[Baypiggies] Frequently Argued Objections

[Shannon -jj Behrens]

Wait a second, how did we get this far without the normal objections?

* Python isn't stackless.

Ok, I'll just shut up ;)

* Python doesn't have tail call optimization.

I think the thinking is that for loops are more readable than using
recursion all over the place.

* Python doesn't have a match statement like ML.

This is probably because there's no obvious way to make the syntax work.

* Python differentiates expressions and statements.

This is because Guido thinks that if you allow all statements to be
expressions, you get weird situations like defining a 100 line
function as a parameter in the middle of calling another function.
Looking at modern JavaScript, I would agree with him.  However,
because of this, you can't write:

a = if b:
           f()
       else:
           g()
print a

I know it's sometimes frustrating, but I think Guido was right to err
on the side of readability.

* No one has brought up the lack of private variables either.

Python doesn't assume that you're an untrustable moron ;)

* Python is a half- at ss Lisp with too few parenthesis.

Actually, Python takes many of the good parts of Lisp, and makes them
more readable ;)

Happy Hacking!
-jj

On Tue, Jun 24, 2008 at 5:03 AM, Shannon -jj Behrens <jjinux at gmail.com> wrote:
> Your post did bring up one thing I do like about Ruby.  It has a more
> defined notion of class scope at class definition time.  If Python had
> that, I could do something like:
>
> class B(A):
>    ...
>    if hasattr(B, 'foo'):
>        ...
>
> That's not possible now, because B doesn't exist until the class is
> finished being defined.  There are workarounds.  It's not a big deal.
> I'm just saying ;)
>
> -jj
>
> On Mon, Jun 23, 2008 at 4:35 PM, Warren Stringer <warren at muse.com> wrote:
>> Ok, so "var=x" instantiates a static var x, yes? For example:
>> class a(object):
>>     b=1
>>     # self.b does not work here
>>     def __init__(self):
>>         self.b=2 # so declare it in the constructor
>>     def f(self):
>>         b=3
>>         print a.b, self.b, b
>>         b=b+1
>> i=a()
>> i.f() # => prints 1 2 3
>> a.b=4
>> i.f() # => prints 4 2 3
>> j=a()
>> j.f() # => prints 4 2 3
>> a.b=5 # will change for i and j
>> i.f() # => prints 5 2 3
>> j.f() # => prints 5 2 3
>> i.b=6 #changes self.b
>> i.f() # => prints 5 6 3
>> j.f() # = prints 2 6 3
>>
>>
>>
>> So, the ambiguity is that
>>
>>     whatever=a() will instantiate b=1 once, whereas
>>
>>     whatever.f() will instantiate b=3 always
>>
>>
>> Must keep track that
>>     a.b behaves differently from i.b, since
>>     i.b=6 implicitly passes self,
>>         somewhat akin to i.self.b, tho not quite
>>          (how would one express as internal dictionaries?)
>> As stated about @var, in Ruby:  "but conceptually bends Occam's razor -- it
>> makes the language introduce one more rule"
>> One may make the case that examples for b=1, b=3, a.b=5, i.b=6 also
>> introduce more rules.
>> This is what confused me the most, when learning Python. I have heard
>> similar objections. I have seen plenty of questions posted about this
>> problem and have seen many replies posted that essentially say "oh no, not
>> THAT question again."
>> There are several methods of dealing with objections:
>> 1) ignore it by calling it whining
>> a) and hope the whiners go away
>> 2) acknowledge the problem
>> a) show how it solves a bigger problem
>> b) show how a fix would create new problems
>> 3) eliminate the source of the problem
>> a) without creating new problems
>>
>> Guess which methods increase the popularity/longevity of a product? Since 3)
>> is not going to happen for self, I would suggest 2) over 1).
>> \~/
>> On Jun 23, 2008, at 8:40 AM, Alex Martelli wrote:
>>
>> On Mon, Jun 23, 2008 at 7:41 AM, Warren Stringer <warren at muse.com> wrote:
>>   ...
>>
>> My guess is that:
>>
>>       1)  9 times out of 10 the var in self.var is blindingly obvious,
>>
>>       2) 99 times out of 100 it is obvious after a 10 second search,
>>
>> I think that there are way more than 1 in 100 uses even just for the
>> simplest example that shows this guess to be unfounded: "self.var = x"
>> which would allowed to become "var = x"  under a deleterious "implicit
>> self" rule.
>>
>> Right now, "var = x" sets a local variable in the method, "self.var =
>> x" sets an instance variable: zero ambiguity, zero chances for error,
>> zero problems -- well let's say epsilon problems rather than zero,
>> because there IS the issue of having to listen to whines against
>> "mandatory explicit self";-).
>>
>> There are good ways and bad ways to address this issue during language
>> design. The best way -- as in Modula-3, Python, Perl-5, Ruby -- is to
>> explicitly mark instance variables (self.var in Modula-3 and Python,
>> $self->{var} in Perl-5, @self in Ruby); a somewhat inferior way -- as
>> in Squeak -- is to give up some of the language's dynamic nature by
>> forcing variables to be declared; a worse way would be to break
>> symmetry by using the explicit mark in assignment but not in
>> reference.
>>
>> The very worst way is shown by Javascript's "with" statement -- within
>> a Javascript "with zap", the meaning of "zop = 23" is essentially
>> unguessable as it depends on whether zap already did have a zop
>> attribute (in which case it rebinds it) or not (in which case it binds
>> a global variable -- unless there was an earlier declaration of "var
>> zop" in this function, in which case it binds the local variable
>> instead) -- a mix of forced declaration and blind guessing that good
>> books on Javascript (e.g. the short and useful "Javascript, the good
>> parts") strive to convince the reader to never, ever use that accursed
>> statement.
>>
>> Within the "explicit mark" camp, Ruby's "@var" is typographically
>> concise but conceptually bends Occam's razor -- it makes the language
>> introduce one more rule (on the meaning of a "@" prefix) where the
>> choice that Python took from Modula-3 just reuses an existing rule
>> (whatever.var means exactly the same in all cases, whether "whatever"
>> is "self" or something other than "self" -- no special cases, no extra
>> rules).
>>
>>
>> Alex
>>
>>
>>
>
>
>
> --
> It's a walled garden, but the flowers sure are lovely!
> http://jjinux.blogspot.com/
>



-- 
It's a walled garden, but the flowers sure are lovely!
http://jjinux.blogspot.com/