Allow from_tuples to accept and iterator
Since many methods of constructing a list of tuples in Python3 return iterators, this flattens them. Although using from_arrays often works better.

tests and a usecase example pls.
 That proposal also copies an existing list, which would have some performance impact where `tuples` were already a list.

You could have a function that checks if something in an iterator (or isn't a `Sized`), and coerces it to a list if an iterator. 
You could also try and delay checking the `len` until later, after the iterator would have been iterated, and see if users would get reasonable error messages where there is a break.
 pls reopen if you wish to update according to comments
 Thanks Jeff,

Will do if I have some time to complete.

Spencer

On 1/27/2016 11:00 AM, Jeff Reback wrote:

> pls reopen if you wish to update according to comments
> 
> —
> Reply to this email directly or view it on GitHub 
> https://github.com/pydata/pandas/pull/12119#issuecomment-175707418.
