Here is your orig snippet rewritten to use the rescope function I pasted:
var datascape = {
'mouseX': 0,
'myInterval': 0,
'create': function(){
$('#datascape').bind('mousemove', rescope(this, function(e)
{
this.mouseX = e.pageX;
})).bind("mouseover", rescope(this, function()
{
this.myInterval = setInterval(rescope(this, "move"), 200);
})).bind("mouseout", rescope(this, function()
{
clearInterval(this.myInterval);
}));
},
'move': function(){
$.log('datascape.move : mouseX = ' + this.mouseX);
}
}
Though I didn't test it ...
You are calling window.datascape.move still in the "window scope",
when you want the scope (this) to be retained throughout your function
calls. Saving a ref to it (var self = this) and accessing it in a
function is still the solution. rescope is just that wrapped in a
function for sugar (more or less). By passing 'this' to the rescope()
function, you are effectively doing the same as self = this;
function(){ self.foo(); } .. I find it much cleaner (the non-stripped
version of rescope() allows for passing an ambigious number of
parameters to the rescope'd function) and easier to work with when I'm
explicitly setting the execution scope.
Regards,
Peter Higgins
On Fri, Jan 2, 2009 at 8:06 PM, Alexandre Plennevaux
<aplennev...@gmail.com> wrote:
>
> Michael, did you know that i 'm becoming a big fan of your explanations?
>
> if i follow your explanation correctly, this should have worked, isn't it ?
>
> datascape.myInterval = setInterval(window.datascape.move,400);
>
> Yet it didn't. I guess i 'm kind of assimilating the javascript window
> object to actionscript's _root object, and that assumption is probably
> plain wrong :)
>
>
> On Fri, Jan 2, 2009 at 11:49 PM, Michael Geary <m...@mg.to> wrote:
>>
>> Hi Alexandre,
>>
>> Don't go adopting a coding practice just because of a single mailing list
>> message. :-)
>>
>> There's nothing wrong with quoting property names in an object literal, but
>> the majority of experienced JavaScript programmers do not quote them except
>> when necessary. As an example, browse through the jQuery source code:
>>
>> http://ajax.googleapis.com/ajax/libs/jquery/1.2.6/jquery.js
>>
>> Most of the property names in the code are not quoted, except for those few
>> that are invalid identifiers or reserved words.
>>
>> Regarding setTimeout and setInterval, a minor nitpick on terminology:
>> "setTimeout and setInterval scope the called function to the window object".
>> Actually, the *scope* of the called function is determined by its position
>> in the source code. JavaScript uses lexical scoping, where a nested function
>> can directly refer to variables declared in outer functions or in the global
>> scope. That's why your setInterval callback is able to use your thisObj
>> variable, because the interpreter follows the scope chain from the inner
>> function up to the outer function and finds the variable there.
>>
>> What you're talking about is the value of "this" in the setInterval
>> callback. setInterval and setTimeout call your callback function as a method
>> of the global object (which is the window object in a browser). Or another
>> way to put it is that they don't call the function as a method of any object
>> at all, and by default "this" is set to the global object.
>>
>> In any case, terminology nitpicks aside, your code is the right way to solve
>> the problem! :-)
>>
>> -Mike
>>
>>> From: Alexandre Plennevaux
>>>
>>> hi donb, according to a lengthy discussion we had on this
>>> mailinglist yesterday the quotes are good practice. see:
>>> http://groups.google.com/group/jquery-en/msg/821f4eb134c51d3d
>>> (is is just one message on a 31-long thread, if u have time
>>> ,read the whole thread it is interesting )
>>>
>>> As for this issue after extensive googling i found out that
>>> setTimeout and setInterval scope the called function to the
>>> window object, not the object the setinterval is called in.
>>>
>>> Therefore here is how to do it:
>>>
>>> var datascape = {
>>> 'mouseX': 0,
>>> 'myInterval': 0,
>>> 'create': function(){
>>>
>>> var thisObj = this; //<-- store this object instance in a variable
>>>
>>> $('#datascape').bind('mousemove', function(e)
>>> {
>>> this.mouseX = e.pageX;
>>> }).bind("mouseover", function()
>>> {
>>> datascape.myInterval = setInterval(function() {
>>> thisObj.move(); }, 1000); // <-- use the vairable
>>> referencing the instance
>>>
>>> }).bind("mouseout", function()
>>> {
>>> clearInterval(datascape.myInterval);
>>> });
>>> },
>>>
>>> 'move': function(){
>>> $.log('datascape.move : mouseX = ' + this.mouseX);
>>> }
>>> }
>>>
>>> On Thu, Jan 1, 2009 at 3:46 PM, donb
>>> <falconwatc...@comcast.net> wrote:
>>> >
>>> > You should change 'move' to move (remove apostrophes).
>>> >
>>> >
>>> > On Jan 1, 9:01 am, "Alexandre Plennevaux" <aplennev...@gmail.com>
>>> > wrote:
>>> >> Hello mates,
>>> >>
>>> >> i have an object datascape which among other things, contains a
>>> >> property storing the mouse position, and a function that uses that
>>> >> property. Inside another method i
>>> >>
>>> >> var datascape = {
>>> >> 'mouseX': 0,
>>> >> 'myInterval': 0,
>>> >> 'create': function(){
>>> >> $('#datascape').bind('mousemove', function(e)
>>> >> {
>>> >> this.mouseX = e.pageX;
>>> >> }).bind("mouseover", function()
>>> >> {
>>> >> this.myInterval = setInterval(this.move, 200);
>>> >>
>>> >> }).bind("mouseout", function()
>>> >> {
>>> >> clearInterval(this.myInterval);
>>> >> });
>>> >> },
>>> >>
>>> >> 'move': function(){
>>> >> $.log('datascape.move : mouseX = ' + this.mouseX);
>>> >> }
>>> >>
>>> >> }
>>> >>
>>> >> Yet the script does not work:
>>> >> firebug console points at the setInterval call, saying:
>>> >>
>>> >> useless setInterval call (missing quotes around
>>> >> argument?)http://localhost/prototype/_js/frontend/proto.03.js
>>> >> Line 172
>>> >>
>>> >> can someone help me / explain what i'm doing wrong ?
>>> >>
>>> >> Thank you,
>>> >>
>>> >> Alexandre
>>> >>
>>> >> PS: to all jquerians: happy 2009 !!
>>>
>>
>>
>
