[Laszlo-dev] how do I check for the existence of an attribute?

[Sarah Allen]

So, how do you add something?  is it myview.capabilities['mic'] =  
true ... or ?

On Feb 10, 2009, at 11:31 AM, P T Withington wrote:

> Max added it.  I guess we need to document it.  It is for asking  
> things like:  can I do rotation or tinting (which only works on some  
> runtimes), so it seemed like whether there was a microphone or not  
> ought to be determined using this.
>
> On 2009-02-10, at 13:12EST, Sarah Allen wrote:
>
>> I notice that there is a capabilities property in the v4 doc for  
>> view (but no description):
>> http://www.openlaszlo.org/lps4/docs/reference/LzView.html
>>
>> but not in the 4.2 doc:
>> http://www.openlaszlo.org/lps4.2/docs/reference/
>>
>> It sound promising though...
>>
>> Sarah
>>
>> On Feb 10, 2009, at 5:57 AM, Sarah Allen wrote:
>>
>>> what is a views 'capabilities' list?
>>>
>>> On Feb 10, 2009, at 4:32 AM, P T Withington wrote:
>>>
>>>> Shouldn't the existence of a microphone be in the view's  
>>>> `capabilities` list?
>>>>
>>>> On 2009-02-09, at 21:34EST, Max Carlson wrote:
>>>>
>>>>> Videoview.mic could be initialized to false and you could test  
>>>>> for that value explicitly, to differentiate against null.
>>>>>
>>>>> I'll try that with the change you sent me for review...
>>>>>
>>>>> Sarah Allen wrote:
>>>>>> The microphone has the following code:
>>>>>>        // Use duck typing to check for the existence of the
>>>>>>        // _setMic method, instead of checking if the
>>>>>>        // immediateparent is an instance of videoview, to avoid
>>>>>>        // loading the videoview class if it's not needed.
>>>>>>        if (immediateparent['_setMic']) {
>>>>>>            immediateparent._setMic(this);
>>>>>>        }
>>>>>> This doesn't work because videoview no longer has a setMic  
>>>>>> method.  Instead, we're supposed to use setAttribute...
>>>>>> However, then we would need to write:
>>>>>>        if (immediateparent['mic']) {
>>>>>>            immediateparent.setAttribute('mic', this);
>>>>>>        }
>>>>>> except that won't work since mic is intialized to null and  
>>>>>> immediateparent['mic'] will evaluate to false.
>>>>>> Any syntax gurus in the house?
>>>>>> Thanks,
>>>>>> Sarah
>>>>>
>>>>> -- 
>>>>> Regards,
>>>>> Max Carlson
>>>>> OpenLaszlo.org
>>>>
>>>
>>
>