Stopwatch - A simple class for taking time hacks.

example.py

from time import sleep
from .stopwatch import Stopwatch

watch = Stopwatch()
watch.start()

sleep(1)
watch.lap('built query')

sleep(1)
watch.lap('ran query')

sleep(1)
watch.stop('formatted results')

watch.report()
"""
1)    1.0s - built query
2)    1.0s - ran query
3)    1.0s - formatted results
-----------------------
      3.0s - Total Time
"""

Stopwatch.py

from datetime import datetime, timedelta
import sys

class Stopwatch:
    def __init__(self):
        self._hacks = []

    @property
    def laps(self):
        return len(self._hacks) - 1

    def start(self, label='start'):
        self._add_hack(label)

    def stop(self, label='stopped'):
        self._add_hack(label)

    def lap(self, label=None):
        assert self._hacks
        self._add_hack(label)

    def _add_hack(self, label):
        self._hacks.append((datetime.now(), label))

    def time(self, lap=None):
        if self.laps == -1:
            return None
        elif self.laps == 0:
            return datetime.now() - self._hacks[0][0]
        elif lap is None:
            return self._hacks[-1][0] - self._hacks[0][0]
        else:
            return self._hacks[lap + 1][0] - self._hacks[lap][0]

    def print_report(self):
        print(self.report())
        sys.stdout.flush()

    def report(self):
        def delta(previous, current):
            ptime = self._hacks[previous][0]
            ctime, label = self._hacks[current]
            return (ctime - ptime, label)

        def format_delta(delta, label):
            return "{:6.1f}s - {}".format(delta.total_seconds(), label)
        
        def generate_report():
            hacks = len(self._hacks)
            padlen = len(str(hacks))
            format_index = lambda idx: str(idx).zfill(padlen) + ') '
            for i, j in zip(xrange(hacks), xrange(1, hacks)):
                yield format_index(j) + format_delta(*delta(i, j))
            summary = ' ' * len(format_index(0)) + format_delta(self.time(), 'Total Time')
            yield '-' * len(summary)
            yield summary

        return "\n".join(generate_report())