October 2016 - Pharo-users - lists.pharo.org

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by CodeDmitry

I tried so hard to find an example of Ruby using smalltalk message syntax. You can do something like: class Dictionary attr_accessor :dict def initialize() @dict = {} end def at(*args) if (args.length == 1) then return @dict[args[0]] end @dict[args[0]] = args[1][:put] end end dict = Dictionary.new dict.at 3, put: 4 puts dict.dict puts dict.at 3 But it's pretty expensive to disambiguate messages to "at" this way. The JS approach was much simpler since each message like 'at:put:' or 'at' were sent to appropriate receiver functions, whereas this is just a spaghetti :\ I'm sure there's more elegant way of doing this in Ruby but I haven't found it :| -- View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by Dimitris Chloupis

"I was actually curious about this in Ruby as well, since Ruby also doesn't have the Smalltalk message syntax. " Actually, it does when i said in my reply "The only other languages that have such an implementation are ObjC and Ruby which borrow this directly from Smalltalk." What I mean is that both ObjC and Ruby has a message based OOP system , like Smalltalk. http://rubylearning.com/blog/2010/11/03/do-you-understand-rubys-objects-mes… On Sun, Oct 16, 2016 at 11:50 AM CodeDmitry <dimamakhnin(a)gmail.com> wrote: > I was actually curious about this in Ruby as well, since Ruby also doesn't > have the Smalltalk message syntax. > > I figure that the magic behind it is that Smalltalk takes strings like > "dict > at: 'foo' put: 'bar'" and evaluates them into a JavaScript equivalent of > "dict['at:put:']('foo', 'bar')". > > Basically, my proof of concept(I cheated with regex to cut time): > > 'use strict'; > > var Dictionary = function Dictionary() { > this.dict = {}; > }; > Dictionary.prototype['at:put:'] = function(index, value) { > this.dict[index] = value; > }; > Object.defineProperty(Dictionary, 'new', { > get: function () { > return new this; > } > }); > > function st_eval(str) { > var x = str.match(/(dict)\s+(at):\s+'(foo)'\s+(put):\s+'(bar)'/); > var target = x[1]; > var callName = x[2] + ':' + x[4] + ':'; > var argv = [x[3], x[5]]; > var realTarget = eval(target); > realTarget[callName].apply(realTarget, argv); > } > > var dict = Dictionary.new; > console.log(dict); > //dict['at:put:']('foo', 'bar'); > console.log(dict); > st_eval("dict at: 'foo' put: 'bar'"); > console.log(dict); > > > > > > -- > View this message in context: > http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by CodeDmitry

I was actually curious about this in Ruby as well, since Ruby also doesn't have the Smalltalk message syntax. I figure that the magic behind it is that Smalltalk takes strings like "dict at: 'foo' put: 'bar'" and evaluates them into a JavaScript equivalent of "dict['at:put:']('foo', 'bar')". Basically, my proof of concept(I cheated with regex to cut time): 'use strict'; var Dictionary = function Dictionary() { this.dict = {}; }; Dictionary.prototype['at:put:'] = function(index, value) { this.dict[index] = value; }; Object.defineProperty(Dictionary, 'new', { get: function () { return new this; } }); function st_eval(str) { var x = str.match(/(dict)\s+(at):\s+'(foo)'\s+(put):\s+'(bar)'/); var target = x[1]; var callName = x[2] + ':' + x[4] + ':'; var argv = [x[3], x[5]]; var realTarget = eval(target); realTarget[callName].apply(realTarget, argv); } var dict = Dictionary.new; console.log(dict); //dict['at:put:']('foo', 'bar'); console.log(dict); st_eval("dict at: 'foo' put: 'bar'"); console.log(dict); -- View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by Dimitris Chloupis

`There is no equivalent in JavaScript because Javascript does not have function calls with keyword arguments and even if it , it would still be not equivalent at least technically. The message "at:put:" is indeed a keyword that is part of the dictionary of the object and not just a generic dictionary. So each object has its own dictionary that associates keywords to method calls. So in Smalltalk you can not access neither variables (class or instance) nor methods (class or instance) outside the object, they all are accessed through messages. This happens to hide the implementation, hence the complexity of the object. The user does not need to know how the Object works only how to use it. The only other languages that have such an implementation are ObjC and Ruby which borrow this directly from Smalltalk. Also Javascript uses prototype based OOP while Snalltalk is the first language to implement class based OOP. They are similar but not the same. On Sun, Oct 16, 2016 at 8:28 AM CodeDmitry <dimamakhnin(a)gmail.com> wrote: > So "at: x put: y" translates to a method named #at:put:(or "at:put:")? > > |dict| > dict := Dictionary new. > dict at: 'foo' put: 'bar'. > > So javascript equivalent would be(assuming the Dictionary object existed). > > var dict; > > dict = new Dictionary; > dict['at:put:']('foo', 'bar'); > > > > -- > View this message in context: > http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by Tudor Girba

The value of the method name is at:put: # denotes a Symbol, which is a subclass of String. The difference between the two is that two symbols with the same value will actually be the same object, while this is not necessarily the case with strings: stringA := String newFrom: 'string'. stringB := String newFrom: 'string'. stringA == stringB âfalse". symbolA := Symbol newFrom: 'symbol'. symbolB := Symbol newFrom: 'symbol'. symbolA == symbolB "true" Cheers, Doru > On Oct 16, 2016, at 7:19 AM, CodeDmitry <dimamakhnin(a)gmail.com> wrote: > > So "at: x put: y" translates to a method named #at:put:(or "at:put:")? > > |dict| > dict := Dictionary new. > dict at: 'foo' put: 'bar'. > > So javascript equivalent would be(assuming the Dictionary object existed). > > var dict; > > dict = new Dictionary; > dict['at:put:']('foo', 'bar'); > > > > -- > View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > -- www.tudorgirba.com www.feenk.com "The coherence of a trip is given by the clearness of the goal."

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by CodeDmitry

So "at: x put: y" translates to a method named #at:put:(or "at:put:")? |dict| dict := Dictionary new. dict at: 'foo' put: 'bar'. So javascript equivalent would be(assuming the Dictionary object existed). var dict; dict = new Dictionary; dict['at:put:']('foo', 'bar'); -- View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by Tudor Girba

Hi, : is part of the method name. So, the method: Dictionary>>at: key put: anObject has the name #'at:put:' and the object defining this method will understand a message #âat:put:â. To better understand this, you can play with inspecting the method objects, like below: Does this answer the question? Cheers, Doru > On Oct 16, 2016, at 6:44 AM, CodeDmitry <dimamakhnin(a)gmail.com> wrote: > > I understand that it is a single message send, but to know how to handle the > message at runtime, the parser needs to somehow determine where the > implementation of that message is. It must do a lookup based on multiple > keys(at, and put), which is really confusing. "methods" are easy to look up > because they only have one name, but messages have one name which is split > amongst each argument. > > Simple concatenation does not make sense, since {at: x, put: y} and {a: x, > tput: y} are different messages. > > The only way I can think of this being implemented "easily" is by storing a > table of entries {num_args, arg_names, impl_ref}, and then have the function > "send" do a linear search over this table until it finds an entry with > num_args = 2, each arg_name matching the argument name keys in order, and > then calling the impl_ref with the array of values without the names. > > I'm wondering if there is a way to do this without having to loop over every > single message the object has, then every message its' parent object has, > and so on, just to find which function you actually want to call. > > > > > > -- > View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > -- www.tudorgirba.com www.feenk.com "We can create beautiful models in a vacuum. But, to get them effective we have to deal with the inconvenience of reality."

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by Charlie Robbats

I think the nub of your confusion is twofold. The method #at:put: is a keyword method and it isn't right to think o them as two keys. It is one compound key and unlike most every other system, Smalltalk keyword message sends allow the programmer to name each argument. This is very fine indeed. The other item is in your thinking that these methods are defined in a prototype chain, like JavaScript. Primarily Smalltalk is a class-based inheritance system for method lookup on message send. What I mean by your example is that when the message #at:put: is sent, the system will start with the concrete class in question, Array, and attempts lookup of #at:put:. When this fails, it then traverses the lookup to the superclass (->ArrayedCollection) and so on on lookup failure (->SequenceableCollection ->Collection ->Object) and at the Object class, the lookup into that Class's methodDictionary succeeds. It tuns out that Object>>#at:put: is a primitive in the vm (#61) that is able to store into an Array object, a variable class and indexable, by the way. Consider the method Array>>atWrap:put: also calling primitive 61. This may help with foundations: http://samizdat.cc/shelf/documents/2004/08.02-historyOfSmalltalk/historyOfS… I hope this helps. On 10/16/2016 12:44 AM, CodeDmitry wrote: > I understand that it is a single message send, but to know how to handle the > message at runtime, the parser needs to somehow determine where the > implementation of that message is. It must do a lookup based on multiple > keys(at, and put), which is really confusing. "methods" are easy to look up > because they only have one name, but messages have one name which is split > amongst each argument. > > Simple concatenation does not make sense, since {at: x, put: y} and {a: x, > tput: y} are different messages. > > The only way I can think of this being implemented "easily" is by storing a > table of entries {num_args, arg_names, impl_ref}, and then have the function > "send" do a linear search over this table until it finds an entry with > num_args = 2, each arg_name matching the argument name keys in order, and > then calling the impl_ref with the array of values without the names. > > I'm wondering if there is a way to do this without having to loop over every > single message the object has, then every message its' parent object has, > and so on, just to find which function you actually want to call. > > > > > > -- > View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. >

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by CodeDmitry

I understand that it is a single message send, but to know how to handle the message at runtime, the parser needs to somehow determine where the implementation of that message is. It must do a lookup based on multiple keys(at, and put), which is really confusing. "methods" are easy to look up because they only have one name, but messages have one name which is split amongst each argument. Simple concatenation does not make sense, since {at: x, put: y} and {a: x, tput: y} are different messages. The only way I can think of this being implemented "easily" is by storing a table of entries {num_args, arg_names, impl_ref}, and then have the function "send" do a linear search over this table until it finds an entry with num_args = 2, each arg_name matching the argument name keys in order, and then calling the impl_ref with the array of values without the names. I'm wondering if there is a way to do this without having to loop over every single message the object has, then every message its' parent object has, and so on, just to find which function you actually want to call. -- View this message in context: http://forum.world.st/How-do-Smalltalk-disambiguate-messages-tp4918946p4918… Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com.

Oct. 16, 2016

Re: [Pharo-users] How do Smalltalk disambiguate messages?

by Gabriel Cotelli

The message is "at:put:". It's a single message send. I encourage you to try the ProfStef tutorial to understand the basis. On Oct 16, 2016 01:17, "CodeDmitry" <dimamakhnin(a)gmail.com> wrote: > I am trying to do a JavaScript experiment to make Objects behave like > Smalltalk objects. > > example: > > "reminder: Smalltalk arrays start at 1." > |arr| > a := Array new: 1. > a at: 1 put: 'Hello, World'. > > Here, the Smalltalk array has a message "at: index put: value" which is > defined many layers of prototype chaining down, at Object in category > accessing. > > However there are many messages on the way traversing the prototype chain > that start with "at:", such as(SequenceableCollection) "at: x ifAbsent: y", > "at: x incrementBy: y". > > How does Smalltalk tell which message is which? Does it merge the messages > into a single message such as "at: x put: y" to "atPut(x, y)" at some > point? > > Without knowing this, I have to traverse the whole call chain and check > whether each argument is called in a specific way, which is incredibly > expensive. If there was a single name such as "atPut" I can easily just do > a > dictionary lookup for this name and get it at O(1). > > Does Smalltalk actually store each message? > > > > -- > View this message in context: http://forum.world.st/How-do- > Smalltalk-disambiguate-messages-tp4918946.html > Sent from the Pharo Smalltalk Users mailing list archive at Nabble.com. > >

Oct. 16, 2016