Beginner: Data type conversion question
Terry Reedy
tjreedy at udel.edu
Fri Jan 16 02:35:54 EST 2009
flagg wrote:
> I am still fairly new to python and programming in general. My
> question is regarding data conversion, I am working on a script that
> will edit dns zone files, one of the functions i wrote handles
> updating the serial number.
> Our zone files use the date as the first part of the serial and a two
> digit integer as the last two.
>
> i.e. 2009011501. The next update would be 2009011502, etc
> Here is the function I wrote, I am using dnspython for reading in zone
> files as Zone "objects". Because dnspython's built-in serial updater
> will not work with how we format our serial's, I have to re-write it.
>
> def checkSerial():
> """
> Checks the current 'date' portion of the serial number and
> checks the current 'counter'(the two digit number at the end of
> the serial number), then returns a complete new serial
> """
> currentDate = time.strftime("%Y""%m""%d", time.localtime())
> for (name, ttl, rdata) in zone.iterate_rdatas(SOA):
> date = str(rdata.serial)[0:8]
> inc = str(rdata.serial)[8:10]
If rdate.serial is already a string, as name would imply, the str() call
is pointless. If not, can you get inc as int more directly?
> if date == currentDate:
> int(inc) + 1
> print inc
> newInc = str(inc).zfill(2)
> serial = date + newInc
> print "date is the same"
> return serial
> elif date < currentDate:
> newInc = "01".zfill(2)
> serial = currentDate + newInc
> print "date is different"
> return serial
>
> Through all of this I am doing a lot of data type conversion. string -
>> integer, integer back to string, etc. Is this an efficient way of
> handling this? I have to perform basic addition on the "inc"
> variable, but also need to expose that value as a string. What I
> have above does work, but I can't help but think there is a more
> efficient way. I guess I am not used to data types being converted so
> easily.
Other than that, you are perhaps worrying too much, even if code could
be squeezed more. The idea that every object knows how to convert
itself to a string representation is basic to Python.
tjr
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