progress.py

import sys

class ProgressBar(object):
	DEFAULT_BAR_LENGTH = 65
	DEFAULT_CHAR_ON  = '='
	DEFAULT_CHAR_OFF = ' '
	
	def __init__(self, end, start=0):
		self.end    = end
		self.start  = start
		self._barLength = self.__class__.DEFAULT_BAR_LENGTH
		
		self.setLevel(self.start)
		self._plotted = False
		
	def setLevel(self, level):
		self._level = level
		if level < self.start:  self._level = self.start
		if level > self.end:    self._level = self.end
		
		self._ratio = float(self._level - self.start) / float(self.end - self.start)
		self._levelChars = int(self._ratio * self._barLength)
		
	def plotProgress(self):
		sys.stdout.write("\r  %3i%% [%s%s]" %(
			int(self._ratio * 100.0),
			self.__class__.DEFAULT_CHAR_ON  * int(self._levelChars),
			self.__class__.DEFAULT_CHAR_OFF * int(self._barLength - self._levelChars),
		))
		sys.stdout.flush()
		self._plotted = True
		
	def setAndPlot(self, level):
		oldChars = self._levelChars
		self.setLevel(level)
		if (not self._plotted) or (oldChars != self._levelChars):
			self.plotProgress()
			
	def __add__(self, other):
		assert type(other) in [float, int], "can only add a number"
		self.setAndPlot(self._level + other)
		return self
	def __sub__(self, other):
		return self.__add__(-other)
	def __iadd__(self, other):
		return self.__add__(other)
	def __isub__(self, other):
		return self.__add__(-other)
	
	def __del__(self):
		sys.stdout.write("\n")