`sol::table`: Checking for existance of key

[Kevin Brightwell]

Is there a means for checking for an existence of a key within a sol::table?

Additionally, when using sol::table::operator[], it returns a sol::proxy. However, this type has no means of checking the type of the underlying value.

Something like this might be neat:

sol::table tbl; // assume it's initialized
if (auto prox = tbl["my_key"])
{
  // use prox
}
else
{
  // prox doesn't actually exist
}

A method such as exists() would be useful, too. I took this syntax suggestion from boost's optional type.

[The Phantom Derpstorm]

sol::object x = tbl["my_key"];
if ( x != sol::nil ) {
// good to go
}
else {
// not good to go
}

[The Phantom Derpstorm]

I don't think we have an explicit exists function, though. It would be nice to add, you are right. I'll keep it in mind as I keep developing.

[Kevin Brightwell]

That's great! I knew I must be missing something. You already have an issue open for documentation, I guess this is a great case and point for it.

For exists(), it would be nice. Frankly, inlining that check seems like a pretty quick and dirty solution.

[Kevin Brightwell]

Correction, objects.hpp:

bool valid() const {
        return !this->is<nil_t>();
    }

[The Phantom Derpstorm]

I'll be sure to add it to the documentation. Right now I'm finishing the featureset necessary to get sol v2.0 off the ground (work is being done here).

[Kevin Brightwell]

Closing this as I've found the use cases. 👍