C-like data types in µPy

[AllanGErnst]

Thanks everyone - I really appreciate it

I have already studied byte arrays and they work great, but I do not understand how there can be so much overhead.
The following code returns 56 and 54 bytes and that is for storing 5 bytes

import sys
ar = bytearray([1,2,3,4,5])
ar2 = bytearray(b'\x01\x02\x03\x04\x05')
print(sys.getsizeof(ar))
print(sys.getsizeof(ar2))

Am I doing something wrong here?
Isn't there any way of storing data without that much overhead and does the sys.getsizeof() returns the memory allocated?

Please note that this is in Python and not MicroPython (forgot my board at the university)!!!

[OutoftheBOTS_]

Here's my experimentation in MicroPython

MicroPython ESP32_LoBo_v3.2.4 - 2018-04-06 on Out of the BOTS with ESP32
Type "help()" for more information.
>>> import uctypes
>>> ar = bytearray([1,2,3,4,5])
>>> ar2 = bytearray(b'\x01\x02\x03\x04\x05')
>>> print(uctypes.sizeof(ar))
5
>>> print(uctypes.sizeof(ar2))
5
>>>

[pythoncoder]

The following is also worth noting:

Code: Select all

>>> import gc, micropython
>>> gc.collect()
>>> micropython.mem_info()
stack: 468 out of 15360
GC: total: 102400, used: 8336, free: 94064
 No. of 1-blocks: 12, 2-blocks: 7, max blk sz: 440, max free sz: 5825
>>> a =[0]*5000
>>> gc.collect()
>>> micropython.mem_info()
stack: 468 out of 15360
GC: total: 102400, used: 28432, free: 73968
 No. of 1-blocks: 15, 2-blocks: 8, max blk sz: 1250, max free sz: 4575
>>> 
>>> 94064-73968
20096
>>> 

Given that a small integer is a machine word of 4 bytes, the overhead on a list of 5000 integers is a mere 96 bytes. The reason for using array.array is not to save RAM. It is to produce an object having the buffer protocol (data elements in contiguous memory locations).