Timer.py

from contextlib import contextmanager
from time import time

class Timer:
    def __init__(self, logger=None, format_str='{:.3f}[s]', prefix=None, suffix=None, sep=' '):
        if prefix: format_str = str(prefix) + sep + format_str
        if suffix: format_str = format_str + sep + str(suffix)
        self.format_str = format_str
        self.logger = logger
        self.start = None
        self.end = None

    @property
    def duration(self):
        if self.end is None:
            return 0
        return self.end - self.start

    def __enter__(self):
        self.start = time()

    def __exit__(self, exc_type, exc_val, exc_tb):
        self.end = time()
        out_str = self.format_str.format(self.duration)
        if self.logger:
            self.logger.info(out_str)
        else:
            print(out_str)