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@simple_debug
Jesse 发表于 2008-07-12 20:19:29
Update(08-07-22):
I continued with <Learning Python>, which enlightened me with this @.
@ brings what is called 'function decorator', and it's VERY simple, much simpler than what I wrote below ;-)
1 @foo # foo be a callable object
2 def bar():
3 ...
The above code works as: bar = foo(bar). No more, no less.
It again reflects the simple YET powerful nature of Python. Enjoy !-)
####original stuff########
In the source of gnome-sudoku, they use '@simple_debug' to debug and step through the program. However, I can't find a lesson on Python's '@' on the web. How to let google search such non-alphanumberic characters for me?
But I tried out this @, as following.
Try this,
###########
def bar (par1):
print 'in bar with', par1
def debug (f):
print 'in debug'
return bar
@debug
def foo (a):
print 'FOO!', a
foo('hello')
###########
output:
in debug
in bar with hello
###########
How does it work?
1. First use '@' before a function define(foo here).
2. When you call foo(), Python will not run foo(), instead, the function after '@', debug() here, is executed.
3. Python hands foo to debug() as a argument and debug() is supposed to return one function, bar() here.
4. Moreover, the returned function bar() should receive the same parameters as the defined foo
5. Then besides foo is itself passed to debug(), foo's arguments are passed to bar.
6. bar() with arguments from foo is executed.
foo() is NOT executed.
In order to run foo(), we have to do so manually in debug() and bar(). This is how gnome-sudoku does:
###########
1if options.debug:
2 def simple_debug (f):
3 def _ (self, *args,**kwargs):
4 print self.__class__,f.__name__,args,kwargs
5 return f(self,*args,**kwargs)
6 return _
###########
The original function f runs at line 5 and its return value is returned as well.
To debug all kinds of function, it use *args and **kwargs.
###########
Then following definition let simple_debug do nothing.
else:
def simple_debug (f): return f
###########
Jesse
I continued with <Learning Python>, which enlightened me with this @.
@ brings what is called 'function decorator', and it's VERY simple, much simpler than what I wrote below ;-)
1 @foo # foo be a callable object
2 def bar():
3 ...
The above code works as: bar = foo(bar). No more, no less.
It again reflects the simple YET powerful nature of Python. Enjoy !-)
####original stuff########
In the source of gnome-sudoku, they use '@simple_debug' to debug and step through the program. However, I can't find a lesson on Python's '@' on the web. How to let google search such non-alphanumberic characters for me?
But I tried out this @, as following.
Try this,
###########
def bar (par1):
print 'in bar with', par1
def debug (f):
print 'in debug'
return bar
@debug
def foo (a):
print 'FOO!', a
foo('hello')
###########
output:
in debug
in bar with hello
###########
How does it work?
1. First use '@' before a function define(foo here).
2. When you call foo(), Python will not run foo(), instead, the function after '@', debug() here, is executed.
3. Python hands foo to debug() as a argument and debug() is supposed to return one function, bar() here.
4. Moreover, the returned function bar() should receive the same parameters as the defined foo
5. Then besides foo is itself passed to debug(), foo's arguments are passed to bar.
6. bar() with arguments from foo is executed.
foo() is NOT executed.
In order to run foo(), we have to do so manually in debug() and bar(). This is how gnome-sudoku does:
###########
1if options.debug:
2 def simple_debug (f):
3 def _ (self, *args,**kwargs):
4 print self.__class__,f.__name__,args,kwargs
5 return f(self,*args,**kwargs)
6 return _
###########
The original function f runs at line 5 and its return value is returned as well.
To debug all kinds of function, it use *args and **kwargs.
###########
Then following definition let simple_debug do nothing.
else:
def simple_debug (f): return f
###########
Jesse
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