77 lines
2.2 KiB
Python
77 lines
2.2 KiB
Python
import os
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import sys
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from typing import Any, Dict
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# Avoid "LookupError: unknown encoding: ascii" when open() called in a destructor
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outnull_file = open(os.devnull, "w")
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errnull_file = open(os.devnull, "w")
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STDOUT_FILENO = 1
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STDERR_FILENO = 2
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class suppress_stdout_stderr(object):
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# NOTE: these must be "saved" here to avoid exceptions when using
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# this context manager inside of a __del__ method
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sys = sys
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os = os
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def __init__(self, disable: bool = True):
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self.disable = disable
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# Oddly enough this works better than the contextlib version
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def __enter__(self):
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if self.disable:
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return self
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self.old_stdout_fileno_undup = STDOUT_FILENO
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self.old_stderr_fileno_undup = STDERR_FILENO
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self.old_stdout_fileno = self.os.dup(self.old_stdout_fileno_undup)
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self.old_stderr_fileno = self.os.dup(self.old_stderr_fileno_undup)
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self.old_stdout = self.sys.stdout
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self.old_stderr = self.sys.stderr
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self.os.dup2(outnull_file.fileno(), self.old_stdout_fileno_undup)
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self.os.dup2(errnull_file.fileno(), self.old_stderr_fileno_undup)
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self.sys.stdout = outnull_file
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self.sys.stderr = errnull_file
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return self
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def __exit__(self, *_):
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if self.disable:
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return
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# Check if sys.stdout and sys.stderr have fileno method
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self.sys.stdout = self.old_stdout
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self.sys.stderr = self.old_stderr
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self.os.dup2(self.old_stdout_fileno, self.old_stdout_fileno_undup)
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self.os.dup2(self.old_stderr_fileno, self.old_stderr_fileno_undup)
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self.os.close(self.old_stdout_fileno)
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self.os.close(self.old_stderr_fileno)
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class MetaSingleton(type):
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"""
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Metaclass for implementing the Singleton pattern.
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"""
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_instances: Dict[type, Any] = {}
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def __call__(cls, *args: Any, **kwargs: Any) -> Any:
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if cls not in cls._instances:
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cls._instances[cls] = super(MetaSingleton, cls).__call__(*args, **kwargs)
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return cls._instances[cls]
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class Singleton(object, metaclass=MetaSingleton):
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"""
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Base class for implementing the Singleton pattern.
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"""
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def __init__(self):
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super(Singleton, self).__init__()
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