[Development] why is QJSEngine not modifying metaObject

Hausmann Simon Simon.Hausmann at theqtcompany.com
Wed Feb 11 19:50:42 CET 2015


Hi,

The brute force way is to add this feature to the engine at the expense of performance, memory consumption and maintenance :)

Today you can invoke Javascript defined functions by simply getting the function as a property via QJSValue and call() it.


Simon

  Original Message
From: Rees, Kevron
Sent: Wednesday, February 11, 2015 17:18
To: Hausmann Simon
Cc: Thiago Macieira; development at qt-project.org
Subject: Re: [Development] why is QJSEngine not modifying metaObject


On Wed, Feb 11, 2015 at 12:03 AM, Hausmann Simon
<Simon.Hausmann at theqtcompany.com> wrote:
> Hi,
>
> Kind of :) It works on a type level. So a new type is defined with new methods and a new meta object is defined. But it doesn't use a mechanism where a new meta object is created each time a method is added.
>
> If we move the current engine over to generate meta objects from internal classes then perhaps we could create the meta objects on demand and batch them. That would make the example at hand work.
>

This sounds desirable.

> Of course this could also be implemented by brute force, but I'm not sure it is worth it.
>

Can you elaborate on this brute force method?  Is there another way to
get the internal JS class metadata in c++?

> Simon
>
>   Original Message
> From: Thiago Macieira
> Sent: Wednesday, February 11, 2015 08:35
> To: development at qt-project.org
> Subject: Re: [Development] why is QJSEngine not modifying metaObject
>
>
> On Wednesday 11 February 2015 07:11:26 Hausmann Simon wrote:
>> Hi,
>>
>> The short answer to your question is that the meta object system isn't
>> really designed for this. In theory this could be implemented but it would
>> come at a high cost for something that rarely happens. The qml engine
>> supports this, but in qml this happens at type compilation time, not fully
>> dynamic.
>
> Wasn't this how QML1 worked?
> --
> Thiago Macieira - thiago.macieira (AT) intel.com
>   Software Architect - Intel Open Source Technology Center
>
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