TypeError: can't convert 'int' object to str implicitly

[BillKujawa]

micropython yields: "TypeError: can't convert 'int' object to str implicitly" where as python does not.

'''
Convert file_read_backwards.py to run on Micropython
https://github.com/RobinNil/file_read_backwards
'''
from file_read_backwards import FileReadBackwards
import gc
import sys

db_file_name_old = "db_cistern.json"
db_file_name = "db_cistern.txt"

if __name__ == "__main__":
    from file_read_backwards import FileReadBackwards
    try:
        with FileReadBackwards(db_file_name, encoding="utf-8", chunk_size=4096) as frb:  # *** line 15 ***
            print(f"{frb.chunk_size=}")

            while True:
                l = frb.readline()
                if not l:
                    break
                print(l, end="")
    except Exception as e:
        print(" error")
        sys.print_exception(e) 

        
# expanded code from buffer_work_space.py to isolate error:

def _get_file_size(fp):
    #return os.fstat(fp.fileno()).st_size  # <<< original error line
    xx = fp.fileno()
    print(f"{fp=}")
    print(f"{xx=}")
    print(f"{type(xx)=}")
    #print(f"{type(os.stat(xx))=}")
    ii = os.stat(xx)  # **************** line 98 **********
    print(f"{ii=}")
    substring = "st_size="
    ii = str(ii)
    index = ii.find(substring)
    print(f"{index=}")
    part_string = ii[index:]
    print(f"{part_string=}")
    split_string = part_string.split(',')
    st_size_string = split_string[0]
    print(f"{st_size_string=}")
    size = int(st_size_string[9:])
    print(f"{size=}")

>>> output running python 3.10.12 in Thonny on Ubuntu 22.04.4 LTS, as expected.

>>> Same output produced by running python3 from terminal.

fp=<_io.BufferedReader name='db_cistern.txt'>
fp=<_io.BufferedReader name='db_cistern.txt'>
xx=5
type(xx)=<class 'int'>
ii=os.stat_result(st_mode=33204, st_ino=5802792, st_dev=66311, st_nlink=1, st_uid=1000, st_gid=1000, st_size=2831, st_atime=1709767783, st_mtime=1709436172, st_ctime=1709436172)
index=98
part_string='st_size=2831, st_atime=1709767783, st_mtime=1709436172, st_ctime=1709436172)'
st_size_string='st_size=2831'
size=831
self.iterator=<file_read_backwards.FileReadBackwardsIterator object at 0x7fb0b5a415d0>
frb.chunk_size=4096
seek_position=0  read_size=831
{"
{"M": 3, "T": 67.1, "D": 1, "L": 1346, "Y": 2024, "H": 22, "Min": 44}
{"M": 3, "T": 67.1, "D": 1, "L": 450, "Y": 2024, "H": 22, "Min": 47}
{"M": 3, "T": 67.1, "D": 1, "L": 216, "Y": 2024, "H": 22, "Min": 41}
{"M": 3, "T": 70.7, "D": 1, "L": 949, "Y": 2024, "H": 18, "Min": 8}

>>> output running micropython pulled from github on 2/25/2024 and compiled locally:

fp=<io.FileIO 3>
fp=<io.FileIO 3>
xx=3
type(xx)=<class 'int'>
 error
Traceback (most recent call last):
  File "cistern_db_convert.py", line 15, in <module>
  File "/home/bill/snap/thonny/214/file_read_backwards.py", line 42, in __init__
  File "/home/bill/snap/thonny/214/file_read_backwards.py", line 90, in __init__
  File "/home/bill/snap/thonny/214/buffer_work_space.py", line 25, in __init__
  File "/home/bill/snap/thonny/214/buffer_work_space.py", line 98, in _get_file_size
TypeError: can't convert 'int' object to str implicitly

>>> expected result from running on python:
ii=os.stat_result(st_mode=33204, st_ino=5802792, st_dev=66311, st_nlink=1, st_uid=1000, st_gid=1000, st_size=2831, st_atime=1709767783, st_mtime=1709436172, st_ctime=1709436172)

[jimmo]

@BillKujawa Please see Welcome (Please read before posting) for how to format code in Discussions posts. (I will edit your post)

[jimmo]

@BillKujawa I assume you're using the unix port of MicroPython, which is the only place where f.fileno() is implemented.

On the embedded ports, there is no concept of file descriptors, so in general MicroPython has fairly limited support for them. e.g. os.stat() only support a string path, not a file descriptor. The TypeError is because it's trying to interpret the argument as a path (i.e. a string).

[BillKujawa]

Thank you. Project was wishful thinking on my part.