C# Properties

[Jeff Odell]

Where does it say a class' attributes have to be implemented as storage locations?  If I have an internal collection, and I have an property returning it's count, are you Ok with that as an attribute as it refers to something stored within the object?

When I expect the user of the class to get or set a single value in an object, I implement a property.   To the user it is transparent how that state is maintained.  When I want an action to occur, I create a method. The user can then expect some action to occur.

So I still want propertied to represent a UML attribute of an object.  

I only asked for the option so we could all be happy.  

[ceatley]

I also use properties as though they were attributes, but they have a direct one - to - one behavior correlation with operations.

if
public type property
{
 get {
  any code that returns a value of type
}
 set {
   any code that changes the value of a variable of type
}
}
then    
  type x = property is <=> with type x = get_property();

and
  property = x is <=> with set_property(x);

The point is that properties also have the same limitations as operations  (ie can't be used as ref and out parameters)
98% of the time it doesn't make a difference, but when it does, it will bite you.   There are several other places where you will get into trouble if you try to use a property as an attribute.  I have spent more then a little time changing code when I forgot and used properties incorrectly.

I therefore think that the way the reverse engineering is done now, gives a better view of what is happening.  Sometimes, information hiding isn't the best answer.

Chuck

[Hans]

But: Every field is translated into IL-properties upon compilation.

[Jeff Odell]

I just have to disagree - mapping a property directly to a field is just one implementation of an attribute.  The fact that I might to write code to derive the value of an attribute, and that code might be wrong, doesn't change that.

In my mind, a property is never an operation, because if it does something, rather than just change the state of something, I code it as an operation anyway - i.e. a C# method rather than a property.

Again - I just want the option to map a property to an attribute in EA.  I had asked for the ability to flip a switch in code generation to set the default.  Perhaps this should only be the default, with the ability to set individual properties to appear as attributes or operations based on a tag or something.  This would allow you the flexibility to decide which properties are attributes and which are functions.  I would be disinclined to use that feature - to me they would all be attrbiutes - but if you wanted to designate them you'd have that flexibility.

jlo

[Eve]

Hi,

I've noted that an option to reverse engineer C# properties as properties or methods would be appreciated.  The same would I assume apply to VB.Net although that hasn't been discussed yet.

I'll look into how hard it would be to do this along with everything else that I am doing.  Default behaviour would probably be the existing behaviour.

Simon

[inthere]

To me it is clear. An attribute is something that is operated on by operations. An operation is something that can modify the state of an attribute. A C# property can operate on an incoming or outgoing attribute value, therefore is must fall under the operation category.

Paul

[ceatley]

OK, if a property is modeled as an attribute, how is the code generated?  Also, if a property model named Count accesses a private attribute named count, how do you model the association?

[Jeff Odell]

You can already create properties in the attribute section of the model - create an attribute and attach the "property" stereotype.  When you generate code you get:

Code: [Select]


public string Ssn {
   //read property
   get{;}
   //write property
   set{;}
}


That works fine for me.  

What I'd like is the opportunity to have reverse engineering reversing properties so they end up in the attribute section.

I don't understand the association question.

[Jeff Odell]

Simon -

Yes - I'd really like the option for the reverse engineering to place the the properties in the attributes section.  Although I was thinking C# I do occasionally work in VB also so that would be great.

jlo

[mikewhit]

Note that you can specify a class attribute to be 'derived' (which is close-ish to a C# property) which makes it display with a '/'.

I don't know how this affects code generation.