auto casting about json11 HOT 4 OPEN

I would definitely recommend defining the conversion functions as explicit (https://en.cppreference.com/w/cpp/language/cast_operator) to reduce the risk of the unexpected conversions mentioned above. Even so, I'm not sure this is something we'd want to merge in upstream - better to keep "down-casts" explicit.

from json11.

You want to make those const:

operator int() const {
            return int_value();
}

Or you compiler might decide some really strange casts in some cases where there are temporaries.

Next, I recommend against it, implicit casts to integer types (including bool) from objects is very easy to go wrong.

from json11.

Not had a problem so far - but thanks for that !

What do you mean by " implicit casts to integer types (including bool) from objects is very easy to go wrong." ? I've found that if you try to read the wrong type, you'll just get a zero.

from json11.

Well, compilers can decide to implicitly cast without you expecting it.

I think this example works unexpectedly, as both Foo instances are cast to bool in the if(), and then the compare is true.

class Foo
{
public:
    Foo(int n) : value(n) {}

    operator bool() const
    {
        return value != 0;
    }
private:
    int value;
};

Foo bar()
{
    return Foo(1);
}

void test()
{
    if (bar() == Foo(2)) { printf("True!\n"); }
}

You can have the same thing if you compare objects that are incompatible for comparison, or if the comparison operator isn't defined const while the casts are (at this example also includes a temporary)

from json11.