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explicit self revisited

The Python FAQ 1.4.5 gives 3 reasons for explicit self (condensed version):

1. Instance variables can be easily distinguished from local variables.

2. A method from a particular class can be called as
baseclass.metho dname(self, <argument list>).

3. No need for declarations to disambiguate assignments to local/instance
variables.

All these reasons are valid and retained by the following suggestion: let
self be represented by the dot, e.g. replace

class someTest(unitte st.TestCase):
def setUp(self):
self.ly = yList()
self.m1 = self.ly[0].message
self.m2 = self.ly[1].message
self.m3 = self.ly[2].message

def testList(self):
self.assertEqua l(len(self.ly), 3)
self.assertEqua l(self.m1),"Ho" )
self.assertEqua l(self.m2),"HoH o")
self.assertEqua l(self.m3),"HoH oHo")

by

class x(unittest.Test Case):
def .setUp():
.ly = yList()
.m1 = .ly[0].message
.m2 = .ly[1].message
.m3 = .ly[2].message

def .testList():
.assertEqual(le n(.ly),3)
.assertEqual(.m 1),"Ho")
.assertEqual(.m 2),"HoHo")
.assertEqual(.m 3),"HoHoHo")

Methods could still be referenced e.g. as x.testList(some Instance).
The current self syntax could still be valid (for backward compatibility.)
Advantages of the new syntax:

1. Enhanced readability, less verbosity

2. Unambiguous: no need to tell newbies that a virtuous pythoneer
has to stick to self instead of abbreviate it as s.

3. One argument less for "Python OO bolted on" propaganda.

The second reason is the most important for me. I consider syntax control
by a code of conduct as lame.

The "leading dot" syntax could have further advantages:

class x(object):
a = "" # static variable
.b = 0 # instance variable

This could replace parameterless __init__ methods. Methods without leading
dots could be considered static without a staticmethod decorator. For
backward compatibility this behaviour should be explicitly activated e.g. by
__autostatic__ = true.

What do you think?

--
Regards/Gruesse,

Peter Maas, Aachen
E-mail 'cGV0ZXIubWFhc0 B1dGlsb2cuZGU=\ n'.decode('base 64')
Nov 11 '06 #1
24 2286
Peter Maas wrote:
What do you think?
cannot all you clueless trolls who cannot think of a single useful thing
to contribute to Python start your own newsgroup?

</F>

Nov 11 '06 #2
cannot all you clueless trolls who cannot think of a single useful thing
to contribute to Python start your own newsgroup?
and before anyone complains; please note that they're working through

http://www.effbot.org/pyfaq/design-index.htm

one article at a time. who's going to be the first one to argue that
Python needs a goto statement ?

</F>

Nov 11 '06 #3

Fredrik Lundh wrote:
Fredrik Lundh wrote:
cannot all you clueless trolls who cannot think of a single useful thing
to contribute to Python start your own newsgroup?

and before anyone complains; please note that they're working through

http://www.effbot.org/pyfaq/design-index.htm
That site is a bunch of FUD -
The explicit self is there simply because OOP was tacked onto python as
an afterthought.
Why not just be honest about it. It's too late to change Python's
syntax. It just means a little extra typing. If it really bothers
someone, use "s" instead of "self" or else use Ruby.

Nov 11 '06 #4
Doug (Holton?) wrote:
>and before anyone complains; please note that they're working through

http://www.effbot.org/pyfaq/design-index.htm

That site is a bunch of FUD -
the official FAQ is a bunch of FUD? are you sure you know what FUD means?

</F>

Nov 11 '06 #5

DougThe explicit self is there simply because OOP was tacked onto
Dougpython as an afterthought.

Got a reference to support that claim?

Skip
Nov 11 '06 #6
On Sat, 11 Nov 2006 18:09:59 -0600, skip wrote:
>
DougThe explicit self is there simply because OOP was tacked onto
Dougpython as an afterthought.

Got a reference to support that claim?
Of course not, since it is a classic example of trolling.

By comparison, the way I read the Original Poster, he was sincere if
misguided -- but Doug's bullshit response is a typical attempt to throw
petrol on an already hot situation.
--
Steven.

Nov 12 '06 #7
Dennis Lee Bieber wrote:
>one article at a time. who's going to be the first one to argue that
Python needs a goto statement ?
Especially since there is a comefrom <G>
ah, good point. I've updated the FAQ.

</F>

Nov 12 '06 #8
On Sat, 11 Nov 2006 22:39:37 +0100, Peter Maas wrote:

[snip]
let self be represented by the dot, e.g. replace

class someTest(unitte st.TestCase):
def setUp(self):
self.ly = yList()
self.m1 = self.ly[0].message
self.m2 = self.ly[1].message
self.m3 = self.ly[2].message
by

class x(unittest.Test Case):
def .setUp():
.ly = yList()
.m1 = .ly[0].message
.m2 = .ly[1].message
.m3 = .ly[2].message
On the assumption that Peter was sincere, and not trolling, I thought I'd
make a point-by-point response, but then X crashed and took my post with
it. So here's the brief version.

Implicit self will never be used for Python, because it is redundant so
long as there is a need for explicit self, and there is a need for
explicit self because there are a number of basic, dare I say
*fundamental* programming techniques that require an explicit self.

For example, delegation.

class MyClass(Parent) :
def method(self, arg):
Parent.method(s elf, arg)
# what are you going to write? Parent.method(, arg) maybe?

Here's another fundamental technique that implicit self breaks.

class MyList(list):
def __iadd__(self, other):
# in-place addition
other = transform(other ) # do something to the argument
super(MyList, self).__iadd__( other) # call the superclass
# could be written .__class__.__ia dd__(other)
# BUT be aware the semantics are NOT the same!
return self # and return the suitably modified instance

You can't explicitly return the instance unless you have an explicit name
for it. (And if you are thinking of creating more magic syntax that
implicitly returns self, just don't bother.)

Even more fundamentally, any time you need to pass the instance to a
function, you need an explicit self. (Delegation is a special case of this.)

def __str__(self):
# I like semicolons and dislike square brackets.
return ';'.join(self)

--
Steven.

Nov 12 '06 #9

Fredrik Lundh wrote:
Doug wrote:
>>
Fredrik Lundh wrote:
>>Fredrik Lundh wrote:
cannot all you clueless trolls who cannot think of a single useful thing
to contribute to Python start your own newsgroup?
>>and before anyone complains; please note that they're working through
>> http://www.effbot.org/pyfaq/design-index.htm

That site is a bunch of FUD -
The explicit self is there simply because OOP was tacked onto python as
an afterthought.
Why not just be honest about it. It's too late to change Python's
syntax. It just means a little extra typing. If it really bothers
someone, use "s" instead of "self" or else use Ruby.

the official FAQ is a bunch of FUD? are you sure you know what FUD means?

</F>
You idiot. Putting the word "official" in front of something doesn't
mean it can't be FUD. Especially when it is written by people such as
yourself. Have you not paid attention to anything happening in
politics around the world during your lifetime?
And yes, actually, the dash after FUD was where I was going to link to
a definition of FUD to show I really meant to use that term. It
doesn't appear that you believe anything that isn't on your own effbot
site, however.

Nov 12 '06 #10

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