Should have a way to tell the picker to get its initial value from a DOM element of the page it's on

My initial idea was to add an optional 'get_initial_value_from' attribute to the Picker so that callsites would be able to specify the DOM element from where the Picker would get the initial value for the search input.

However, Maris didn't like that idea because he thinks that'd make lazr-js too tied to LP's implementation (as the DOM node would have to provide a 'value' attribute), so he suggested adding this to an Y.lp.Picker, to be used in LP instead of the raw Picker.

The others that were present at the lazr-js sprint in Dallas thought it'd be better to add the 'get_initial_value_from' attribute to the picker rather than adding it to a custom LP picker as that's a feature that's likely to benefit others.

Instead of a 'get_initial_value' attribute, I suggest calling the attribute simply 'initial_value'. The user sets it in the constructor.

To support your case, I suggest it support the user setting the value as a function. If initial_value is a function, then getting it will return that function's value.

// Support setting the initial value as a static text string
new Y.Picker({
  initial_value: 'foobar',
  input: 'input#baz'
});

// Support computing the initial value using a function
new Y.Picker({
  initial_value: function(input) {
    // Grabs the initial value from the DOM. The input node is passed in as a parameter to make things easier for the user.
    return input.get('value');
  },
  input: 'input#baz'
});

On Thu, 2009-12-10 at 13:21 +0000, Māris Fogels wrote:
> Instead of a 'get_initial_value' attribute, I suggest calling the
> attribute simply 'initial_value'. The user sets it in the constructor.
>
> To support your case, I suggest it support the user setting the value as
> a function. If initial_value is a function, then getting it will return
> that function's value.

The problem with this solution is that I then need to duplicate this
function in all callsites that make use of the feature, which is not
nice.

Bjorn suggested a different approach, which is simpler to use and yet
generic enough[1]. What do you think of that? Maybe we should move
this discussion to the merge proposal?

[1] https://code.edge.launchpad.net/~salgado/lazr-js/bug-482235/+merge/15940