Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
On Wednesday 11 December 2002 03:43 am, Dmitry Vasiliev wrote: Casey Duncan wrote: On Tuesday 10 December 2002 03:14 pm, Guido van Rossum wrote: Can we get the same patch without the generic except:, please? the last thing I want is a database corruption caused by resizing the Edit box... Why would this particular except clause cause database corruption? I think Leonard is refering to catching ConflictErrors. However I don't think int() touches the database ;^). I saw try: int() except: pattern in many places through all the Zope code. I think catching ValueError only does the job, but then we should replace it in all the places. :-) Nope, as Guido pointed out (and he should know ;^), Int can raise miriad exceptions. not just ValueError. IMO as long as the int is the *only* thing happening in the try block and you comment the bare except, then we are ok. Changing the except clause will only introduce bugs. -Casey ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
I saw try: int() except: pattern in many places through all the Zope code. I think catching ValueError only does the job, but then we should replace it in all the places. :-) Yes, catching ValueError is sufficient for string conversions to int. I thought you could get an OverflowError, but that can only happen when the input is a Python long or float -- int(999) raises ValueError, as does int(xxx). --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
I think this would be a useful note for the Zope3 style guide. What exceptions can int() raise? On converting a preexisting value to an int: ValueError, OverflowError, TypeError, AttributeError (Any others?) On converting an instance that implements __int__: Anything at all. It can even return a non-int value. On evaluating the expression inside the int() brackets: Anything at all. Anything can raise MemoryError. On converting an 8bit string to an int: ValueError *only* On converting a Unicode string to an int: ValueError UnicodeError (or UnicodeEncodeError, which is a subclass of it) --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
Anything can raise MemoryError. Ok. But I don't think regular application code should catch these. Correct. On converting an 8bit string to an int: ValueError *only* Ok. On converting a Unicode string to an int: ValueError UnicodeError (or UnicodeEncodeError, which is a subclass of it) Can you provide an example of raising a unicode error like this: u = makeUnicodeString() # your choice of function int(u) In Python 2.3, I get this: int(u\u1234) Traceback (most recent call last): File stdin, line 1, in ? UnicodeEncodeError: 'decimal' codec can't encode character '\u1234' in position 0: invalid decimal Unicode string In Python 2.2, this raises ValueError. I think I may have to report this as a bug in Python 2.3 though. My point is that once you have a valid unicode object, I don't see how calling int(valid_unicode_object) will raise a UnicodeError. If this is so, then the style should be: value = expression_to_compute_value try: i = int(value) except ValueError: # take corrective action rather than: try: i = int(expression_to_compute_value) except: # Note: calling 'int()' can raise just about anything # take corrective action Even if we decide that we have to use a bare except after all, the expression_to_compute_value should still be moved outside the try/except. --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
Can you provide an example of raising a unicode error like this: u = makeUnicodeString() # your choice of function int(u) In Python 2.3, I get this: int(u\u1234) Traceback (most recent call last): File stdin, line 1, in ? UnicodeEncodeError: 'decimal' codec can't encode character '\u1234' in position 0: invalid decimal Unicode string In Python 2.2, this raises ValueError. I spoke too soon. UnicodeEncodeError is a subclass of ValueError. So catching ValueError from int(str_or_unicode) is the way to go. Who's writing that Zope 3 style guide again? --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
[Zope-dev] BUG: ValueError while changing height of the template edit window
Hi All! Zope 2.6: pressing of Taller or Shorter buttons of the page template edit window raises ValueError. Patch attached. -- Dmitry Vasiliev (dima at hlabs.spb.ru) Index: ZopePageTemplate.py === RCS file: /cvs-repository/Zope/lib/python/Products/PageTemplates/ZopePageTemplate.py,v retrieving revision 1.44 diff -u -r1.44 ZopePageTemplate.py --- ZopePageTemplate.py 18 Sep 2002 15:12:46 - 1.44 +++ ZopePageTemplate.py 10 Dec 2002 14:33:43 - @@ -155,8 +155,11 @@ cols = min(cols, 100) # Max width 100% cols = %d%% % cols # Add percent sign back on else: # Absolute width -try: cols = int(width) -except: cols = max(40, int(dtpref_cols) + szchw.get(width, 0)) +try: +cols = int(width) +except: +cols = max(40, int(dtpref_cols[:-1]) + szchw.get(width, 0)) +cols = %d%% % cols # Add percent sign back on try: rows = int(height) except: rows = max(1, int(dtpref_rows) + szchh.get(height, 0))
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
Please submit a collector issue for this http://collector.zope.org/Zope so the patch doesn't get lost. Thanks. -Casey On Tuesday 10 December 2002 10:07 am, Dmitry Vasiliev wrote: Hi All! Zope 2.6: pressing of Taller or Shorter buttons of the page template edit window raises ValueError. Patch attached. -- Dmitry Vasiliev (dima at hlabs.spb.ru) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
Can we get the same patch without the generic except:, please? the last thing I want is a database corruption caused by resizing the Edit box... Why would this particular except clause cause database corruption? int() happens to raise a bunch of different exceptions, and I think an unqualified except: clause is okay here (though it needs a comment). Also note that the unpatched code has an unqualified except: already, so you can't really blame Dmitry. --Guido van Rossum (home page: http://www.python.org/~guido/) ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] BUG: ValueError while changing height of the template edit window
On Tuesday 10 December 2002 03:14 pm, Guido van Rossum wrote: Can we get the same patch without the generic except:, please? the last thing I want is a database corruption caused by resizing the Edit box... Why would this particular except clause cause database corruption? I think Leonard is refering to catching ConflictErrors. However I don't think int() touches the database ;^). int() happens to raise a bunch of different exceptions, and I think an unqualified except: clause is okay here (though it needs a comment). Yup and please reformat the other try: except: if you reformat the first one. Also note that the unpatched code has an unqualified except: already, so you can't really blame Dmitry. I say blame Canada! -Casey ___ Zope-Dev maillist - [EMAIL PROTECTED] http://lists.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - http://lists.zope.org/mailman/listinfo/zope-announce http://lists.zope.org/mailman/listinfo/zope )
