-----Original Message-----
From: Cliff Wells [mailto:[EMAIL PROTECTED]
Sent: Monday, July 31, 2006 4:55 PM
To: Michael Yanowitz
Cc: python-list@python.org
Subject: Re: Static Variables in Python?
On Mon, 2006-07-31 at 15:21 -0400, Michael Yanowitz wrote:
> Is it possible to have a static variable in Python -
> a local variable in a function that retains its value.
>
> For example, suppose I have:
>
> def set_bit (bit_index, bit_value):
> static bits = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
> bits [bit_index] = bit_value
>
> print "\tBit Array:"
> int i
> while (i < len(bits):
> print bits[i],
> print '\n'
>
>
> I realize this can be implemented by making bits global, but can
> this be done by making it private only internal to set_bit()? I don't
> want bits to be reinitialized each time. It must retain the set values
> for the next time it is called.
BTW, I'm assuming this example was contrived. In real life, I wonder
why you'd ever want to use anything besides:
bits = [ 0 ] * 16
bits [ 4 ] = 1
print "Bit Array:"
print ' '.join ( bits )
Having a "set_bit" function seems redundant when the language syntax
directly supports what you are trying to do.
Regards,
Cliff
--
Thanks everyone for your help. Yes I know it is contrived. Well it is
as over-simplified version of what I really want. And yes, I do realize
after sending it about the infinite loop in the printing. I tried too
quickly to come up with a good example without testing it first.
I like the class idea, however I realize that the class object itself
has to be global. I will look into the decorators - something which I have
avoided until now.
I tried creating a class, but got an error:
# ********* class BitsClass *****************************************
class BitsClass (object):
def __init__(self, num_bits):
self.bits=[]
for i in range(num_bits):
self.bits.append(0)
def set(self, bit_index, value):
self.bits[bit_index] = value
return self.bits
def get(self, bit_index):
if ((bit_index >= 0) and (bit_index < len(self.bits))):
return self.bits[bit_index]
else:
return scenario_globals.ERROR_
def display(self):
i = 0
while (i < len(self.bits)):
print self.bits[i],
i += 1
print '\n',
global the_bits
the_bits = BitsClass(16)
# inside another function I have:
global the_bits
the_bits.set(index, value)
but I get back:
Traceback (most recent call last):
...
File "scenario_sync.py", line 245, in get_discrete_data
the_bits.set(index, value)
AttributeError: 'DiscreteBits' object has no attribute 'set'
There is
I was also disappointed, I was hoping I could use BitsClass.print()
instead of BitsClass.display().
Thanks in advance:
Michael Yanowitz
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