lists, strings, and byte strings

[Skaperen]

if i want to convert a string to a list then back, again, it's rather easy. if i want to do the same with a byte string it's not. anyone know a way that can be done to both using the same code for either?

[DeaD_EyE]

Hm, let's try:

1	str.join('', list('Hello World'))

Output:
'Hello World'

Success :-)

Now the first try with bytes:

1	bytes.join(b'', list(b'Hello Bytes'))

Error:
TypeError: sequence item 0: expected a bytes-like object, str found

This is the problem with the representation. Iterating over bytes returns integers.

Third try:

1	bytearray(list(b'Hello Bytes'))

Output:
bytearray(b'Hello Bytes')

This looks better.

Finally you can use this:

1	bytes(bytearray(list(b'Hello Bytes')))

Output:
b'Hello Bytes'

But you're right. It's not so easy.

---

Bonus:
Instead of using the list function to construct a list,
use a bytearray. A bytearray is mutable and acts like a list.

1	bytes(bytearray(b'Hello Bytes'))

Output:
b'Hello Bytes'

It's mutable. You can mutate it.

1 2	ba = bytearray(b'Hello Bytes') ba[0] = b'W'

Error:
TypeError: an integer is required

A not so nice solution for it:

1 2	ba[0] = ord(b'W') ba

Output:
bytearray(b'Wello Bytes')

Extending:

1 2	ba.extend(b' This is the next Chunk') ba

Output:
bytearray(b'Wello Bytes This is the next Chunk')

But i know what you mean. Handling with bytes a bit pain in the ass.
There must be a better way.

[Skaperen]

right, iterating over bytes or a bytearray gets a list of ints. and doing so over a string gets a list of strings that are each len() == 1. either of these is easy enough to do and it is easy enough for the same code to do it. but reversing it back is harder, and doing it with the same code is even harder, still. it's the reversing step i want to do. one ambiguity is bytes vs bytearray in python3. given a list of ints, you don't know which to go back to. i'll accept bytearray because it is available in both python2 and python3. btw, the code i seek that can reverse a list back to a string or bytearray, i want it to be the same code working in both python2 and python3 ... python version agnostic code.