Re: Feature Request: type() consult __type for userdata

[David Haley <dchaley@...>]

On this day of 01/18/2008 09:14 PM, Greg Fitzgerald saw fit to scribe:
> Hi Luiz,
> 
>>> Would there be any downside to Lua's 'type()' returning the value of a
>>> '__type' metamethod if its type is 'userdata'?
>>> return t == "userdata" and mt and mt.__type or t
> 
>> Yes, it'd break all programs that rely on type returning "userdata"...
> 
> How so?  It would only break programs with userdata types that have a
> metamethod named "__type".  All others would continue to return
> "userdata".  Do many (any?) Lua programs make use of a __type metamethod?

It's not that it would break programs that already have __type (although
it would do that too); more importantly it would break programs that
depending on seeing 'userdata' and not, say, 'carray' from a call to
'type' on an object, in order to distinguish userdata from other types.

Cheers,
- David

-- 
~David-Haley
http://david.the-haleys.org