TemplateIterator does not share any APIs of NodeBinding

[jmesserly]

Not sure if this is a bug, or an intentional design tradeoff, but:

The NodeBinding type, typically accessible via Node.bindings has various APIs such as:

• node
• property
• mode
• path
• value - getter/setter

In contrast TemplateElement.bind returns a TemplateIterator. It does not have any of those properties. Indeed, it cannot, as the same instance is shared by if/bind/repeat. (Is that for performance reasons?).

A few issues here:

• what APIs are expected from Node.bindings?
• should there be a NodeBinding that is created seperately for if/bind/repeat and points at the TemplateIterator? It could implement NodeBinding correctly.
• alternatively, if it we must reuse TemplateIterator for performance, should I be able to use a type test to distinguish the two types of bindings? Currently NodeBinding and TemplateIterator names are both private (although the members are public via .bindings)
• what is public API on TemplateIterator? Many of the methods/properties don't look public (you could violate the class invariants by calling methods at unexpected times.) Here's my guess on the public surface area... based on what would be useful reflection:
  • hasRepeat/hasBind/hasIf
  • repeatModel/bindModel/ifModel
  • repeatPath/bindPath/ifPath
  • close()/closed

[jmesserly]

Another issue with this:

// Normally calling .close will only close that binding.
// However this will close the TemplateIterator, including the "bind" and "repeat"
template.bindings['if'].close();