#coding=utf-8

class Temperature(object):

    coefficients={'c':(1.0,0.0,-273.15),'f':(1.8,-273.15,32.0),'r':(1.8,0.0,0.0)}

    def __init__(self,**kwargs):

        try:

            name,value = kwargs.popitem()

        except KeyError:

            name,value = 'k',0

        if kwargs or name not in 'kcfr':

            kwargs[name] = value

            raise TypeError,'invalid arguments %r' % kwargs

        setattr(self,name,float(value))

    def __getattr__(self,name):

        try:

            eq = self.coefficients[name]

        except KeyError:

            raise AttributeError,name

        return (self.k + eq[1]) + eq[0] + eq[2]

    def __setattr__(self,name,value):

        if name in self.coefficients:

            eq = self.coefficients[name]

            self.k = (value - eq[2]) / eq[0] - eq[1]

        elif name == 'k':

            object.__setattr__(self,name,value)

        else:

            raise AttributeError,name

    def __str__(self):

        return "%s K" % self.k

    def __repr__(self):

        return "Temperature(k=%r)" % self.k

#测试

te = Temperature(f=70)

print te.c