Re: Official definition of call-by-value (Re: Finding the instance reference...)

On 2008-11-20, greg <[EMAIL PROTECTED]> wrote: > Antoon Pardon wrote: > >> You are changing your argument. In a follow up you >> made the point that call by value should be as it >> was intended by the writers of the algol 60 report. > > No, I was countering the argument that "call by value" > is s

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, 23 Nov 2008 09:24:05 -0600, Derek Martin wrote: > On Tue, Nov 18, 2008 at 09:23:30AM +, Steven D'Aprano wrote: >> > How I can answer the question, "are the objects a and b the same or >> > different"? I can look at every aspect of each object, looking for >> > something that is differe

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Derek Martin wrote: [some stuff, followed by about 32k of unnecessarily quoted crap] It would be helpful if you'd take the time to trim your replies appropriately. regards Steve -- Steve Holden+1 571 484 6266 +1 800 494 3119 Holden Web LLC http://www.holdenweb.com/ -- ht

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Tue, Nov 18, 2008 at 09:23:30AM +, Steven D'Aprano wrote: > > How I can answer the question, "are the objects a and b the same or > > different"? I can look at every aspect of each object, looking for > > something that is different. > > Well, sure, if you care *that much* about potentially

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Aaron Brady <[EMAIL PROTECTED]> writes: > Truth and clarity are not tired of this thread. This is such a marvellously economic way of putting it, it's poetic! -- Arnaud -- http://mail.python.org/mailman/listinfo/python-list

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 22, 8:40 am, Joe Strout <[EMAIL PROTECTED]> wrote: > On Nov 22, 2008, at 4:08 AM, Aaron Brady wrote: > > > Furthermore, to apply c-b-v to Python, you have to > > introduce the concept of pointers, which is ostensibly non-native for > > human programmers. > > Not necessarily "pointers" per se

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 22, 2008, at 4:08 AM, Aaron Brady wrote: Furthermore, to apply c-b-v to Python, you have to introduce the concept of pointers, which is ostensibly non-native for human programmers. Not necessarily "pointers" per se -- any type of object references will do, and yes, Python has those in

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 21, 8:53 pm, greg <[EMAIL PROTECTED]> wrote: > Aaron Brady wrote: > > Call-by-value has other characteristics that Python does not > > meet. > > The designers of most other dynamic languages don't > seem to share that opinion, since they use the term > call-by-value just as though it *does*

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Aaron Brady wrote: Call-by-value has other characteristics that Python does not meet. The designers of most other dynamic languages don't seem to share that opinion, since they use the term call-by-value just as though it *does* mean call- by-assignment and nothing more. -- Greg -- http://mai

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 21, 7:06 pm, greg <[EMAIL PROTECTED]> wrote: > Aaron Brady wrote: > > Tell me, what happens during a call to the following C++ function? > > > void f( std::vector< int > x ); > > The same thing as would happen if you wrote > >    std::vector x = actual_parameter_expression; > > > what happen

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: You've just *assumed* that assignment in Algol 60 doesn't involving copying. I've done no such thing. I've *refrained* from assuming that the "assignment" in the definition always has to refer to Algol 60 assignment. You're the one insisting on tying everything to Algol.

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Aaron Brady wrote: Tell me, what happens during a call to the following C++ function? void f( std::vector< int > x ); The same thing as would happen if you wrote std::vector x = actual_parameter_expression; what happens during a call to the following Python function? def f( x ): ... T

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Aaron Brady wrote: But wait, is that true assignment? It's assignment, but it's not really copying an object. No new objects are being created -- rather, some of the items within the lhs object are being rebound to already-existing objects. It would be possible for the lhs object's __setitem_

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 21, 4:33 am, Duncan Booth <[EMAIL PROTECTED]> wrote: > Aaron Brady <[EMAIL PROTECTED]> wrote: > >> a[:] = [1, 2, 3] > > > No, that's not assignment, it's syntactic sugar for a __setslice__ > > call.  No copies here. > > Oh dear, perhaps you had better get the Python developers to update the

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Aaron Brady <[EMAIL PROTECTED]> wrote: >> a[:] = [1, 2, 3] > > No, that's not assignment, it's syntactic sugar for a __setslice__ > call. No copies here. > Oh dear, perhaps you had better get the Python developers to update the grammar that Python uses as that seems to think it's an assignment

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 21, 3:11 am, Duncan Booth <[EMAIL PROTECTED]> wrote: > Steven D'Aprano <[EMAIL PROTECTED]> wrote: > > On Fri, 21 Nov 2008 03:32:25 +, Steven D'Aprano wrote: > > >>> Rather it seems to me that the essence of the idea they had in mind > >>> is that call-by-value is equivalent to assignment

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano <[EMAIL PROTECTED]> wrote: > On Fri, 21 Nov 2008 03:32:25 +, Steven D'Aprano wrote: > >>> Rather it seems to me that the essence of the idea they had in mind >>> is that call-by-value is equivalent to assignment. >> >> You've just *assumed* that assignment in Algol 60 doesn't

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Fri, 21 Nov 2008 03:32:25 +, Steven D'Aprano wrote: >> Rather it seems to me that the essence of the idea they had in mind is >> that call-by-value is equivalent to assignment. > > You've just *assumed* that assignment in Algol 60 doesn't involving > copying. Based on the very little I kno

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: On Thu, 20 Nov 2008 14:22:50 +1300, greg wrote: Antoon Pardon wrote: You are changing your argument. In a follow up you made the point that call by value should be as it was intended by the writers of the algol 60 report. No, I was countering the argument that "call by

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Wed, 19 Nov 2008 11:20:05 -0500, Terry Reedy wrote: >> It is useful and convenient to have "null values" like None, but it >> isn't useful to say that None is not a value. > > I never said that. But you've been defending the views of somebody who did. If you're going to play Devil's Advoca

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Thu, 20 Nov 2008 14:22:50 +1300, greg wrote: > Antoon Pardon wrote: > >> You are changing your argument. In a follow up you made the point that >> call by value should be as it was intended by the writers of the algol >> 60 report. > > No, I was countering the argument that "call by value" is

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 19, 7:22 pm, greg <[EMAIL PROTECTED]> wrote: > Antoon Pardon wrote: > > You are changing your argument. In a follow up you > > made the point that call by value should be as it > > was intended by the writers of the algol 60 report. > > No, I was countering the argument that "call by value"

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Antoon Pardon wrote: You are changing your argument. In a follow up you made the point that call by value should be as it was intended by the writers of the algol 60 report. No, I was countering the argument that "call by value" is short for "call by copying the value". I was pointing out that

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] wrote: > On Nov 18, 10:22 am, Steve Holden <[EMAIL PROTECTED]> wrote > in thread "Python-URL! weekly Python news and links (Nov 17)": >> [EMAIL PROTECTED] wrote: >> [...] >>> One of the reasons I would like to formulate a good >>> model of an object's value and type is so that I c

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: On Tue, 18 Nov 2008 15:55:10 -0500, Terry Reedy wrote: To me, that distortion of his (and my) point is silly. 0 partipipates in numerous integer operations, whereas None participates in no NoneType operations. (Neither has attributes.) And that is the difference he is

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On 2008-11-19, greg <[EMAIL PROTECTED]> wrote: > Antoon Pardon wrote: >> Call by value is officially defined in terms of assignment in >> a context where assignments means copying and in a definition >> of a specifix language. >> >> You can't lift this part out of the definition of algol 60 >> and

Re: Official definition of call-by-value (Re: Finding the instance reference...)

En Wed, 19 Nov 2008 01:14:28 -0200, <[EMAIL PROTECTED]> escribió: On Nov 18, 10:22 am, Steve Holden <[EMAIL PROTECTED]> wrote in thread "Python-URL! weekly Python news and links (Nov 17)": [EMAIL PROTECTED] wrote: [...] One of the reasons I would like to formulate a good model of an object's va

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Tue, 18 Nov 2008 15:55:10 -0500, Terry Reedy wrote: > Steven D'Aprano wrote: >> On Sun, 16 Nov 2008 15:46:54 -0800, rurpy wrote: > >> For example, consider the two electrons around a helium nucleus. They >> have the same mass, the same speed, the same spin, the same electric >> charge, the sam

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 18, 10:22 am, Steve Holden <[EMAIL PROTECTED]> wrote in thread "Python-URL! weekly Python news and links (Nov 17)": > [EMAIL PROTECTED] wrote: > [...] >> One of the reasons I would like to formulate a good >> model of an object's value and type is so that I could >> try to offer something be

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Antoon Pardon wrote: Call by value is officially defined in terms of assignment in a context where assignments means copying and in a definition of a specifix language. You can't lift this part out of the definition of algol 60 and say it applies equally well in languages with different assignme

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 18, 2:55 pm, Terry Reedy <[EMAIL PROTECTED]> wrote: > Steven D'Aprano wrote: > > On Sun, 16 Nov 2008 15:46:54 -0800, rurpy wrote: > > For example, consider the two electrons around a helium nucleus. They > > have the same mass, the same speed, the same spin, the same electric > > charge, the

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Terry Reedy wrote: Steven D'Aprano wrote: On Sun, 16 Nov 2008 15:46:54 -0800, rurpy wrote: For example, consider the two electrons around a helium nucleus. They have the same mass, the same speed, the same spin, the same electric charge, the same magnetic moment, they even have the same loca

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: On Sun, 16 Nov 2008 15:46:54 -0800, rurpy wrote: For example, consider the two electrons around a helium nucleus. They have the same mass, the same speed, the same spin, the same electric charge, the same magnetic moment, they even have the same location in space (tech

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 17, 7:35 pm, Craig Allen <[EMAIL PROTECTED]> wrote: >> >> * Do all objects have values? (Ignore the Python >> >> docs if necessary.) >> >> > If one allows null values, I am current thinking yes. >> >> I don't see a difference between a "null value" >> and not having a value. > > I think the

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: > On Mon, 17 Nov 2008 18:35:04 -0800, Craig Allen wrote: > > * Do all objects have values? (Ignore the Python > docs if necessary.) If one allows null values, I am current thinking yes. >>> I don't see a difference between a "null value" and not having a value.

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On 2008-11-12, greg <[EMAIL PROTECTED]> wrote: > Steven D'Aprano wrote: > >> Why should anyone take the "Revised Report on the Algorithmic Language >> Algol 60" as the "official" (only?) definition of call-by-value for all >> languages everywhere? > > Since the term was more or less invented by t

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, 16 Nov 2008 15:46:54 -0800, rurpy wrote: > Since many responses to my definition of value raised similar points, I > will try and respond generally here. > > In hindsight, I should not have used the word "value"; it is far too > overloaded with preexisting semantics for me to have attempt

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 18, 2:21 am, Antoon Pardon <[EMAIL PROTECTED]> wrote: > On 2008-11-12, greg <[EMAIL PROTECTED]> wrote: > > > Here is the definition of call-by-value from the > > "Revised Report on the Algorithmic Language Algol 60" > >: > > > 4.7.3.1. Value assignm

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On 2008-11-12, greg <[EMAIL PROTECTED]> wrote: > Here is the definition of call-by-value from the > "Revised Report on the Algorithmic Language Algol 60" >: > > 4.7.3.1. Value assignment (call by value). All formal parameters quoted in > the > value part

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Mon, 17 Nov 2008 18:35:04 -0800, Craig Allen wrote: >> >> * Do all objects have values? (Ignore the Python >> >> docs if necessary.) >> >> > If one allows null values, I am current thinking yes. >> >> I don't see a difference between a "null value" and not having a value. >> >> > I think the d

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, 16 Nov 2008 23:34:58 -0500, Terry Reedy wrote: > Steven D'Aprano wrote: > class EqualsAll(object): >> ... def __eq__(self, other): >> ... return True >> ... > 5 == EqualsAll() >> True >> >> >> The methods of 5 don't even get called. > > Why do you say that? As

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 17, 8:35 pm, Craig Allen <[EMAIL PROTECTED]> wrote: > > >> * Do all objects have values? (Ignore the Python > > >>  docs if necessary.) > > > > If one allows null values, I am current thinking yes. > > > I don't see a difference between a "null value" > > and not having a value. > > I think

Re: Official definition of call-by-value (Re: Finding the instance reference...)

> >> * Do all objects have values? (Ignore the Python > >> docs if necessary.) > > > If one allows null values, I am current thinking yes. > > I don't see a difference between a "null value" > and not having a value. > I think the difference is concrete... an uninitialized variable in C has no va

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] wrote: Or one could adopt what Terry Reedy called a 4-aspect view: an object is identity, class, value (or local-state or something) and intrinsic-value. What I specifically said is id, class, instance attributes, and private data. So objects have only one, some only the ot

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 16, 5:12 pm, Steve Holden <[EMAIL PROTECTED]> wrote: >> The Python Reference Manual states that an object >> consists of identity, type, and value. "Identity" >> seems to be non-controversial. >> >> Let's take "type" as meaning the attributes an >> object inherits from it's class. "value"

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: Because of Python's interpreted nature, names can't be compiled away as in C, they need a concrete runtime existence, but does the language definition need to assume that? Of course. It wouldn't be Python if they didn't. However, remember that objects don't have names.

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] wrote: > Since many responses to my definition of > value raised similar points, I will try > and respond generally here. > > In hindsight, I should not have used the > word "value"; it is far too overloaded with > preexisting semantics for me to have attempted > to redefine it,

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Since many responses to my definition of value raised similar points, I will try and respond generally here. In hindsight, I should not have used the word "value"; it is far too overloaded with preexisting semantics for me to have attempted to redefine it, even if it is the word used (but not def

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: > On Sat, 15 Nov 2008 11:17:07 -0800, rurpy wrote: [...] >> * How can I find an object's value (if I don't believe >> .str(), .repr(), etc)? Use gdb. :-) > > I would say the object's value is the value, so if you have the object, > you have its value. > [...] There's a

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: > On Sat, 15 Nov 2008 19:42:33 -0800, rurpy wrote: [...] >> But I propose that one can define value in a precise way that >> captures what most people think of as value, and avoids confusing >> objects (or references to them) and the value of objects. > > Good luck. I think

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, 16 Nov 2008 04:12:53 -0500, Derek Martin wrote: > On Sun, Nov 16, 2008 at 06:06:20AM +, Steven D'Aprano wrote: >> >>> * Do all objects have values? (Ignore the Python >> >>> docs if necessary.) >> >> >> >> If one allows null values, I am current thinking yes. >> > >> > I don't see a

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sat, 15 Nov 2008 19:42:33 -0800, rurpy wrote: > You are saying there is no objective definition of "value". I disagree. > I think one can define value in a useful way that is precise, > objective, and useful. No, I'm not saying that there is no objective definition of value. I'm saying that

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Derek Martin <[EMAIL PROTECTED]> writes: > I think he meant None... Or at least, I personally see a distinction > between zero and None (and so do the Python docs). Zero is a value, > whereas None is specifically intended to denote the lack of any value. None is an 'value' which is intended to

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, Nov 16, 2008 at 09:30:45AM +, Arnaud Delobelle wrote: > [...] > > If you like, you could think of the value of an object as the set of > > all possible values to which the object may evaluate in every possible > > context, given a particular state of the object. > > This definition loo

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Derek Martin <[EMAIL PROTECTED]> writes: > On Thu, Nov 13, 2008 at 11:58:18AM -0800, [EMAIL PROTECTED] wrote: >> I have yet to see any reasonable definition of a Python value in the >> Python docs or elsewhere, despite the fact that a value is one of >> the three defining characteristics of an obj

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, Nov 16, 2008 at 08:38:25AM +, Steven D'Aprano wrote: > I believe that the language reference says that objects have an identity, > a type and state, but I'm too lazy too look it up. I'd be happy with that > definition. They do indeed say value, not state. As I said in a different me

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sun, Nov 16, 2008 at 06:06:20AM +, Steven D'Aprano wrote: > >>> * Do all objects have values? (Ignore the Python > >>> docs if necessary.) > >> > >> If one allows null values, I am current thinking yes. > > > > I don't see a difference between a "null value" and not having a value. > [...

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sat, 15 Nov 2008 19:41:20 -0800, rurpy wrote: >> I prefer another definition of object: an object *is* a value, rather >> than *has* a value. That value consists of identity, type (or class), >> and everything else of interest which is sometimes also called "value". >> Since identity is usually

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Thu, Nov 13, 2008 at 11:58:18AM -0800, [EMAIL PROTECTED] wrote: > I have yet to see any reasonable definition of a Python value in the > Python docs or elsewhere, despite the fact that a value is one of > the three defining characteristics of an object, a central concept > in Python. Why does i

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Sat, 15 Nov 2008 11:17:07 -0800, rurpy wrote: >>> * Can I create an object that has a value that >>> is the same as int(3) without somehow using an int(3) object in its >>> construction? [...] >> Yes: mpz(3) where mpz is multi-precision int class with same set of >> possible values as Python

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[Tried multiple times to post this but Google errors out so will try posting in two parts... this is part 2] On Nov 14, 11:51 pm, Steven D'Aprano <[EMAIL PROTECTED] cybersource.com.au> wrote: > On Fri, 14 Nov 2008 22:56:52 -0500, Terry Reedy wrote: >> [EMAIL PROTECTED] wrote: >>> On Nov 13, 4:53 pm

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[Tried multiple times to post this but Google errors out so will try posting in two parts... this is part 1] On Nov 14, 11:51 pm, Steven D'Aprano <[EMAIL PROTECTED] cybersource.com.au> wrote: > On Fri, 14 Nov 2008 22:56:52 -0500, Terry Reedy wrote: > >> [EMAIL PROTECTED] wrote: >>> On Nov 13, 4:53

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 15, 4:12 pm, Terry Reedy <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote: >> On Nov 14, 8:56 pm, Terry Reedy <[EMAIL PROTECTED]> wrote: ...snip... * Does an object's behavior (methods) affect its value? >>> My first answer is No. Instance methods are attributes of a class an

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] wrote: On Nov 14, 8:56 pm, Terry Reedy <[EMAIL PROTECTED]> wrote: First of all, thanks. Thanks to your answers I have finally been able to formulate a concept of Python values. Now we'll see if it is valid/usable... :-) Good questions help refine a concept. * Can I create

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 14, 8:56 pm, Terry Reedy <[EMAIL PROTECTED]> wrote: > [EMAIL PROTECTED] wrote: >> On Nov 13, 4:53 pm, Terry Reedy wrote: >>> [EMAIL PROTECTED] wrote: >>> I have yet to see any reasonable definition of a Python value in the Python docs or elsewhere, despite the fact that a valu

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] writes: > I have yet to see any reasonable definition of a Python > value in the Python docs or elsewhere, despite the fact > that a value is one of the three defining characteristics > of an object, a central concept in Python. I don't remember how the expression 'object value'

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 15, 12:51 am, Steven D'Aprano <[EMAIL PROTECTED] cybersource.com.au> wrote: > On Fri, 14 Nov 2008 22:56:52 -0500, Terry Reedy wrote: snip > I would say that the answer to this is, "Would you like to include > behaviour in value?". Let me give you an example: > > class String(string): >     d

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Fri, 14 Nov 2008 22:56:52 -0500, Terry Reedy wrote: > [EMAIL PROTECTED] wrote: >> On Nov 13, 4:53 pm, Terry Reedy wrote: >>> [EMAIL PROTECTED] wrote: >>> I have yet to see any reasonable definition of a Python value in the Python docs or elsewhere, despite the fact that a value is one

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] wrote: On Nov 13, 4:53 pm, Terry Reedy wrote: [EMAIL PROTECTED] wrote: I have yet to see any reasonable definition of a Python value in the Python docs or elsewhere, despite the fact that a value is one of the three defining characteristics of an object, a central concept in

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 13, 4:53 pm, Terry Reedy wrote: > [EMAIL PROTECTED] wrote: > >> I have yet to see any reasonable definition of a Python >> value in the Python docs or elsewhere, despite the fact >> that a value is one of the three defining characteristics >> of an object, a central concept in Python. > > I

Re: Official definition of call-by-value (Re: Finding the instance reference...)

[EMAIL PROTECTED] wrote: I have yet to see any reasonable definition of a Python value in the Python docs or elsewhere, despite the fact that a value is one of the three defining characteristics of an object, a central concept in Python. I noticed too. My try: The value of an object is the i

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 12, 7:09 pm, George Sakkis <[EMAIL PROTECTED]> wrote: > On Nov 12, 4:05 pm, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > >> greg wrote: >> >> It's not only misleading, it's also a seriously flawed reading of the >> >> original text - the Algol 60 report explicitly talks about assignment >> >>

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Fredrik Lundh wrote: greg wrote: If you're going to indulge in argument by authority, you need to pick authorities that can be considered, er, authoritative in the field concerned... Like Barbara Liskov, who's won tons of awards for her work on computer science and programming languages, and

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On 2008-11-13, greg <[EMAIL PROTECTED]> wrote: > Grant Edwards wrote: > >> I stopped paying much attention to this thread a while ago, but >> you've got to admire the persistence of somebody who soldiers >> on even though Aahz, Fredrik Lund, and Steve Holden are all on >> the other side of the argu

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 12, 2:05 pm, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > Python's definition of the word "value" can be found in the language > reference: > > http://docs.python.org/reference/datamodel.html#objects-values-and-types > > Using that definition, a Python expression yields an object, not an > obj

Re: Official definition of call-by-value (Re: Finding the instance reference...)

greg wrote: If you're going to indulge in argument by authority, you need to pick authorities that can be considered, er, authoritative in the field concerned... Like Barbara Liskov, who's won tons of awards for her work on computer science and programming languages, and who was among the fir

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Fredrik Lundh wrote: Python's definition of the word "value" can be found in the language reference: http://docs.python.org/reference/datamodel.html#objects-values-and-types That whole passage is talking almost exclusively about the value of an *object*: Every object has an identity, a ty

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 13, 3:44 am, greg <[EMAIL PROTECTED]> wrote: > Grant Edwards wrote: > > I stopped paying much attention to this thread a while ago, but > > you've got to admire the persistence of somebody who soldiers > > on even though Aahz, Fredrik Lund, and Steve Holden are all on > > the other side of t

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Grant Edwards wrote: I stopped paying much attention to this thread a while ago, but you've got to admire the persistence of somebody who soldiers on even though Aahz, Fredrik Lund, and Steve Holden are all on the other side of the argument... Those people clearly know a great deal about Pytho

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steve Holden wrote: greg wrote: Do you agree that it makes sense to talk about assigning that value to something? No. Why do you think that we are (mostly) careful to talk about binding names and values instead? That's an odd position to take, considering that the Python docs use the word "

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Nov 12, 4:05 pm, Fredrik Lundh <[EMAIL PROTECTED]> wrote: > greg wrote: > >> It's not only misleading, it's also a seriously flawed reading of the > >> original text - the Algol 60 report explicitly talks about assignment > >> of *values*. > > > Do you agree that an expression in Python has a v

Re: Official definition of call-by-value (Re: Finding the instance reference...)

In article <[EMAIL PROTECTED]>, Grant Edwards <[EMAIL PROTECTED]> wrote: >On 2008-11-12, Steve Holden <[EMAIL PROTECTED]> wrote: >> greg wrote: > >I stopped paying much attention to this thread a while ago, but >you've got to admire the persistence of somebody who soldiers >on even though Aahz, Fr

Re: Official definition of call-by-value (Re: Finding the instance reference...)

greg wrote: It's not only misleading, it's also a seriously flawed reading of the original text - the Algol 60 report explicitly talks about assignment of *values*. Do you agree that an expression in Python has a value? > Do you agree that it makes sense to talk about assigning that value t

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On 2008-11-12, Steve Holden <[EMAIL PROTECTED]> wrote: > greg wrote: I stopped paying much attention to this thread a while ago, but you've got to admire the persistence of somebody who soldiers on even though Aahz, Fredrik Lund, and Steve Holden are all on the other side of the argument... -- G

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Wed, Nov 12, 2008 at 2:01 PM, Steve Holden <[EMAIL PROTECTED]> wrote: > Now, can we get on to something substantive like how many angels can > dance on the head of a pin? > Oh, come on, that's too easy! 42. I thought that by now everybody knew that. Francesco -- http://mail.python.org/mailman/

Re: Official definition of call-by-value (Re: Finding the instance reference...)

greg wrote: > Fredrik Lundh wrote: > >> It's not only misleading, it's also a seriously flawed reading of the >> original text - the Algol 60 report explicitly talks about assignment >> of *values*. > > Do you agree that an expression in Python has a value? > Most expressions have values. The on

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Fredrik Lundh wrote: It's not only misleading, it's also a seriously flawed reading of the original text - the Algol 60 report explicitly talks about assignment of *values*. Do you agree that an expression in Python has a value? Do you agree that it makes sense to talk about assigning that v

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: If you insist that Python is call by value, the only way that can work is by defining values to be references, which is nothing like Algol. No, that's not the only way. You can also make it work by accepting the original definition of call-by-value at face value -- i.e.

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano wrote: Why should anyone take the "Revised Report on the Algorithmic Language Algol 60" as the "official" (only?) definition of call-by-value for all languages everywhere? Since the term was more or less invented by the people who designed Algol, I thought it would be a good i

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Aahz wrote: There you have it -- call by value is offially defined in terms of assignment. There is no mention in there of copying. So it's perfectly correct to use it in relation to Python. Except, of course, for the fact that it is generally misleading. It's not only misleading, it's also

Re: Official definition of call-by-value (Re: Finding the instance reference...)

Steven D'Aprano <[EMAIL PROTECTED]> writes: > I am very happy to say that x=1 implies that the value of x is the object > 1 itself, in fact I would insist on such a definition of value. > > If you insist that Python is call by value, the only way that can work is > by defining values to be refer

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Wed, 12 Nov 2008 02:44:42 +, Steven D'Aprano wrote: > But one thing is clear: values aren't references. Given the assignment > x=1, the value of x is not "a reference to 1" but 1 itself. So the one > thing we can unambiguously say is that Algol's assignment model is not > the same as Python

Re: Official definition of call-by-value (Re: Finding the instance reference...)

On Wed, 12 Nov 2008 13:10:10 +1300, greg wrote: > Here is the definition of call-by-value from the "Revised Report on the > Algorithmic Language Algol 60" > : Why should anyone take the "Revised Report on the Algorithmic Language Algol 60" as the "offi

Re: Official definition of call-by-value (Re: Finding the instance reference...)

In article <[EMAIL PROTECTED]>, greg <[EMAIL PROTECTED]> wrote: > >Here is the definition of call-by-value from the >"Revised Report on the Algorithmic Language Algol 60" >: > >4.7.3.1. Value assignment (call by value). All formal parameters quoted in the

Official definition of call-by-value (Re: Finding the instance reference...)

Here is the definition of call-by-value from the "Revised Report on the Algorithmic Language Algol 60" : 4.7.3.1. Value assignment (call by value). All formal parameters quoted in the value part of the procedure declaration heading are assigned the valu