Python style guidelines

[beliavsky]

Is there a more recent set of Python style guidelines than PEP 8,
"Style Guide for Python Code", by van Rossum and Warsaw, at
http://www.python.org/peps/pep-0008.html , which is dated July 5,
2001?

[Skip Montanaro]

beliavsky> Is there a more recent set of Python style guidelines than
beliavsky> PEP 8, "Style Guide for Python Code", by van Rossum and
beliavsky> Warsaw, at http://www.python.org/peps/pep-0008.html , which
beliavsky> is dated July 5, 2001?

Is there something missing you think should be there? There's no particular
reason a PEP needs to be continually updated. In particular, notions of
good Python style haven't changed a lot over the past ten years.

Skip

[Josef Meile]

> Is there something missing you think should be there? There's no particular

reason a PEP needs to be continually updated. In particular, notions of
good Python style haven't changed a lot over the past ten years.

Skip

I agree, those are good guidelines, but I don't agree with:

- Don't compare boolean values to True or False using == (bool
types are new in Python 2.3):

No: if greeting == True:
Yes: if greeting:

What would happened if you do:

a='test'
if a.find('foo'): .... print "foo was found"
....
foo was found

I think you should never do a direct boolean comparison. Instead
one should use a more elaborate boolean expresion like:
a='test'
if a.find('foo') >= 0:

.... print "foo was found"
....
You will have problems specially if you come from languages where
values minor than zero are considered to be false. I think the
previous sintax is ambiguous.

Regards,
Josef

[Peter Otten]

Josef Meile wrote:

Is there something missing you think should be there? There's no
particular
reason a PEP needs to be continually updated. In particular, notions of
good Python style haven't changed a lot over the past ten years.

Skip

I agree, those are good guidelines, but I don't agree with:

- Don't compare boolean values to True or False using == (bool
types are new in Python 2.3):

No: if greeting == True:
Yes: if greeting:

What would happened if you do:

>>> a='test'
>>> if a.find('foo'): ... print "foo was found"
...
foo was found

I think you should never do a direct boolean comparison. Instead
one should use a more elaborate boolean expresion like:
>>> a='test'
>>> if a.find('foo') >= 0:

... print "foo was found"
...
You will have problems specially if you come from languages where
values minor than zero are considered to be false. I think the
previous sintax is ambiguous.

I think your find() example has nothing to do with

if boolVal == True:

versus

if boolVal:

though it might be a pitfall for people coming from languages with 1-based
indices. If you discard the index it returns anyway, you could use the
clearer

if "foo" in a:

instead.

As to the original issue, I disagree with you and prefer the recommended
style. I find it natural even for non-booleans:

greeting = "Hi"
if greeting:
print greeting

If you expect a boolean value and fear that you may erroneously encounter
something else, the value == True test will not be sufficient anyway,
because treating, say, "Hi" as False may be an error, too. It's

if greeting == True:
...
elif greeting == False:
pass
else:
raise AssertionError, "greeting must be True or False"

versus

assert greeting in (True, False), "greeting must be True or False"
if greeting:
...

then, and again the last wins at in my eyes.

Peter

[Heather Coppersmith]

On Thu, 11 Mar 2004 10:48:35 +0100,
Josef Meile <jm****@hotmail .com> wrote:

Is there something missing you think should be there? There's no particular
reason a PEP needs to be continually updated. In particular, notions of
good Python style haven't changed a lot over the past ten years.
Skip I agree, those are good guidelines, but I don't agree with:

- Don't compare boolean values to True or False using == (bool
types are new in Python 2.3): No: if greeting == True:
Yes: if greeting: What would happened if you do:

a='test'
if a.find('foo'): ... print "foo was found"
...
foo was found

a.find does not return a boolean, so that particular style guideline
does not apply.

if a.find( 'foo' ) == True:

.... print 'foo was found'

probably isn't what you want either. ;-)

Regards,
Heather

--
Heather Coppersmith
That's not right; that's not even wrong. -- Wolfgang Pauli

[beliavsky]

Skip Montanaro <sk**@pobox.com > wrote in message news:<ma******* *************** *************** *@python.org>.. .

beliavsky> Is there a more recent set of Python style guidelines than
beliavsky> PEP 8, "Style Guide for Python Code", by van Rossum and
beliavsky> Warsaw, at http://www.python.org/peps/pep-0008.html , which
beliavsky> is dated July 5, 2001?

Is there something missing you think should be there? There's no particular
reason a PEP needs to be continually updated. In particular, notions of
good Python style haven't changed a lot over the past ten years.

Skip

I am not qualified to say what should be in Python style guidelines. I
have now read the PEP 8 style guidelines and see that Python versions
up to 2.3 are covered. I think the Post-History date of July 5, 2001
is incorrect and should be updated.

[Michael Hudson]

be*******@aol.c om writes:

Skip Montanaro <sk**@pobox.com > wrote in message news:<ma******* *************** *************** *@python.org>.. .

beliavsky> Is there a more recent set of Python style guidelines than
beliavsky> PEP 8, "Style Guide for Python Code", by van Rossum and
beliavsky> Warsaw, at http://www.python.org/peps/pep-0008.html , which
beliavsky> is dated July 5, 2001?

Is there something missing you think should be there? There's no particular
reason a PEP needs to be continually updated. In particular, notions of
good Python style haven't changed a lot over the past ten years.

Skip

I am not qualified to say what should be in Python style guidelines. I
have now read the PEP 8 style guidelines and see that Python versions
up to 2.3 are covered. I think the Post-History date of July 5, 2001
is incorrect and should be updated.

How so? It hasn't been posted to comp.lang.pytho n since then, and
that's what the Post-History: records.

Cheers,
mwh

--
If I had wanted your website to make noise I would have licked
my finger and rubbed it across the monitor.
-- signature of "istartedi" on slashdot.org

[Josef Meile]

>>>>>a='test'

>if a.find('foo'):

... print "foo was found"
...
foo was found

a.find does not return a boolean, so that particular style guideline
does not apply.

I know, but I found this on the Zope source, which
means that there is people thinking that the False
on python includes negative values.

[Peter Hansen]

Josef Meile wrote:

>> a='test'
>> if a.find('foo'):
... print "foo was found"
...
foo was found

a.find does not return a boolean, so that particular style guideline
does not apply.

I know, but I found this on the Zope source, which
means that there is people thinking that the False
on python includes negative values.

I believe it's more likely they just forgot what find() did return, as
they were writing the code. I've done the same, thinking it was a
boolean, not thinking that it returned a negative but that negatives
were considered false.

-Peter

[Aahz]

In article <40********@pfa ff2.ethz.ch>,
Josef Meile <jm****@hotmail .com> wrote:

I agree, those are good guidelines, but I don't agree with:

- Don't compare boolean values to True or False using == (bool
types are new in Python 2.3):

No: if greeting == True:
Yes: if greeting:

What would happened if you do:

a='test'
if a.find('foo'):... print "foo was found"
...
foo was found

'foo' in 'test'

False
--
Aahz (aa**@pythoncra ft.com) <*> http://www.pythoncraft.com/

"Do not taunt happy fun for loops. Do not change lists you are looping over."
--Remco Gerlich, comp.lang.pytho n