#!/bin/env python

from sys import stderr

class Logger:

	'''

	An extended file type thing initially equivalent to sys.stderr

	You can add/remove file type things; it has a write method

	'''

	def __init__(self):

		self._fps = [stderr]

		self._fns = {}

	def add(self,fp):

		'''add the file/string fp to the destinations'''

		if type(fp) is StringType:

			if fp in self._fns: return

			fp = open(fn,'wb')

			self._fns[fn] = fp

		self._fps.append(fp)

	def remove(self,fp):

		'''remove the file/string fp from the destinations'''

		if type(fp) is StringType:

			if fp not in self._fns: return

			fn = fp

			fp = self._fns[fn]

			del self.fns[fn]

		if fp in self._fps:

			del self._fps[self._fps.index(fp)]

	def write(self,text):

		'''write text to all the destinations'''

		if text[-1]!='\n': text=text+'\n'

		map(lambda fp,t=text: fp.write(t),self._fps)

	def __call__(self,text):

		self.write(text)

logger=Logger()

class WarnOnce:

	def __init__(self,kind='Warn'):

		self.uttered = {}

		self.pfx = '%s: '%kind

	def once(self,warning):

		if not self.uttered.has_key(warning):

			logger.write(self.pfx + warning)

			self.uttered[warning] = 1

	def __call__(self,warning):

		self.once(warning)

warnOnce=WarnOnce()

infoOnce=WarnOnce('Info')