Properties and references in Python components, was: [C++] Python extension available

[Jean-Sebastien Delfino <js...@apache.org>]

Andrew Borley wrote:
[snip]
> In other news, I have just added in support for properties to the Python
> extension:
> - A composite with a property defined in a component and the associated
> .componentType file:
>    <component name="DivideComponent">
>        <implementation.python module="DivideImpl" scope="composite"/>
>        <property name="doRounding">true</property>
>     </component>
>
> <componentType
> ...
>    <property name="doRounding" type="xsd:boolean"/>
> </componentType>
>
> Is automatically instantiated and assigned the property value in the 
> python
> implementation module:
>
> def divide(val1, val2):
>    result = float(val1) / float(val2)
>    print "Python - DivideImpl.divide " + str(val1) + " / " + str(val2) 
> + "
> = " + str(result)
>
>    # Use the doRounding property
>    if doRounding:
>        result = round(result)
>        print "Python - DivideImpl.divide is rounding the result to " +
> str(result)
>
>    return result
>
>
> Cheers
>
> Andy
>

Andy, this is nice. What do you think about going just one small step 
further to make  ComponentType definitions optional, and basically 
define the Python variable automatically when it is configured as a 
property or a reference on the component definition?

As a scripting developer I am not used to declare my variables ahead of 
time, they are just created automatically once I assign a value to them. 
Doing this would be in the same spirit: you get a variable created for 
you when you configure/assign its value on the component declaration and 
the scripting developer does not need to write ComponentType files to 
declare things that he usually doesn't like to declare...

This would just require a small change to ModelLoader.cpp and your 
PythonImplementation.cpp, for references we would do the following:
- ModelLoader would call a new needReferenceType(name) method or a 
findReferenceType(string name, createNew=true) method on the 
ComponentType (your PythonImplementation) and in this method you would 
create the ReferenceType.
- We would follow a similar scheme for properties.

I had started to implement that scheme for Ruby (see 
RubyImplementation::findReferenceType() in revision r442461 or 
RubyImplementation.cpp) then backed it out as in Ruby you usually 
declare your public attributes/properties. But I think that this would 
apply well to languages like Python and Javascript.

Let me know what you think.

-- 
Jean-Sebastien


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Re: Properties and references in Python components, was: [C++] Python extension available

[Jean-Sebastien Delfino <js...@apache.org>]

Andrew Borley wrote:
> On 9/15/06, Jean-Sebastien Delfino <js...@apache.org> wrote:
>>
>> Andrew Borley wrote:
>> [snip]
>> > In other news, I have just added in support for properties to the 
>> Python
>> > extension:
>> > - A composite with a property defined in a component and the 
>> associated
>> > .componentType file:
>> >    <component name="DivideComponent">
>> >        <implementation.python module="DivideImpl" scope="composite"/>
>> >        <property name="doRounding">true</property>
>> >     </component>
>> >
>> > <componentType
>> > ...
>> >    <property name="doRounding" type="xsd:boolean"/>
>> > </componentType>
>> >
>> > Is automatically instantiated and assigned the property value in the
>> > python
>> > implementation module:
>> >
>> > def divide(val1, val2):
>> >    result = float(val1) / float(val2)
>> >    print "Python - DivideImpl.divide " + str(val1) + " / " + str(val2)
>> > + "
>> > = " + str(result)
>> >
>> >    # Use the doRounding property
>> >    if doRounding:
>> >        result = round(result)
>> >        print "Python - DivideImpl.divide is rounding the result to " +
>> > str(result)
>> >
>> >    return result
>> >
>> >
>> > Cheers
>> >
>> > Andy
>> >
>>
>> Andy, this is nice. What do you think about going just one small step
>> further to make  ComponentType definitions optional, and basically
>> define the Python variable automatically when it is configured as a
>> property or a reference on the component definition?
>>
>> As a scripting developer I am not used to declare my variables ahead of
>> time, they are just created automatically once I assign a value to them.
>> Doing this would be in the same spirit: you get a variable created for
>> you when you configure/assign its value on the component declaration and
>> the scripting developer does not need to write ComponentType files to
>> declare things that he usually doesn't like to declare...
>
>
> +1 for this. I don't really get why we need the .componentType file 
> when the
> info is already in the .composite.

Yes, ComponentTypes are very similar to Classes (and Components to 
Objects) so they make most sense when you work with a OO language with 
Classes and Objects. In your Python scripting environment you can define 
properties directly on Objects so ComponentTypes are less useful.

> This would just require a small change to ModelLoader.cpp and your
>> PythonImplementation.cpp, for references we would do the following:
>> - ModelLoader would call a new needReferenceType(name) method or a
>> findReferenceType(string name, createNew=true) method on the
>> ComponentType (your PythonImplementation) and in this method you would
>> create the ReferenceType.
>> - We would follow a similar scheme for properties.
>>
>> I had started to implement that scheme for Ruby (see
>> RubyImplementation::findReferenceType() in revision r442461 or
>> RubyImplementation.cpp) then backed it out as in Ruby you usually
>> declare your public attributes/properties. But I think that this would
>> apply well to languages like Python and Javascript.
>>
>> Let me know what you think.
>
>
> It sounds good to me - do you have time to implement this? If not I'll 
> have
> a go - I didn't want to touch any of the core code for the extension, 
> but I
> don't mind getting stuck in :)
>
> Cheers
> Andy
>

Great. I can help if you have any questions but if you are interested in 
digging into the core code please feel free to go ahead and make the 
changes you need :) The more people know the core code the better IMO.

-- 
Jean-Sebastien


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Re: Properties and references in Python components, was: [C++] Python extension available

[Andrew Borley <aj...@gmail.com>]

On 9/15/06, Jean-Sebastien Delfino <js...@apache.org> wrote:
>
> Andrew Borley wrote:
> [snip]
> > In other news, I have just added in support for properties to the Python
> > extension:
> > - A composite with a property defined in a component and the associated
> > .componentType file:
> >    <component name="DivideComponent">
> >        <implementation.python module="DivideImpl" scope="composite"/>
> >        <property name="doRounding">true</property>
> >     </component>
> >
> > <componentType
> > ...
> >    <property name="doRounding" type="xsd:boolean"/>
> > </componentType>
> >
> > Is automatically instantiated and assigned the property value in the
> > python
> > implementation module:
> >
> > def divide(val1, val2):
> >    result = float(val1) / float(val2)
> >    print "Python - DivideImpl.divide " + str(val1) + " / " + str(val2)
> > + "
> > = " + str(result)
> >
> >    # Use the doRounding property
> >    if doRounding:
> >        result = round(result)
> >        print "Python - DivideImpl.divide is rounding the result to " +
> > str(result)
> >
> >    return result
> >
> >
> > Cheers
> >
> > Andy
> >
>
> Andy, this is nice. What do you think about going just one small step
> further to make  ComponentType definitions optional, and basically
> define the Python variable automatically when it is configured as a
> property or a reference on the component definition?
>
> As a scripting developer I am not used to declare my variables ahead of
> time, they are just created automatically once I assign a value to them.
> Doing this would be in the same spirit: you get a variable created for
> you when you configure/assign its value on the component declaration and
> the scripting developer does not need to write ComponentType files to
> declare things that he usually doesn't like to declare...


+1 for this. I don't really get why we need the .componentType file when the
info is already in the .composite.


This would just require a small change to ModelLoader.cpp and your
> PythonImplementation.cpp, for references we would do the following:
> - ModelLoader would call a new needReferenceType(name) method or a
> findReferenceType(string name, createNew=true) method on the
> ComponentType (your PythonImplementation) and in this method you would
> create the ReferenceType.
> - We would follow a similar scheme for properties.
>
> I had started to implement that scheme for Ruby (see
> RubyImplementation::findReferenceType() in revision r442461 or
> RubyImplementation.cpp) then backed it out as in Ruby you usually
> declare your public attributes/properties. But I think that this would
> apply well to languages like Python and Javascript.
>
> Let me know what you think.


It sounds good to me - do you have time to implement this? If not I'll have
a go - I didn't want to touch any of the core code for the extension, but I
don't mind getting stuck in :)

Cheers
Andy