Using a Generator with a While loop in Python

Question

I want to be able to do something like this:

while next(gen):
    print(value_from_gen)

I start with this list x=[1,2,3,4,5]

Then I make a generateor to return the values
g = ({i:i*2} for i in x)

When I try:

while val = next(g):
    print(val)

I get:

File "main.py", line 6
    while val = next(g):
              ^
SyntaxError: invalid syntax

When I try:

while next(g):
    print(next())   

It skips some values and I get the error:

{2: 4}
{4: 8}
Traceback (most recent call last):
  File "main.py", line 7, in <module>
    print(next(g))
StopIteration

when I try:

v= -1
while v is not None:
    v=next(g)
    print(v)

I get all the values but still get the error:

{1: 2}
{2: 4}
{3: 6}
{4: 8}
{5: 10}
Traceback (most recent call last):
  File "main.py", line 8, in <module>
     v=next(g)
StopIteration

When I try:

for v in g:
    print(v)

I get the correct result:

{1: 2}
{2: 4}
{3: 6}
{4: 8}
{5: 10} 

However, I am wondering if this is equivalent to calling next(g) and does it keep the laziness benefit of the generator?

Also I am wondering if it is impossible to do this with an actual while loop?

Answer 1

Based on @Brad Martsberger's answer, you may pass False to default parameter of next function too:

while element:= next(g, False):
    print(element)