Add filter for non-repeatable fields

[JPry]

This also streamlines how the field type is checked. Using isset() is more efficient than in_array().

[jtsternberg]

I'm not sure I understand the value of reversing this to use array keys?

[JPry]

@jtsternberg

I'm not sure I understand the value of reversing this to use array keys?

Here's a StackOverflow answer that should explain it.

[jtsternberg]

I was familiar w/ the fact that isset is faster than in_array, but having a hard time believing the value gained from using array keys (for the number of items that would live in this array), is worth developer confusion w/ using this filter with array keys.
Convince me. ;)

[JPry]

@jtsternberg It's true that any single instance of this method being called won't produce any significant performance increase, and it may add some confusion. However, this method is called every single time an instance of CMB2_Field is created. There are 5 calls currently in CMB2, and a single call each in CMB2_Sanitize and CMB2_Types.

Taking into account multiple fields and multiple metaboxes, this very quickly increases by a significant factor. Thus, the performance improvement can add up and be worth the slight confusion developers may have.

[jtsternberg]

Color me convinced. Thank you for thinking this through.