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Message-ID: <4147811.bbFqFoj25p@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <cljs@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Tue, 21 Feb 2012 12:58:41 +0100
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Subject: Re: onclick=function(){obj.meth()}
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Richard Cornford wrote:

> Puzzled wrote:> On Mon, 20 Feb 2012 23:17:42 +0100,
>> This is what I'm trying to do:
>>
>> onclick = "this.some_method_identifier( arg, arg )"
> 
> That is meaningless in javascript terms precisely because the value of
> the - this - keyword is not decided at this point.

Incorrect.  `this' in an event-handler *attribute* value is and always has 
been a reference to the DOM object representing the element having that 
attribute value.

However, issues arise if `some_method_identifier' is not a stand-in for a 
built-in method of that DOM object or an object in its prototype chain.  A 
DOM object is a host object, and per the ECMAScript Language Specification 
the algorithms of the Specification, including the `[[Put]]' and `[[Get]]' 
algorithms to set and retrieve property values, respectively, do not need to 
be implemented as specified.  IOW:

  With host objects, all bets are off.
    -- (attributed to) Lasse Reichstein Nielsen
 
>> and should be able to grasp that when I use it in a binding,
> 
> Presumably you are using "terp" as an abbreviation for interpreter.
> 
> In javascript the value of the - this - keyword is (always and only)
> decided at runtime, 

Which is precisely why the followed approach may work, given the right 
method call. 

> so the interpreter cannot know what the value will be at the time of
> tokenising/parsing/compiling the code.

It does not have to in this case.

>> I thought the proxy and the anon function were the required magic, be
>> evidently not so, so now I'm back where I started, neck deep in
>> confusion and ignorance.
> 
> Computer programming is about understand enough to take control, which
> is the antithesis of  'magic'.

ACK.


PointedEars
-- 
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a Web page appears to be yearning for the bad old days, before the Web,
when you had very little chance of reading a document written on another
computer, another word processor, or another network. -- Tim Berners-Lee