Tuple generator, and function/class syntax

[buran]

There is no such thing as "tuple comprehension". This (x for x in range(100000000)) is generator expression.

Read Generator expressions and list comprehensions and also PEP-0289 for more details.

That said, you need to know that in python 3 range() is lazy and will return range object, i.e. range(100000000) will produce range object and it will be consumed when needed, not generate all numbers in memory (like in python2, where we have lazy xrange()). So basically you create [lazy] generator from lazy range object

you can do list(range(100000000)), set(range(100000000)) and tuple(range(100000000)) to produce list, set or tuple respectively.

Why not instantiate it during creation? For example, why not treat (x for x in range(10)) as (10, 10, 10, 10, 10, 10, 10, 10, 10, 10)

in any case this will never be (10, 10, 10, 10, 10, 10, 10, 10, 10, 10). it will be (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) if it was a tuple and not generator expression...