[Tutor] Zipfile and File manipulation questions.

[Jonathon Sisson]

Chris Hengge wrote:
> I chose the way I used the names because to me...
> 
> outFile = open(aFile.lower(), 'w') # Open output buffer for writing.
> = open a file with lowercase name for writing.
> it is implied that aFile is from the zip, since it is created in the 
> loop to read the zip..
> 
> outFile.write(zFile.read(insideZip)) # Write the file.
> = write what is read from inside the zip file.
> 
> I guess for declaration it isn't very clear, but thats what comments are 
> for?
> My naming was purely for my ease of mind.. I personally care less about 
> what I call it when I declare, as to how it logically flows when I go to 
> use it. I'm sure this is considered poor method, but once I declare a 
> method I tend to never need to change the declaration, just how I use 
> the info... I hope that makes sense.
> 

Even if you're the only person that EVER lays eyes on that code (and you 
inherited Perl code, so I assume someone will eventually take this code 
over) it's vital to use names that are clear and concise.  If you 
disagree, put your code away in a locked box, then re-read it after six 
months and see if it makes perfect sense.

As Kent said, this is quite a minor issue that shouldn't be paraded, but 
I have been on the receiving end of code such as:


int a;

if (a == 0)
{
	/* do something interesting */
}
else
{
	/* do something less interesting */
}

(Sorry for the Java-ish flair...Java happens to be on my mind at the 
moment...)

Even if I was there when the code was written, how could I know what "a" 
means a month later without digging back through to see how it's used? 
(and worse, "a" was used for conditional testing  in this specific 
example (i.e. on/off conditions), so a boolean would have done MUCH 
better).  Commenting can only help so much...the code must speak for 
itself at some point.  (Yes, I know this is an extreme example, but it 
happens all the time).

Something like this is much more readable:


boolean fileExists;

if (fileExists)
{
	/* do something interesting */
}
else
{
	/* do something less interesting */
}


I'm not complaining, because afterall it's up to you to write the code 
you're comfortable with (because you're not working on a team, that is), 
but a friendly suggestion on naming conventions (especially when you can 
refactor in most IDE's today) could go a long ways to helping you build 
readable code that is easier to maintain.

Jonathon


> On 10/16/06, *Kent Johnson* <kent37 at tds.net <mailto:kent37 at tds.net>> wrote:
> 
>     Chris Hengge wrote:
>      > Here is my solution, completed with (I think) all your suggestions...
>      >
>      >
>     #########################################################################
>      > def extractZip(filePathName):
>      >     """
>      >     This method recieves the zip file name for decompression,
>     placing the
>      >     contents of the zip file appropriately.
>      >     """
>      >     if filePathName == "":
>      >         print "No file provided...\n"
>      >     else:
>      >         try: # Attempt to unzip file.
>      >             zFile = zipfile.ZipFile(filePathName.strip('"'), "r")
>      >             for aFile in zFile.namelist(): # For every file in
>     the zip.
>      >                 # If the file ends with a needed extension,
>     extract it.
>      >                 for ext in ['.cap', '.hex', '.fru', '.cfg', '.sdr']:
>      >                     if aFile.lower().endswith(ext):
>      >                         insideZip = aFile # Copy of Filename.
>      >                         if "/" in aFile: # Split the filename if '/'.
>      >                           aFile = aFile.rsplit('/', 1)[-1]
>      >                         elif  "\\" in aFile: # Split the filename
>     if '\'.
>      >                           aFile = aFile.rsplit('\\',
>      > 1)[-1]
>      >                         outfile = open( aFile.lower(), 'w') # Open
>      > output buffer for writing.
>      >                         outfile.write(zFile.read(insideZip)) #
>     Write the
>      > file.
>      >                         outfile.close() # Close the output file
>     buffer.
>      >             print "Resource extraction completed successfully!\n"
>      >         except IOerror, message: # If file creation fails, let
>     the user
>      > know.
>      >             print "File could not be written: \n"
>      >             print message
>      >
>      >
>     #########################################################################
>      > Definatly an improvement! Thanks Kent.
> 
>     Yes, that is what I meant. One minor quibble, I think I would keep
>     aFile
>       as the name in the zip, since that is what it starts as, and use a new
>     name for the external file name. Maybe you could use better names, for
>     example zipPath and fileName. I think that would make the code a little
>     clearer but it is a very minor point.
> 
>     Kent
> 
> 
> 
> 
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