学习Python中遇到的问题

xglys

最近学习Python中。
先上代码：

# -*- coding: UTF-8 -*-
class Person:
'''Represents a person'''
population=0
def _init_(self,name):
self.name=name
print '初始化参数 %s'%self.name
Person.population+=1
def _del_(self):
'''I am dying'''
print '%s says Bye'%self.name
Person.population-=1
if Person.population==0:
print ' I am the last one'
else:
print 'There are still %d people leftl'%Person.population
def sayHi(self):
'''Greeting by the people.
Really,that's all it does.'''
print 'Hi,My name is %s'%self.name
def howMany(self):
'''print the current population'''
if Person.population==1:
print 'I am the only one person here'
else:
print 'We have %d persons here'%Person.population
print '测试开始！'
toby=Person('toby Huang')
toby.sayHi()
toby.howMany()
jimmy=Person('jimmy Huang')
jimmy.sayHi()
jimmy.howMany()
toby.sayHi()
toby.howMany()

这是我写的一段测试学习代码。报错如下：

Traceback (most recent call last):
File "<pyshell#7>", line 1, in <module>
import ObjVarTest.py
File "ObjVarTest.py", line 29, in <module>
toby=Person('toby Huang')
TypeError: this constructor takes no arguments

下面是正确的代码：

# -*- coding: UTF-8 -*-
class Person:
'''Represents a person'''
population=0
def __init__(self,name):
self.name=name
print '初始化参数 %s'%self.name
Person.population+=1
def __del__(self):
'''I am dying'''
print '%s says Bye'%self.name
Person.population-=1
if Person.population==0:
print ' I am the last one'
else:
print 'There are still %d people leftl'%Person.population
def sayHi(self):
'''Greeting by the people.
Really,that's all it does.'''
print 'Hi,My name is %s'%self.name
def howMany(self):
'''print the current population'''
if Person.population==1:
print 'I am the only one person here'
else:
print 'We have %d persons here'%Person.population
print '测试开始！'
toby=Person('toby Huang')
toby.sayHi()
toby.howMany()
jimmy=Person('jimmy Huang')
jimmy.sayHi()
jimmy.howMany()
toby.sayHi()
toby.howMany()

是不是一眼没看出有什么不一样？
开始的时候我也是快读浏览了下，然后就直接开始写了。知道运行时报错，都一直找不到错在哪？直到写这篇博客前，才发现错误！
其实这真是一个低级错误，原来不是_inti_方法，应该是__init__方法！我少打了一个_。
这都是快速浏览带来的恶果啊，就因为这简单错误害我两天都不爽。
还是那句话：Devil in the details