[Mono-osx] NObjective and Inheritance

[Martin Smith]

Hi Eugeny,

One other thing...

I was taking a look at the code and it doesnt look like HeaderAnalyzer is
used anymore.  It's looking like you extract all the method and property
information from the Objective-C runtime itself.  Is that true?

the HeaderAnalyzer.Analyze(..) method is commented out in ProfileBuilder.
Also this means that NObjectiveAST seems like it's not being used.

Thanks,
Martin



On Mon, Feb 9, 2009 at 6:39 AM, Eugeny Grishul <eugeny.grishul at gmail.com>wrote:

>
> Hi,
> Thanks for deep code review =)
>
> Weaver pros and cons:
> 1) without inheritance proxy assemblies will be about 60M due to duplicated
> methods
> 2) it will be used for Objective-C property accessors for same goal
>
> Cons:
> 1) code produced by weaver is not verifiable. By spec CLI itself does not
> allow for value type inheritance:
>
> 8.9.7.
> ...
> 3. A value type does not inherit; rather the base type specified in the
> class definition defines the
> base type of the boxed type.
> 4. The base type of a boxed type shall not have any fields.
>
> 8.9.10.
> In their unboxed form value types do not inherit from any type. Boxed value
> types shall inherit directly from
> System.ValueType unless they are enumerations, in which case, they shall
> inherit from System.Enum. Boxed
> value types shall be sealed.
>
> My approach is a violation of the spec. If you run "peverify" on the
> assembly with one value type inheriting from another, it will tell you as
> much =) If mono won't support value-type inheritace in future it will be
> bug
> in ther JIT coz CLR implementation actually ALLOWS it.
> 2) Current Mono VES implementation have a bug related ot value type
> inheritance and to workaround it don't allow objc proxies to be boxed.
> Following code will crash JIT:
>
> public void ButtonPressed( NSButton sender )
> {
>    Console.WriteLine( "Pressed {0}", sender );
> ...
> ...
>
> And workaround:
> public void ButtonPressed( NSButton sender )
> {
>    Console.WriteLine( "Pressed {0}", sender.ToString() );
> ...
> ...
>
> About NObjectiveAST - it works like NRefactory and able to parse and save
> AST tree to file. But if you want to extend interoping abilities of
> resulting code then you should modify HeaderAnalyzer (
>
> http://code.google.com/p/nobjective/source/browse/trunk/ProxyGenerator/HeaderAnalyzer.cs
> ) which is not part of NObjectiveAST. The goal of mine bridge is
> Objective-C
> interop so I'll not plan to add support for automatical P/Invoke
> generation.. My friend's dimpoma thesis is related with automatical
> P/Invoke
> generation (he will use NObjectiveAST and test his work on creating Qt
> bindings with full code coverage) and may be after 5 months of his work we
> will see brialliant project..or not =) Anyway you can make patch and help
> to
> improve project =)
>
> WBR,
> Eugeny Grishul
>
>
> Martin Smith-8 wrote:
> >
> > Hello,
> >
> > I was looking at the NObjective source code, and noticed that that
> > basically
> > all the proxies are generated as structs.  The compiled assembly then
> gets
> > passed to a code weaver which fills in the Objective-C class inheritance
> > structure. The code weaver basically uses Mono.Cecil to make structs
> > support
> > inheritance.
> >
> > I guess this works, but the thing I'm wondering is: is it safe te rely on
> > the fact that the mono runtime can actually support inheritance for value
> > types?  Is this something that's supposed to be supported by the CLI but
> > just isnt supported by C#?  I'm assuming that there would be some serious
> > issues if all the proxies weren't the same size (i.e. with only an IntPtr
> > as
> > the instance data).
> >
> > At any rate, cheers Eugeny.  You've created a pretty impressive layer
> > here.
> > Have you thought about extending NObjectiveAST to suport interoping some
> > of
> > the C-based functions (for example, NSMakeRect, or the CGContext*
> > methods).
> >
> > Thanks again Eugeny for such great code!
> > Martin
> >
> > _______________________________________________
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> >
> >
>
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