Duck Typing

**John Roth** · Jul 18 '05, 02:36 AM

Re: Duck Typing

<srijit@yahoo.c om> wrote in message
news:221d8dbe.0 309160101.4a09f 2ad@posting.goo gle.com...[color=blue]
> Hello All,
> I have been seeing this term "duck typing" for quite sometime now. It
> will be nice if one of us can give an example in Python demonstrating
> duck typing and/or link to some Python references.[/color]

Why in the world would anyone want to do such a thing? I hadn't
heard the term until you just brought it up, so a quick Google defined
it. AFAICT, it's simply a cute name that's applied to a very common
technique in languages that don't use static typing.

In other words, if you need a file-like object, and someone passes
you an object, your options are either to just use it (and handle the
exceptions if it doesn't really support the proper interface) or use
reflection to see if it has methods with the proper name and number
of parameters, and then be prepared to handle the exceptions when
they don't do what you expect.

Six of one, half a dozen of the other.

John Roth
[color=blue]
>
> Regards,
> Srijit[/color]

**Irmen de Jong** · Jul 18 '05, 02:36 AM

Re: Duck Typing

srijit@yahoo.co m wrote:[color=blue]
> I have been seeing this term "duck typing" for quite sometime now. It
> will be nice if one of us can give an example in Python demonstrating
> duck typing and/or link to some Python references.[/color]

Is this helpful: http://www.razorvine.net/python/PythonLanguageConcepts
(paragraph 'dynamic typing') ?

--Irmen de Jong

**Oren Tirosh** · Jul 18 '05, 02:36 AM

Re: Duck Typing

On Tue, Sep 16, 2003 at 02:01:18AM -0700, srijit@yahoo.co m wrote:[color=blue]
> Hello All,
> I have been seeing this term "duck typing" for quite sometime now. It
> will be nice if one of us can give an example in Python demonstrating
> duck typing and/or link to some Python references.[/color]

class Duck:
def quack(self):
print "Quack!"

class MeWearingSillyD uckOutfit:
def quack(self):
print "ummm... Quack!"

def make_it_quack(o bj):
obj.quack()

a = Duck()
b = MeWearingSillyD uckOutfit()
make_it_quack(a )
make_it_quack(b )

**Steve Holden** · Jul 18 '05, 02:36 AM

Re: Duck Typing

"Oren Tirosh" <oren-py-l@hishome.net> wrote ...[color=blue]
> On Tue, Sep 16, 2003 at 02:01:18AM -0700, srijit@yahoo.co m wrote:[color=green]
> > Hello All,
> > I have been seeing this term "duck typing" for quite sometime now. It
> > will be nice if one of us can give an example in Python demonstrating
> > duck typing and/or link to some Python references.[/color]
>
> class Duck:
> def quack(self):
> print "Quack!"
>
> class MeWearingSillyD uckOutfit:
> def quack(self):
> print "ummm... Quack!"
>
> def make_it_quack(o bj):
> obj.quack()
>
> a = Duck()
> b = MeWearingSillyD uckOutfit()
> make_it_quack(a )
> make_it_quack(b )
>[/color]

exquacktly [ducks and runs]

regards
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/pwp/

**Peter Hansen** · Jul 18 '05, 02:37 AM

Re: Duck Typing

Steve Holden wrote:[color=blue]
>
> exquacktly [ducks and runs][/color]
^^^^^

Steve, did you even _know_ you did this? You're sick!

-Peter :-)

**Irmen de Jong** · Jul 18 '05, 02:37 AM

Re: Duck Typing

Peter Hansen wrote:[color=blue]
> Steve Holden wrote:
>[color=green]
>>exquacktly [ducks and runs][/color]
>
> ^^^^^
>
> Steve, did you even _know_ you did this? You're sick!
>
> -Peter :-)[/color]

people are currently turning their heads to me to see why I
suddenly bursted out in laughter :-)

--Irmen

**Steve Holden** · Jul 18 '05, 02:37 AM

Re: Duck Typing

"Peter Hansen" <peter@engcorp. com> wrote in message
news:3F6732DB.F 31A954E@engcorp .com...[color=blue]
> Steve Holden wrote:[color=green]
> >
> > exquacktly [ducks and runs][/color]
> ^^^^^
>
> Steve, did you even _know_ you did this? You're sick!
>
> -Peter :-)[/color]

Aah, I see, you think I'm stupid.

Of course I knew - without the bracketed afterthought it would hardly have
been worth posting.

I'll send you a bill ;-)

regards
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/pwp/

**Peter Hansen** · Jul 18 '05, 02:37 AM

Re: Duck Typing

Steve Holden wrote:[color=blue]
>
> "Peter Hansen" <peter@engcorp. com> wrote in message
> news:3F6732DB.F 31A954E@engcorp .com...[color=green]
> > Steve Holden wrote:[color=darkred]
> > >
> > > exquacktly [ducks and runs][/color]
> > ^^^^^
> >
> > Steve, did you even _know_ you did this? You're sick!
> >
> > -Peter :-)[/color]
>
> Aah, I see, you think I'm stupid.[/color]

No, I just knew Irmen was asleep at his keyboard. ;-)
[color=blue]
> Of course I knew - without the bracketed afterthought it would hardly have
> been worth posting.
>
> I'll send you a bill ;-)[/color]

If you make it a twenty, would that be a "sawduck"?

-Peter

**Oren Tirosh** · Jul 18 '05, 02:37 AM

Re: Duck Typing

On Tue, Sep 16, 2003 at 03:47:11PM +0000, Steve Holden wrote:[color=blue]
> "Oren Tirosh" <oren-py-l@hishome.net> wrote ...[color=green]
> > On Tue, Sep 16, 2003 at 02:01:18AM -0700, srijit@yahoo.co m wrote:[color=darkred]
> > > Hello All,
> > > I have been seeing this term "duck typing" for quite sometime now. It
> > > will be nice if one of us can give an example in Python demonstrating
> > > duck typing and/or link to some Python references.[/color]
> >
> > class Duck:
> > def quack(self):
> > print "Quack!"
> >
> > class MeWearingSillyD uckOutfit:
> > def quack(self):
> > print "ummm... Quack!"
> >
> > def make_it_quack(o bj):
> > obj.quack()
> >
> > a = Duck()
> > b = MeWearingSillyD uckOutfit()
> > make_it_quack(a )
> > make_it_quack(b )
> >[/color]
>
> exquacktly [ducks and runs][/color]

class Run:
def quack(self):
print "QUACK!"

ducks = [Duck() for i in range(10)]
runs = [Run() for i in range(10)]
apply(make_it_q uack, ducks+runs)

Oren

**Steve Holden** · Jul 18 '05, 02:39 AM

Re: Duck Typing

"Peter Hansen" <peter@engcorp. com> wrote in message
news:3F6749B6.7 4601D54@engcorp .com...[color=blue]
> Steve Holden wrote:[color=green]
> >
> > "Peter Hansen" <peter@engcorp. com> wrote in message
> > news:3F6732DB.F 31A954E@engcorp .com...[color=darkred]
> > > Steve Holden wrote:
> > > >
> > > > exquacktly [ducks and runs]
> > > ^^^^^
> > >
> > > Steve, did you even _know_ you did this? You're sick!
> > >
> > > -Peter :-)[/color]
> >
> > Aah, I see, you think I'm stupid.[/color]
>
> No, I just knew Irmen was asleep at his keyboard. ;-)
>[color=green]
> > Of course I knew - without the bracketed afterthought it would hardly[/color][/color]
have[color=blue][color=green]
> > been worth posting.
> >
> > I'll send you a bill ;-)[/color]
>
> If you make it a twenty, would that be a "sawduck"?
>[/color]

You'll never beat me at this game. After all, I did write "Web Programming
in Python" ;-)

regards
--
Steve Holden http://www.holdenweb.com/
Python Web Programming http://pydish.holdenweb.com/pwp/

Duck Typing

Duck Typing

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