File size: 2,260 Bytes
5d62acd | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 | import os
import sys
from typing import Any, Dict
# Avoid "LookupError: unknown encoding: ascii" when open() called in a destructor
outnull_file = open(os.devnull, "w")
errnull_file = open(os.devnull, "w")
STDOUT_FILENO = 1
STDERR_FILENO = 2
class suppress_stdout_stderr(object):
# NOTE: these must be "saved" here to avoid exceptions when using
# this context manager inside of a __del__ method
sys = sys
os = os
def __init__(self, disable: bool = True):
self.disable = disable
# Oddly enough this works better than the contextlib version
def __enter__(self):
if self.disable:
return self
self.old_stdout_fileno_undup = STDOUT_FILENO
self.old_stderr_fileno_undup = STDERR_FILENO
self.old_stdout_fileno = self.os.dup(self.old_stdout_fileno_undup)
self.old_stderr_fileno = self.os.dup(self.old_stderr_fileno_undup)
self.old_stdout = self.sys.stdout
self.old_stderr = self.sys.stderr
self.os.dup2(outnull_file.fileno(), self.old_stdout_fileno_undup)
self.os.dup2(errnull_file.fileno(), self.old_stderr_fileno_undup)
self.sys.stdout = outnull_file
self.sys.stderr = errnull_file
return self
def __exit__(self, *_):
if self.disable:
return
# Check if sys.stdout and sys.stderr have fileno method
self.sys.stdout = self.old_stdout
self.sys.stderr = self.old_stderr
self.os.dup2(self.old_stdout_fileno, self.old_stdout_fileno_undup)
self.os.dup2(self.old_stderr_fileno, self.old_stderr_fileno_undup)
self.os.close(self.old_stdout_fileno)
self.os.close(self.old_stderr_fileno)
class MetaSingleton(type):
"""
Metaclass for implementing the Singleton pattern.
"""
_instances: Dict[type, Any] = {}
def __call__(cls, *args: Any, **kwargs: Any) -> Any:
if cls not in cls._instances:
cls._instances[cls] = super(MetaSingleton, cls).__call__(*args, **kwargs)
return cls._instances[cls]
class Singleton(object, metaclass=MetaSingleton):
"""
Base class for implementing the Singleton pattern.
"""
def __init__(self):
super(Singleton, self).__init__()
|