

My first though on how to fix this was KeyInstrument key{FutureDate(date1), OptionExpiry(date2)}; Or even KeyInstrument key{FutureDate{date1}, OptionExpiry{date2}}; You could write an article on always using uniform initialization.

By: Puneet Agrawal

Puneet Agrawal — Fri, 16 Feb 2018 10:43:00 +0000

Nice article Jonathan.
In addition to the above mentioned solutions, another solution one can also use in pre-C++11 systems, is to use old C-style cast or static_cast, which is more clear, as your are theoretically doing a casting here, though internally both are the same types.
e.g.
KeyInstrument key(static_cast(date1), static_cast(date2));
or
KeyInstrument key((FutureDate)date1, (OptionExpiry)date2);

By: Aymen Schehaider

Aymen Schehaider — Wed, 07 Feb 2018 10:53:00 +0000

Aha a nice post by the way. Hopefully we are using uniform initialization @work, but it is always good to know about vexing-parse 😀

By: Jonathan Boccara

Jonathan Boccara — Tue, 06 Feb 2018 20:59:00 +0000

In reply to David Forgeas. Haha you're right! I've included this remark into the post. Thanks

By: David Forgeas

David Forgeas — Mon, 05 Feb 2018 16:21:00 +0000

A a(B());
a is a function that takes a function pointer and returns an A by value. The function pointer, which is unnamed, points to a function that takes no arguments and returns a B by value. Right?

By: Jonathan Boccara

Jonathan Boccara — Fri, 02 Feb 2018 11:14:00 +0000

In reply to Richard Rombouts. You're right, I've replaced brackets with curly braces. Thanks Richard!

By: Richard Rombouts

Richard Rombouts — Fri, 02 Feb 2018 08:22:00 +0000

Great article. Except { and } are normally called (curly) braces and the round ( and ) are called (round) brackets.

… which consists in calling constructors with brackets {} instead … // <- curly braces
A function doesn’t declare its parameters with brackets, so there … // <- curly braces

A function ***does*** use (round) brackets!

By: Norbert Riedlin

Norbert Riedlin — Fri, 02 Feb 2018 06:30:00 +0000

Thanks for the article. One point to note is that the line
A a;
won’t zero initialize a, if A is a builtin type like int. Something you have to consider when writing templates. You should definitely use
A a {};
in such cases.

By: Nico Bako

Nico Bako — Thu, 01 Feb 2018 21:56:00 +0000

Wow! Thanks for the post. I always wondered why I would get errors when I did not omit the parentheses whenever I was instantiating an object that doesn't take any arguments in its constructor like A a(); . I just ran this code :


class A {
public:
	A(){}
	A(int){};
};

int main() {
	A a1();
	A a2(5);
}

and I was surprised that it compiled and ran. But, when I debugged it I noticed that object a2 existed on the stack, but object a1 did not... Very interesting!