问题：route中的装饰器为什么感觉和平时使用的不太一样，装饰器带参数和不太参数有什么区别？被修饰的函数带参数和不带参数有什么区别？
测试1：装饰器不带参数，被修饰的函数也不带参数。
def log(func):
print"execute log"
print func
def use_log():
print "execute use log"
def wrapper():
print "start"
func()
print "end"
return
return wrapper
return use_log
@log
def cal():
print "1+2"
此时输出为：
execute log <function cal at 0x7fa64535f668> #这里的function为cal的函数地址
如果执行cal()那么将会使用use_log函数，返回的是wrapper()
execute log <function cal at 0x7f42ee7a4668> execute use log
如果执行cal()的返回值，那么将执行cal()函数体的内容
result = cal() result()
结果为：
execute log <function cal at 0x7f38dc4d1668> execute use log start 1+2 end
测试2：如果装饰器带参数，被修饰的函数不带参数
def log(func): #这里的func为装饰器函数参数
print"execute log"
print func #这里的func为装饰器函数参数
def use_log(func): #这里的func为函数cal()的地址
print "execute use log"
print func #这里的func为函数cal()的地址
def wrapper():
print "start"
func()
print "end"
return
return wrapper
return use_log
@log('log')
def cal():
print "1+2"
#这个时候数输出结果为：
execute log
log
execute use log
<function cal at 0x7f0c666b46e0>
这个时候调用cal()那么将会执行wrapper()的函数体+cal()的函数体。
测试3：如果装饰器不带参数，被修饰的函数带参数
def log(func): #func 为cal()函数的地址
print"execute log"
def use_log(param): #param为cal的参数param
print "execute use log"
print param
def wrapper():
print "start"
func(param) #func 为cal()函数的地址，param为cal的参数param
print "end"
return
return wrapper
return use_log
@log
def cal(param):
print "1+2"
result = cal('cal')
result()
#执行的结果为：
execute log
execute use log
cal
start
1+2
end
#如果注掉最后两行代码，那么只有输出
execute log
测试4：如果装饰器带参数，被修饰的函数也带参数。最复杂的情况。
def log(func): #func为装饰器的参数
print"execute log"
def use_log(func): #func为cal的函数地址
print "execute use log"
print func #func为cal的函数地址
def wrapper(param): #param为cal的参数
print "start"
func(param)
print "end"
return
return wrapper
return use_log
@log('test')
def cal(param):
print "1+2"
result = cal('cal')
#执行的结果为：
execute log
execute use log
<function cal at 0x7f23bbc6d6e0>
start
1+2
end
经过上面的分析之后，再看flask中使用的是哪种情况：
样例代码：
from flask import Flask
app = Flask(__name__)
@app.route('/')
def hello():
print 'execute hello function'
return 'Hello, World!'
@app.route('/')的代码如下：
def route(self, rule, **options):
"""A decorator that is used to register a view function for a
given URL rule. This does the same thing as :meth:`add_url_rule`
but is intended for decorator usage::
@app.route('/')
def index():
return 'Hello World'
For more information refer to :ref:`url-route-registrations`.
:param rule: the URL rule as string
:param endpoint: the endpoint for the registered URL rule. Flask
itself assumes the name of the view function as
endpoint
:param options: the options to be forwarded to the underlying
:class:`~werkzeug.routing.Rule` object. A change
to Werkzeug is handling of method options. methods
is a list of methods this rule should be limited
to (``GET``, ``POST`` etc.). By default a rule
just listens for ``GET`` (and implicitly ``HEAD``).
Starting with Flask 0.6, ``OPTIONS`` is implicitly
added and handled by the standard request handling.
"""
def decorator(f):
endpoint = options.pop('endpoint', None)
self.add_url_rule(rule, endpoint, f, **options)
print "this param has been accessed"
return f
return decorator
可以看到装饰器的参数为‘/’，被修饰的函数为：hello()，所以这里属于第二种情况，即使不调用hello()函数，decorator的函数体也是被执行的，也就是说，只要使用装饰器添加了路由规则，那么就会被加入到map中形成映射关系。