Nested TwiML can be retroactively modified.

[jmatth]

The few TwiML verbs that take nested interfaces currently take struct pointers, which makes it possible to do something like this:

inner := new(twiml.DialTwiml)
inner.Number(NumberOpts{} "123")
response.Dial(DialOpts{}, inner)
inner.Sip(SipOpts{}, "sip:something")

The rendered TwiML would then have the sip directive in there. This is probably not expected behavior, and also makes implementing caching on the Render method rather difficult.

[natebrennand]

the cache flag could be in all the inner structs and then we set it accordingly?

alternatively make a very explicit warning and provide both a Render() and ForceRender() methods, the latter for ignoring the cache