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How are arguments a legit argument to Array.slice?

 
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lorlarz
PostPosted: Thu Aug 28, 2008 8:36 pm    Post subject: How are arguments a legit argument to Array.slice?
       
In the code sample below, how are arguments a legitimate
argument to Array.slice?


Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments), object =
args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();
 

 
Richard Cornford
PostPosted: Thu Aug 28, 2008 9:16 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
lorlarz wrote
Quote:
In the code sample below, how are arguments a legitimate
argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();

Code that is intended to be read by humans (so anything posted to Usenet
with the intention of its being examined by other participants in a
group) should be indented (using spaces in posts not tabs as tabs don't
receive uniform (or necessarily useful) handling in newsreader
software).

In the code above - arguments - is never an argument to Array.slice. All
occurrences of - arguments - as an argument are as an argument to -
Function.prototype.call -.

Richard.
 

 
RobG
PostPosted: Fri Aug 29, 2008 1:22 am    Post subject: Re: How are arguments a legit argument to Array.slice?
       
On Aug 29, 6:36 am, lorlarz <lorl...@gmail.com> wrote:
Quote:
In the code sample below, how are arguments a legitimate
 argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments), object > args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));};

Seems to me that:

return fn.apply(object, args);

is sufficient.


--
Rob
 

 
Richard Cornford
PostPosted: Fri Aug 29, 2008 12:34 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
lorlarz wrote:
Quote:
On Aug 28, 6:16 pm, Richard Cornford wrote:
lorlarz wrote
snip
In the code sample below, how are arguments a legitimate
argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();

Code that is intended to be read by humans ...
should be indented ...
snip
In the code above - arguments - is never an argument to
Array.slice. All occurrences of - arguments - as an argument
are as an argument to - Function.prototype.call -.

Richard.- Hide quoted text -
^^^^^^^^^^^^^^^^^^^^
- Show quoted text -
^^^^^^^^^^^^^^^^^^^^^


I did _not_ write that final text. Why are you attributing words to me
that I did not write? That represents a serious breach of netiquette,
and is disingenuous at the very least.

Quote:
This code is from a draft of a new JavaScript book

And the code is indented in that presentation (that is not a question,
and I don't need to see it in order to *know* that it *is* indented).

Quote:
by a major expert.

YMMV

Quote:
He is grabbing

What it the technical meaning of "grabbing" in javascript?

Quote:
the arguments property of the function and passing
it as an argument to Array.prototype.slice

No he is not. That is not what the code above does, as I have already
told you once; at no point in the code above does an - arguments -
object get used as an argument to the - slice - method.

Quote:
The contents of the arguments property that the function
receives is just the object myObject, so there seems to be
nothing to slice.

The - slice - method is used in order to transfer the values of the
'array index' properties of an - arguments - object to corresponding
properties of a newly created Array object. This allows - shift - to be
called on that Array in order to extract its first element (the
reference to the - myObject - object) and leave any other values for
later use in any call to the - fn - function.

Quote:
I may have to ask the author himself;

You still may have to work out what the correct question is.

Quote:
perhaps this is a code error in the draft.

No, the code is fine; a straight reproduction of a run-of-the-mill -
bind - implementation. Obviously the accompanying text is not very
effective as an explanation of what it going on here, but that is 'major
experts' for you.

Richard.
 

 
lorlarz
PostPosted: Fri Aug 29, 2008 1:02 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
On Aug 28, 6:16 pm, "Richard Cornford" <Rich...@litotes.demon.co.uk>
wrote:
Quote:
lorlarz wrote





In the code sample below, how are arguments a legitimate
argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();

Code that is intended to be read by humans (so anything posted to Usenet
with the intention of its being examined by other participants in a
group) should be indented (using spaces in posts not tabs as tabs don't
receive uniform (or necessarily useful) handling in newsreader
software).

In the code above - arguments - is never an argument to Array.slice. All
occurrences of - arguments - as an argument are as an argument to -
Function.prototype.call -.

Richard.- Hide quoted text -

- Show quoted text -

This code is from a draft of a new JavaScript book
by a major expert. He is grabbing
the arguments property of the function and passing
it as an argument to Array.prototype.slice

The contents of the arguments property that the function
receives is just the object myObject, so there seems to be
nothing to slice.

I may have to ask the author himself; perhaps this
is a code error in the draft.
 

 
lorlarz
PostPosted: Fri Aug 29, 2008 1:03 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
On Aug 28, 8:22 pm, RobG <rg...@iinet.net.au> wrote:
Quote:
On Aug 29, 6:36 am, lorlarz <lorl...@gmail.com> wrote:

In the code sample below, how are arguments a legitimate
 argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments), object > > args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));};

Seems to me that:

  return fn.apply(object, args);

is sufficient.

--
Rob

Yes, what you say at least makes sense to me.
 

 
lorlarz
PostPosted: Fri Aug 29, 2008 3:25 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
On Aug 29, 9:34 am, "Richard Cornford" <Rich...@litotes.demon.co.uk>
wrote:
Quote:
lorlarz wrote:
On Aug 28, 6:16 pm, Richard Cornford wrote:
lorlarz wrote
snip
In the code sample below, how are arguments a legitimate
argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();

Code that is intended to be read by humans ...
should be indented ...
snip
In the code above - arguments - is never an argument to
Array.slice. All occurrences of - arguments - as an argument
are as an argument to - Function.prototype.call -.

Richard.- Hide quoted text -

           ^^^^^^^^^^^^^^^^^^^^>> - Show quoted text -

   ^^^^^^^^^^^^^^^^^^^^^

I did _not_ write that final text. Why are you attributing words to me
that I did not write? That represents a serious breach of netiquette,
and is disingenuous at the very least.

This code is from a draft of a new JavaScript book

And the code is indented in that presentation (that is not a question,
and I don't need to see it in order to *know* that it *is* indented).

by a major expert.

YMMV

He is grabbing

What it the technical meaning of "grabbing" in javascript?

the arguments property of the function and passing
it as an argument to Array.prototype.slice

No he is not. That is not what the code above does, as I have already
told you once; at no point in the code above does an - arguments -
object get used as an argument to the - slice - method.

The contents of the arguments property that the function
receives is just the object myObject, so there seems to be
nothing to slice.

The - slice - method is used in order to transfer the values of the
'array index' properties of an - arguments - object to corresponding
properties of a newly created Array object. This allows - shift - to be
called on that Array in order to extract its first element (the
reference to the - myObject - object) and leave any other values for
later use in any call to the - fn - function.

I may have to ask the author himself;

You still may have to work out what the correct question is.

perhaps this is a code error in the draft.

No, the code is fine; a straight reproduction of a run-of-the-mill -
bind - implementation. Obviously the accompanying text is not very
effective as an explanation of what it going on here, but that is 'major
experts' for you.

Richard.- Hide quoted text -

- Show quoted text -

You were automatically quoted by google and it looks correct to
me. There is just a single ">" in front of your lines and
">>" in front of where you quote me.

In any case, I simple took the google quote and did nothing
but reply below. If there is any validity to your
concern, you will have to take it up with google.

I am trying, but do not yet quite understand your
explanation. Could you spell it out bit by bit
more?

I agree with you that the expert did indeed
fail to explain the code, becuase he provides
no explanation. You may have done a bit better,
but I am still unclear. I think you may be able
to bring me "over the line" if you just detail
a bit more what happens.

(As with my last reply, I used the google
quotinog of your post and did nothing
to alter the way it was quoted.)
 

 
lorlarz
PostPosted: Fri Aug 29, 2008 3:37 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
On Aug 29, 10:25 am, lorlarz <lorl...@gmail.com> wrote:
Quote:
On Aug 29, 9:34 am, "Richard Cornford" <Rich...@litotes.demon.co.uk
wrote:





lorlarz wrote:
On Aug 28, 6:16 pm, Richard Cornford wrote:
lorlarz wrote
snip
In the code sample below, how are arguments a legitimate
argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();

Code that is intended to be read by humans ...
should be indented ...
snip
In the code above - arguments - is never an argument to
Array.slice. All occurrences of - arguments - as an argument
are as an argument to - Function.prototype.call -.

Richard.- Hide quoted text -

           ^^^^^^^^^^^^^^^^^^^^>> - Show quoted text -

   ^^^^^^^^^^^^^^^^^^^^^

I did _not_ write that final text. Why are you attributing words to me
that I did not write? That represents a serious breach of netiquette,
and is disingenuous at the very least.

This code is from a draft of a new JavaScript book

And the code is indented in that presentation (that is not a question,
and I don't need to see it in order to *know* that it *is* indented).

by a major expert.

YMMV

He is grabbing

What it the technical meaning of "grabbing" in javascript?

the arguments property of the function and passing
it as an argument to Array.prototype.slice

No he is not. That is not what the code above does, as I have already
told you once; at no point in the code above does an - arguments -
object get used as an argument to the - slice - method.

The contents of the arguments property that the function
receives is just the object myObject, so there seems to be
nothing to slice.

The - slice - method is used in order to transfer the values of the
'array index' properties of an - arguments - object to corresponding
properties of a newly created Array object. This allows - shift - to be
called on that Array in order to extract its first element (the
reference to the - myObject - object) and leave any other values for
later use in any call to the - fn - function.

I may have to ask the author himself;

You still may have to work out what the correct question is.

perhaps this is a code error in the draft.

No, the code is fine; a straight reproduction of a run-of-the-mill -
bind - implementation. Obviously the accompanying text is not very
effective as an explanation of what it going on here, but that is 'major
experts' for you.

Richard.- Hide quoted text -

- Show quoted text -

You were automatically quoted by google and it looks correct to
me.   There is just a single ">" in front of your lines and
">>" in front of where you quote me.

In any case, I simple took the google quote and did nothing
but reply below.  If there is any validity to your
concern, you will have to take it up with google.

I am trying, but do not yet quite understand your
explanation.  Could you spell it out bit by bit
more?

I agree with you that the expert did indeed
fail to explain the code, becuase he provides
no explanation.  You may have done a bit better,
but I am still unclear.  I think you may be able
to bring me "over the line" if you just detail
a bit more what happens.

(As with my last reply, I used the google
 quotinog of your post and did nothing
 to alter the way it was quoted.)- Hide quoted text -

- Show quoted text -

P.S. I do see what google is doing to you, Cornford,
and it just did it to me ABOVE. I will make sure
I make up for the terrible thing google does
ALTHOUGH THAT "quoted text" IS ABSOLUTELY EMPTY
and only a weird person would worry or take offense.

No offense.

Still, again, Cornford, I would be most appreciative
if you could detail you last response (if possible).
 

 
lorlarz
PostPosted: Fri Aug 29, 2008 3:44 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
On Aug 29, 9:34 am, "Richard Cornford" <Rich...@litotes.demon.co.uk>
wrote:
Quote:
lorlarz wrote:
On Aug 28, 6:16 pm, Richard Cornford wrote:
lorlarz wrote
snip
In the code sample below, how are arguments a legitimate
argument to Array.slice?

Function.prototype.bind = function(){
var fn = this, args = Array.prototype.slice.call(arguments),
object = args.shift();
return function(){
return fn.apply(object,
args.concat(Array.prototype.slice.call(arguments)));
};
};
var myObject = {};
function myFunction(){
return this == myObject;
}

myFunction.bind(myObject)();

Code that is intended to be read by humans ...
should be indented ...
snip
In the code above - arguments - is never an argument to
Array.slice. All occurrences of - arguments - as an argument
are as an argument to - Function.prototype.call -.

Richard.- Hide quoted text -

           ^^^^^^^^^^^^^^^^^^^^>> - Show quoted text -

   ^^^^^^^^^^^^^^^^^^^^^

I did _not_ write that final text. Why are you attributing words to me
that I did not write? That represents a serious breach of netiquette,
and is disingenuous at the very least.

This code is from a draft of a new JavaScript book

And the code is indented in that presentation (that is not a question,
and I don't need to see it in order to *know* that it *is* indented).

by a major expert.

YMMV

He is grabbing

What it the technical meaning of "grabbing" in javascript?

the arguments property of the function and passing
it as an argument to Array.prototype.slice

No he is not. That is not what the code above does, as I have already
told you once; at no point in the code above does an - arguments -
object get used as an argument to the - slice - method.

The contents of the arguments property that the function
receives is just the object myObject, so there seems to be
nothing to slice.

The - slice - method is used in order to transfer the values of the
'array index' properties of an - arguments - object to corresponding
properties of a newly created Array object. This allows - shift - to be
called on that Array in order to extract its first element (the
reference to the - myObject - object) and leave any other values for
later use in any call to the - fn - function.

I may have to ask the author himself;

You still may have to work out what the correct question is.

perhaps this is a code error in the draft.

No, the code is fine; a straight reproduction of a run-of-the-mill -
bind - implementation. Obviously the accompanying text is not very
effective as an explanation of what it going on here, but that is 'major
experts' for you.

Richard.

Let me see if I can spell the situation out for myself.
The call method looks for a real array and thus converts
the arguments object into a real array and then sends
the first argument of that resultant array
to the call method as the context
for "this" and IF there where any more arguments
(which in this example there are not), they would
be passed to the called function (Array.slice) IN
that context.

If this is correct, I guess my only remaining question
is what is the word "prototype" in this statement
var args = Array.prototype.slice.call(arguments); ??

I am doing all I can for myself. Can you
bring me "over the line" , Richard??
 

 
Lasse Reichstein Nielsen
PostPosted: Fri Aug 29, 2008 5:40 pm    Post subject: Re: How are arguments a legit argument to Array.slice?
       
lorlarz <lorlarz@gmail.com> writes:

Quote:
On Aug 29, 9:34 am, "Richard Cornford" <Rich...@litotes.demon.co.uk
wrote:
Richard.- Hide quoted text -

- Show quoted text -

You were automatically quoted by google and it looks correct to
me. There is just a single ">" in front of your lines and
">>" in front of where you quote me.

There is also the text "- Hide quoted text -" and "- Show quoted
text", which are attributed to Richard, and that wasn't there in his
message.

Quote:
In any case, I simple took the google quote and did nothing
but reply below. If there is any validity to your
concern, you will have to take it up with google.

Uhm, no. You are responsible for the tools you chose to use.
If Google Groups doesn't work satisfactory, you should take
it up with Google.

Quote:
I am trying, but do not yet quite understand your
explanation. Could you spell it out bit by bit
more?

I'm jumping into the middle here, but was the problem the
interpretation of
Array.prototype.slice.call(arguments)

This calls the "call" method on the function "Array.prototype.slice"
with the argument "arguments".

This gives approximatly the same effect as placing the function
as a method of the arguments object and calling it.

arguments.somename = Array.prototype.slice;
... arguments.somename();

just without actualy creating a property on the arguments object.


Quote:
(As with my last reply, I used the google
quotinog of your post and did nothing
to alter the way it was quoted.)

And it again introduced spurious text. Maybe you will have
to do something to avoid this, since nothing apparently
doesn't do the job :)

--
Lasse Reichstein Nielsen
DHTML Death Colors: <URL:http://www.infimum.dk/HTML/rasterTriangleDOM.html>
'Faith without judgement merely degrades the spirit divine.'
 

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