On Mar 23, 2011, at 8:33 AM, Tony Wang wrote:
Hi Smith ,
for my opinion , in your case
var doSomething = app.doSomething;
doSomething(); // boom if the 'this' references are left in tact.
I think it's a fault for invoker, If I am developing with it ,
I will not forget to use call or apply to the app when you are plan
to do something like that.
Like
var doSomething = app.doSomething;
doSomething.call(app);
I don't see a benefit to this. Storing a function reference that must
be call()ed from the host context is wasteful. app.doSomething() is
less code.
It's hard to design the function if you assume the invoker do KNOW
NOTHING but they want to DO ANYTHING.
And it do totally has different meaning for me between
app.doSomething() and doSomething().
My point is about 'this'. If there is one app object in the system,
there's no benefit in using 'this'. 'this' should always be the
same. So you can use 'this' for the sake of possibly creating another
app object in the future (in which case, it should be a prototype), or
you can use app and allow implementation code to use the methods via
local vars.
For example:
if (MyApp.utils.isWhoozit( someObject )) { ... }
vs
var isWhoozit = MyApp.utils.isWhoozit;
if (isWhoozit( someObject )) {
}
readability is not lost, and the code is shorter. There are
tradeoffs, sure. If readability is impacted, the namespaced function
can be referenced as though it required 'this'. That said, it's been
my experience that methods on static objects do not benefit from 'this'.
L
Best Regards,
Tony
2011/3/23 Luke Smith <[email protected]>
On Mar 23, 2011, at 6:43 AM, Poetro wrote:
2011/3/23 pnbv <[email protected]>:
Considering a single instance object:
app = {
foo: 'afoo',
bar: 'abar',
callbackLib: {
replyFoo: function () {
console.log(this.foo);
},
replyBar: function () {
console.log(app.bar);
}
},
doSomeThing: function (){
this.callbackLib.replyFoo.call(this);
this.callbackLib.replyBar();
}
}
app.doSomeThing();
What would be the preferred way of doing this (if there really is a
need for nested objects:)?
Thanks,
pedro
If you just want to get rid of the reference to this, you could do:
app = {
foo: 'afoo',
bar: 'abar',
callbackLib: {
replyFoo: function () {
console.log(app.foo);
},
replyBar: function () {
console.log(app.bar);
}
},
doSomeThing: function (){
app.callbackLib.replyFoo();
app.callbackLib.replyBar();
}
}
app.doSomeThing();
Although this would trigger errors in the following case:
bar = app;
app = {};
bar.doSomeThing();
As app is now no more.
There's a failure case either way.
var doSomething = app.doSomething;
doSomething(); // boom if the 'this' references are left in tact.
I find it preferable for non-instance collections of functions (i.e.
object literals with methods as shown) to reference the object
rather than 'this' as they are often utility functions or apply to
the application as a whole, and are therefore more useful as
function refs that can be passed around or assigned to shortcut
vars. Shortcut vars can be compressed better as well.
Short form: use 'this' in prototype methods, the containing var name
in "static" methods. As with most things, this is a guide, not a
rule.
L
--
Poetro
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