Re: [1,2,3] exactly same as [1,2,3,] ?
In article <[EMAIL PROTECTED]>,
Fredrik Lundh <[EMAIL PROTECTED]> wrote:
> Roy Smith wrote:
>
> > Yowza, you're right (at least for the one case I tried). This must be a
> > new development (where "new development" is defined as, "It wasn't legal in
> > the original K&R C I learned when I was a pup").
>
> the C 89 grammar appears to be:
>
> initializer:
> assignment-expression
> { initializer-list }
> { initializer-list , }
>
> initializer-list:
> designation-opt initializer
> initializer-list , designation-opt initializer
>
> so a trailing comma has been allowed for around twenty years.
>
>
C89 came out about 10 years after I first learned C :-)
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Re: [1,2,3] exactly same as [1,2,3,] ?
Roy Smith wrote:
Yowza, you're right (at least for the one case I tried). This must be a
new development (where "new development" is defined as, "It wasn't legal in
the original K&R C I learned when I was a pup").
the C 89 grammar appears to be:
initializer:
assignment-expression
{ initializer-list }
{ initializer-list , }
initializer-list:
designation-opt initializer
initializer-list , designation-opt initializer
so a trailing comma has been allowed for around twenty years.
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Re: [1,2,3] exactly same as [1,2,3,] ?
Steven D'Aprano wrote:
On Thu, 28 Aug 2008 16:28:03 -0700, Paul McNett wrote:
[EMAIL PROTECTED] wrote:
x=[1,2,3]
and
x=[1,2,3,]
are exactly the same, right?
When confronted with this type of question, I ask the interpreter:
{{{
mac:~ pmcnett$ python
Python 2.5.2 (r252:60911, Feb 22 2008, 07:57:53) [GCC 4.0.1 (Apple
Computer, Inc. build 5363)] on darwin Type "help", "copyright",
"credits" or "license" for more information.
>>> [1,2,3] == [1,2,3,]
True
}}}
Putting on my pedantic hat...
In this case you're right about the two lists being the same, and I'm a
great believer in checking things in the interactive interpreter, but you
need to take care. Just because two objects compare as equal doesn't
*necessarily* mean they are the same:
True.
1.0 == 1
True
1.0 == decimal.Decimal('1.0')
False
1.0 == float(decimal.Decimal('1.0'))
True
These are comparing different types.
collections.defaultdict(999) == {}
True
I try this and get:
TypeError: first arument must be callable
Paul
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Re: [1,2,3] exactly same as [1,2,3,] ?
In article <[EMAIL PROTECTED]>,
Grant Edwards <[EMAIL PROTECTED]> wrote:
> On 2008-08-29, Roy Smith <[EMAIL PROTECTED]> wrote:
>
> > Exactly. This is one of those little pieces of syntactic
> > sugar which makes python so nice to work with. The
> > alternative is (in C, for example) abominations like this:
> >
> > const char* l[] = {"foo"
> > , "bar"
> > , "baz"
> > };
> >
> > and even those are not quite as good because you still have to
> > special-case the first entry.
>
> It's probably a spec violation, but I've never seen a C
> compiler that objected to a comma after the last item in an
> initializer list. (At least not at the warning levels I use,
> which tend to be on the picky side.)
Yowza, you're right (at least for the one case I tried). This must be a
new development (where "new development" is defined as, "It wasn't legal in
the original K&R C I learned when I was a pup").
Still, I have seem people do that in code.
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Re: [1,2,3] exactly same as [1,2,3,] ?
On Thu, 28 Aug 2008 16:28:03 -0700, Paul McNett wrote:
> [EMAIL PROTECTED] wrote:
>> x=[1,2,3]
>> and
>> x=[1,2,3,]
>>
>> are exactly the same, right?
>
> When confronted with this type of question, I ask the interpreter:
>
> {{{
> mac:~ pmcnett$ python
> Python 2.5.2 (r252:60911, Feb 22 2008, 07:57:53) [GCC 4.0.1 (Apple
> Computer, Inc. build 5363)] on darwin Type "help", "copyright",
> "credits" or "license" for more information.
> >>> [1,2,3] == [1,2,3,]
> True
> }}}
Putting on my pedantic hat...
In this case you're right about the two lists being the same, and I'm a
great believer in checking things in the interactive interpreter, but you
need to take care. Just because two objects compare as equal doesn't
*necessarily* mean they are the same:
>>> 1.0 == 1
True
>>> 1.0 == decimal.Decimal('1.0')
False
>>> 1.0 == float(decimal.Decimal('1.0'))
True
>>> collections.defaultdict(999) == {}
True
--
Steven
--
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Re: [1,2,3] exactly same as [1,2,3,] ?
On 2008-08-29, Roy Smith <[EMAIL PROTECTED]> wrote:
> Exactly. This is one of those little pieces of syntactic
> sugar which makes python so nice to work with. The
> alternative is (in C, for example) abominations like this:
>
> const char* l[] = {"foo"
> , "bar"
> , "baz"
> };
>
> and even those are not quite as good because you still have to
> special-case the first entry.
It's probably a spec violation, but I've never seen a C
compiler that objected to a comma after the last item in an
initializer list. (At least not at the warning levels I use,
which tend to be on the picky side.)
--
Grant Edwards grante Yow! There's enough money
at here to buy 5000 cans of
visi.comNoodle-Roni!
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Re: [1,2,3] exactly same as [1,2,3,] ?
Terry Reedy <[EMAIL PROTECTED]> wrote:
> Yes, so you can write something like either your second example or
>
> l = [
>kjasldfjs,
>kjsalfj,
>ksjdflasj,
> ]
>
> and insert items without worrying about leaving out the comma (less of a
> problem with 'horizontal' list), or delete the last line and not have to
> worry about deleting the comma on the line before.
Exactly. This is one of those little pieces of syntactic sugar which makes
python so nice to work with. The alternative is (in C, for example)
abominations like this:
const char* l[] = {"foo"
, "bar"
, "baz"
};
and even those are not quite as good because you still have to special-case
the first entry.
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Re: [1,2,3] exactly same as [1,2,3,] ?
[EMAIL PROTECTED] wrote: x=[1,2,3] and x=[1,2,3,] are exactly the same, right? I'm generating some python data, and it's less error prone to not treat the last element specially, but I want to be sure I'm generating an equivalent data structure. Many TIA! Mark >>> x=[1,2,3,] >>> repr(x) [1,2,3] -- http://mail.python.org/mailman/listinfo/python-list
Re: [1,2,3] exactly same as [1,2,3,] ?
[EMAIL PROTECTED] wrote: x=[1,2,3] and x=[1,2,3,] are exactly the same, right? Yes, so you can write something like either your second example or l = [ kjasldfjs, kjsalfj, ksjdflasj, ] and insert items without worrying about leaving out the comma (less of a problem with 'horizontal' list), or delete the last line and not have to worry about deleting the comma on the line before. -- http://mail.python.org/mailman/listinfo/python-list
Re: [1,2,3] exactly same as [1,2,3,] ?
James Mills wrote: I must point out though that although they contain the same elements/data, they are not the same object/instance. True, but the OP wanted equality: > I want to be > sure I'm generating an equivalent data structure. Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: [1,2,3] exactly same as [1,2,3,] ?
On Fri, Aug 29, 2008 at 9:28 AM, Paul McNett <[EMAIL PROTECTED]> wrote:
> When confronted with this type of question, I ask the interpreter:
>
> {{{
> mac:~ pmcnett$ python
> Python 2.5.2 (r252:60911, Feb 22 2008, 07:57:53)
> [GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin
> Type "help", "copyright", "credits" or "license" for more information.
[1,2,3] == [1,2,3,]
> True
> }}}
I must point out though that although they contain
the same elements/data, they are not the same
object/instance.
{{{
#!python
>>> x = [1, 2, 3]
>>> y = [1, 2, 3]
>>> id(x)
3083095148L
>>> id(y)
3082953324L
>>> x == y
True
}}}
If you view the documentation for a list:
{{{
#!sh
$ pydoc list
}}}
list's have an __eq__ that is used to compare the
equality of 2 lists.
cheers
James
--
--
-- "Problems are solved by method"
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Re: [1,2,3] exactly same as [1,2,3,] ?
Paul McNett <[EMAIL PROTECTED]> wrote: > When confronted with this type of question, I ask the interpreter: > >>> [1,2,3] == [1,2,3,] > True Well I guess that's a pretty authoritative answer... thanks! -- Mark Harrison Pixar Animation Studios -- http://mail.python.org/mailman/listinfo/python-list
Re: [1,2,3] exactly same as [1,2,3,] ?
[EMAIL PROTECTED] wrote:
x=[1,2,3]
and
x=[1,2,3,]
are exactly the same, right?
When confronted with this type of question, I ask the interpreter:
{{{
mac:~ pmcnett$ python
Python 2.5.2 (r252:60911, Feb 22 2008, 07:57:53)
[GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> [1,2,3] == [1,2,3,]
True
}}}
Paul
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[1,2,3] exactly same as [1,2,3,] ?
x=[1,2,3] and x=[1,2,3,] are exactly the same, right? I'm generating some python data, and it's less error prone to not treat the last element specially, but I want to be sure I'm generating an equivalent data structure. Many TIA! Mark -- Mark Harrison Pixar Animation Studios -- http://mail.python.org/mailman/listinfo/python-list
