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Date: Fri, 17 Jan 2014 09:01:52 +0000
From: Tim Golden <mail@timgolden.me.uk>
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To: python-list@python.org
Subject: Re: Converting folders of jpegs to single pdf per folder
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On 17/01/2014 05:42, vasishtha.spier@gmail.com wrote:
> try:
>      n = 0
>      for dirpath, dirnames, filenames in os.walk(root):
>           PdfOutputFileName = os.path.basename(dirpath) + ".pdf" 
>           c = canvas.Canvas(PdfOutputFileName)
>           if n > 0 :
>                for filename in filenames:
>                     LowerCaseFileName = filename.lower()
>                     if LowerCaseFileName.endswith(".jpg"):
>                          print(filename)
>                          filepath    = os.path.join(dirpath, filename)
>                          print(filepath)
>                          im          = ImageReader(filepath)
>                          imagesize   = im.getSize()
>                          c.setPageSize(imagesize)
>                          c.drawImage(filepath,0,0)
>                          c.showPage()
>                          c.save()
>           n = n + 1
>           print "PDF of Image directory created" + PdfOutputFileName
>            
> except:
>      print "Failed creating PDF"
> -------------------------

One thing I would point out (assuming that this is your final code):
your try-except is too broad, both in terms of the code it encloses and
in terms of the exceptions it traps.

As it stands, your code will drop straight out as soon as it hits an
error, with the message "Failed creating PDF" -- which is what it would
have done anyway, only you've removed the informative traceback which
would have told you what went wrong!

In the circumstances, you presumably want to attempt to recover from
some failure (perhaps caused by a corrupt JPEG or a permissions issue)
and continue to generate the remaning PDFs. In that case, you'd do
better a structure of this sort:

<semi-pseudocode>
import logging
logging.basicConfig()

for d, ds, fs in os.walk("..."):

   # init pdf
   try:
      # create PDF
   except:
     logging.exception("Couldn't create PDF for %s", d)
     continue
   else:
     logging.info("Created PDF for %s", d)
     # write PDF

</semi-pseudocode>

If you could narrow down the range of exceptions you want to recover
from, that would go in the "except:" clause, but in this situation you
might not be in a position to do that.

TJG