[Tutor] Generator next()

[Keith Winston]

Also: it works fine (in it's original form, before I  changed the print
statements) in 2.7, so I'm reinforced in my thinking that it's a 3.3 issue
(well, a changed syntax issue).

Finally: this isn't really a Python issue I don't think, but when I cut &
paste code from the web page above (in Firefox in Linux 16 XFCE) and paste
it into the IDLE New File window, it cleans out all the white space, which
is slightly suboptimal for Python! Any suggestions?


On Fri, Dec 27, 2013 at 1:14 PM, Keith Winston <keithwins at gmail.com> wrote:

> I am beginning to think about decorators, generators, and the like. I'm
> starting from zero. I've read a few PEPs, and looked at some code, and
> maybe things are starting to sink in, though I don't really have enough
> framework to hang it all on. It'll come. Anyway, I was trying to run some
> timing code I swiped off the web, but ran into a problem with the .next()
> function, which I THINK relates to the changes between how generators are
> implemented between pre-3.3 and post, but I can't really tell. Here's the
> code, stolen without apology from here:
> http://enja.org/2011/03/09/a-python-function-timing-decorator/
>
> import time
>
> class Timing(object):
>     def __init__(self):
>         self.timings = {}
>         self.col = self.__collector()
>         self.col.next() #coroutine syntax
>
>     def __collector(self):
>         while True:
>             (name, t) = (yield) #coroutine syntax
>             if name in self.timings:
>                 self.timings[name]["timings"] += [t]
>                 self.timings[name]["count"] += 1
>                 self.timings[name]["total"] += t
>             else:
>                 self.timings[name] = {} #if this entry doesn't exist yet
>                 self.timings[name]["timings"] = [t]
>                 self.timings[name]["count"] = 1
>                 self.timings[name]["total"] = t
>
>     def __call__(self, func):
>         """Turn the object into a decorator"""
>         def wrapper(*arg, **kwargs):
>             t1 = time.time() #start time
>             res = func(*arg, **kwargs) #call the originating function
>             t2 = time.time() #stop time
>             t = (t2-t1)*1000.0 #time in milliseconds
>             data = (func.__name__, t)
>             self.col.send(data) #collect the data
>             return res
>         return wrapper
>
>     def __str__(self):
>         s = "Timings:\n"
>         print(dir(self))
>         for key in self.timings.keys():
>             s += "%s | " % key
>             ts = self.timings[key]["timings"]
>             count = self.timings[key]["count"]
>             total = self.timings[key]["total"]
>             s += "average: %s | total: %s | count: %s\n" % (total / count,
> total, count)
>         return "%s" % s
>
>
> if __name__ == "__main__":
>
>     timings = Timing()
>
>     @timings
>     def add(x,y):
>         for i in range(10000):
>             c = x + y
>         return c
>
>     @timings
>     def multiply(x,y):
>         for i in range(10000):
>             c = x * y
>         return c
>
>     for i in range(100):
>         add(3.,4.)
>         multiply(3., 4.)
>
>     print(timings)
>
>
>
> And here's the error message:
>
> Traceback (most recent call last):
>   File "/home/keithwins/Dropbox/Python/timer1.py", line 50, in <module>
>     timings = Timing()
>   File "/home/keithwins/Dropbox/Python/timer1.py", line 7, in __init__
>     self.col.next() #coroutine syntax
> AttributeError: 'generator' object has no attribute 'next'
> --
> Keith
>



-- 
Keith
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