On Sun, 17 Apr 2005 15:02:12 -0700, Brian Sabbey
<[EMAIL PROTECTED]> wrote:
Brian Sabbey wrote:
> I'm kicking myself for the first example I gave in my original post in
> this thread because, looking at it again, I see now that it really gives
> the wrong impression about what I want thunks to be in python. The
> 'thunkit' function above shouldn't be in the same namespace as the thunk.
> It is supposed to be a re-usable function, for example, to acquire and
> release a resource. On the other hand, the 'foo' function is supposed to
> be in the namespace of the surrounding code; it's not re-usable. So your
> example above is pretty much the opposite of what I was trying to get
> across.
This would explain why I'm having trouble seeing it then.
> def pickled_file(thunk, name):
> f = open(name, 'r')
> l = pickle.load(f)
> f.close()
> thunk(l)
> f = open(name, 'w')
> pickle.dump(l, f)
> f.close()
>
> Now I can re-use pickled_file whenever I have to modify a pickled file:
>
> do data in pickled_file('pickled.txt'):
> data.append('more data')
> data.append('even more data')
>
> In my opinion, that is easier and faster to write, more readable, and less
> bug-prone than any non-thunk alternative.
>
The above looks like it's missing something to me. How does 'data'
interact with 'thunk(l)'? What parts are in who's local space?
This might be the non-thunk version of the above.
def pickled_file(thunk, name):
f = open(name, 'r')
l = pickle.load(f)
f.close()
thunk(l)
f = open(name, 'w')
pickle.dump(l, f)
f.close()
def data_append(L):
L.append('more data')
L.append('still more data')
pickled_file(data_append, name)
I don't think I would do it this way. I would put the data
list in a class and add a method to it to update the pickle file. Then
call that from any methods that update the data list.
>> def with_file: # no argument list, local group.
>> f = open(filename)
>> t = callback(f)
>> f.close
>>
>> def my_read(f):
>> return f.read()
>>
>> callback = my_read
>> filename = 'filename'
>> do with_file
>
> This wouldn't work since with_file wouldn't be re-usable. It also doesn't
> get rid of the awkwardness of defining a callback.
As long as the name with_file isn't rebound to something else it could
be used as often as needed. I admit there are better ways to do it
though.
Cheers,
Ron
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