I see the value of a class when two or more instances will be created,
but Python programmers regularly use a class when there will only be one
instance.
What is the benefit of this? It has a disadvantage of a whole lot of
"self."
being required everywhere, making the code less readable. Also, since a
strength of Python is rapid application development, it slows one down
to have to put in all those self.'s. The code seems much cleaner to me
without classes that have only one instance. Oh, also, all the methods
of this class will have to have the instance name prepended to them.
I would appreciate it if someone could explain the advantages of doing
this, or at least the sociological reasons why it occurs.
Mitchell Timin
--
"Many are stubborn in pursuit of the path they have chosen, few in
pursuit of the goal." - Friedrich Nietzsche http://annevolve.sourceforge.net is what I'm into nowadays.
Humans may write to me at this address: zenguy at shaw dot ca 34  4767 
On Ter 25 Mai 2004 21:43, Se******@SeeBel ow.Nut wrote: I see the value of a class when two or more instances will be created,
but Python programmers regularly use a class when there will only be one
instance.
What is the benefit of this? It has a disadvantage of a whole lot of
"self."
being required everywhere, making the code less readable. Also, since a
strength of Python is rapid application development, it slows one down
to have to put in all those self.'s. The code seems much cleaner to me
without classes that have only one instance. Oh, also, all the methods
of this class will have to have the instance name prepended to them.
I would appreciate it if someone could explain the advantages of doing
this, or at least the sociological reasons why it occurs.
How can you guarantee that such a code will never ever be used again,
anywhere?
It's easier to allow for code reuse from the beginning, IMHO.
--
Godoy. <go***@ieee.org >
On 2004-05-26, Se******@SeeBel ow.Nut <Se******@SeeBe low.Nut> wrote: I see the value of a class when two or more instances will be created, but
Python programmers regularly use a class when there will only be one
instance. What is the benefit of this?
What happens when down the line someone wants to use that code in
something that requires multiple instances?
--
Steve C. Lamb | I'm your priest, I'm your shrink, I'm your
PGP Key: 8B6E99C5 | main connection to the switchboard of souls.
-------------------------------+---------------------------------------------
On Wed, 26 May 2004 00:43:49 +0000, SeeBelow wrote: I see the value of a class when two or more instances will be created,
but Python programmers regularly use a class when there will only be one
instance.
What is the benefit of this? It has a disadvantage of a whole lot of
"self."
being required everywhere, making the code less readable. Also, since a
strength of Python is rapid application development, it slows one down
to have to put in all those self.'s. The code seems much cleaner to me
without classes that have only one instance. Oh, also, all the methods
of this class will have to have the instance name prepended to them.
I would appreciate it if someone could explain the advantages of doing
this, or at least the sociological reasons why it occurs.
Mitchell Timin
defining a class may be useful if you plan on making more instances down
the line. It's a good OO strategy. I do understand your dislike of 'self'.
It does seem like clutter. In my code, I shorten it to 's'. In ruby, class
variables are prefixed with an '@', which makes them easier to discern in
code, and it is easier than typing 'self'. I wish python had something
like that. I also think that having to specify the class variable in every
function definition is a bit silly. Ruby gets rid of that too.
--SegPhault
In article <40************ ***@shaw.ca>, Se******@SeeBel ow.Nut wrote: I see the value of a class when two or more instances will be created,
but Python programmers regularly use a class when there will only be one
instance.
What is the benefit of this? It has a disadvantage of a whole lot of
"self."
being required everywhere, making the code less readable. Also, since a
strength of Python is rapid application development, it slows one down
to have to put in all those self.'s. The code seems much cleaner to me
without classes that have only one instance. Oh, also, all the methods
of this class will have to have the instance name prepended to them.
I would appreciate it if someone could explain the advantages of doing
this, or at least the sociological reasons why it occurs.
Mitchell Timin
Typing "self" is a mechanical process which adds very little to the
development cost. Deciding which things to make classes and which not
to requires significant mental effort and does add cost. It's just
easier to make everything a class.
More than that, most times I've decided to not bother making something a
class because it was too simple, I've eventually added enough
functionality to it to change my mind and have to re-do things. That's
real cost. Much simplier and cheaper to just make it a class from the
get-go.
Ryan Paul <se*******@sbcg lobal.net> wrote: defining a class may be useful if you plan on making more instances down
the line. It's a good OO strategy. I do understand your dislike of 'self'.
It does seem like clutter. In my code, I shorten it to 's'.
Please don't do that. While it's true that the first parameter of a
class method can be named anything, the use of "self" is so
overwhelmingly ubiquitous it might as well be a standard. Using
anything else is just going to make your code more difficult for anybody
else to read and understand.
Typing is cheap. Thinking is expensive. And, yes Aahz, you can quote
me on that :-)
Roy Smith wrote:
In article <40************ ***@shaw.ca>, Se******@SeeBel ow.Nut wrote:
I see the value of a class when two or more instances will be created,
but Python programmers regularly use a class when there will only be one
instance.
What is the benefit of this? It has a disadvantage of a whole lot of
"self."
being required everywhere, making the code less readable. Also, since a
strength of Python is rapid application development, it slows one down
to have to put in all those self.'s. The code seems much cleaner to me
without classes that have only one instance. Oh, also, all the methods
of this class will have to have the instance name prepended to them.
I would appreciate it if someone could explain the advantages of doing
this, or at least the sociological reasons why it occurs.
Mitchell Timin
Typing "self" is a mechanical process which adds very little to the
development cost. Deciding which things to make classes and which not
to requires significant mental effort and does add cost. It's just
easier to make everything a class.
Even easier is not to make anything a class unless there will be two or
more instances of it. I still don't get what advantage making a class
buys for you.
More than that, most times I've decided to not bother making something a
class because it was too simple, I've eventually added enough
functionality to it to change my mind and have to re-do things. That's
real cost. Much simplier and cheaper to just make it a class from the
get-go.
Why does greater functionality make a class desireable, if there won't
be multiple instances created?
Other people have mentioned "code reuse". Again I don't see how a class
helps to make code reusable. I find methods in a class more difficult
to reuse than simple function definitions. (unless there are multiple
instances.)
Mitchell Timin
--
"Many are stubborn in pursuit of the path they have chosen, few in
pursuit of the goal." - Friedrich Nietzsche http://annevolve.sourceforge.net is what I'm into nowadays.
Humans may write to me at this address: zenguy at shaw dot ca
In article <40************ ***@shaw.ca>, Se******@SeeBel ow.Nut wrote: More than that, most times I've decided to not bother making something a
class because it was too simple, I've eventually added enough
functionality to it to change my mind and have to re-do things. That's
real cost. Much simplier and cheaper to just make it a class from the
get-go.
Why does greater functionality make a class desireable, if there won't
be multiple instances created?
For me, it's more about encapsulation than code re-use. If I've got a
bunch of functions which operate on a collection of data, to me that
says "object", which in Python (and most OOPL's) implies "class".
Bundling it up into a class lets me think about it as a unit. Each
class is a convenient thought unit for design and testing, and also for
understanding somebody else's code.
I don't think there's a need to be dogmatic about it. It's just what I
find is a natural way to break a program down into smaller pieces you
can get your brain around one piece at a time.
Roy Smith wrote:
In article <40************ ***@shaw.ca>, Se******@SeeBel ow.Nut wrote:
More than that, most times I've decided to not bother making something a
class because it was too simple, I've eventually added enough
functionality to it to change my mind and have to re-do things. That's
real cost. Much simplier and cheaper to just make it a class from the
get-go.
Why does greater functionality make a class desireable, if there won't
be multiple instances created?
For me, it's more about encapsulation than code re-use. If I've got a
bunch of functions which operate on a collection of data, to me that
says "object", which in Python (and most OOPL's) implies "class".
OK, that makes some sense - to associate certain data and code items and
separate them from other code and data. Wouldn't that purpose be served
even better by putting them into a different file, and not bother with a
class?
Bundling it up into a class lets me think about it as a unit. Each
class is a convenient thought unit for design and testing, and also for
understanding somebody else's code.
I don't think there's a need to be dogmatic about it. It's just what I
find is a natural way to break a program down into smaller pieces you
can get your brain around one piece at a time.
--
"Many are stubborn in pursuit of the path they have chosen, few in
pursuit of the goal." - Friedrich Nietzsche http://annevolve.sourceforge.net is what I'm into nowadays.
Humans may write to me at this address: zenguy at shaw dot ca
<Se******@SeeBe low.Nut> wrote in message news:40******** *******@shaw.ca ... I see the value of a class when two or more instances will be created,
but Python programmers regularly use a class when there will only be one
instance.
What is the benefit of this? It has a disadvantage of a whole lot of
"self."
being required everywhere, making the code less readable. Also, since a
strength of Python is rapid application development, it slows one down
to have to put in all those self.'s. The code seems much cleaner to me
without classes that have only one instance. Oh, also, all the methods
of this class will have to have the instance name prepended to them.
I'm only aware of one domain (interactive fiction) where it is really
common to have single instance classes. That's served by a number
of special purpose languages (Inform, TADS and Hugo spring to
mind). Your example (of single use classes in a UI context) seems
to be a bit contrived. I've usually found that I could get quite a bit
of code reuse out of UI classes simply by thinking the problems
through.
Granted, single use classes aren't uncommon, but instances of
other classes are much more common in most programs. In
Python, there are a number of ways of getting singletons without
very much extra effort.
I would appreciate it if someone could explain the advantages of doing
this, or at least the sociological reasons why it occurs.
Both have their uses. The class / instance dicotomy comes from
the earliest days of object oriented programming, and experiments
with classless languages (see the Prothon stuff currently going on,
also the IO language) have never been very compelling. A lot of
people (which include me) think that it's much to easy to get sloppy
with that paradigm.
The other thing to understand is that in most OO languages a
class is a declaration: it does not appear in the actual object
program other than as a framework for the instances that are
created. Python is one of the few languages where classes are
first class objects.
John Roth
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