genexp init vs listcomp

gen_exps_init.py

#!/usr/bin/env python3

symbols = "$¢£¥€¤"
output = tuple(ord(symbol) for symbol in symbols)
print(output)
# If the generator expression is the single argument in a function call, there is no
# need to duplicate the enclosing parentheses.

import array

output = array.array("I", (ord(symbol) for symbol in symbols))
print(output)
# The array constructor takes two arguments, so the parentheses around the gen‐
# erator expression are mandatory. The first argument of the array constructor
# defines the storage type used for the numbers in the array.

colors = ["black", "white"]
sizes = ["S", "M", "L"]
for tshirt in (f"{c} {s}" for c in colors for s in sizes):
    print(tshirt)
# The generator expression yields items one by one; a list with all six T-shirt varia‐
# tions is never produced.

"""
To initialize tuples, arrays, and other types of sequences, you could start from a
listcomp, but a genexp (generator expression) saves memory because it yields items
one by one using the iterator protocol instead of building a whole list just to feed
another constructor.
"""