Fast Property setting: DynamicMethod Problem

04-13-2008 6:48 PM |

For some reason, in SilverLight, our calls to DynamicMethod fail.

It reports the following:  "Attempt to access the method failed: System.Reflection.Emit.DynamicMethod..ctor(System.String, System.Type, System.Type[], System.Type, Boolean)"

We really need this to work because setting properties on Lists of objects using regular reflection is WAY too slow.

Does anyone know what's going on here?  BTW, thsi code works perfectly on the server(permission problem?).

Re: Fast Property setting: DynamicMethod Problem

04-13-2008 7:34 PM |

Access to the .ctor overloads that take the bool skipVisibility option are restricted (because turning off member visibility checks would be a security risk).  If you're passing 'false' for this bool, use one of the overloads that don't take the parameter instead.

Re: Fast Property setting: DynamicMethod Problem

04-13-2008 11:02 PM |

Yes, I was passing 'false' to the visibility check, so I removed it, and I still get the message, however, it references the new constructor.

Additional information: Attempt to access the method failed: System.Reflection.Emit.DynamicMethod..ctor(System.String, System.Type, System.Type[], System.Type)

The strange thing is that both constructors compile just fine, and only die at runtime.

Help....

Re: Fast Property setting: DynamicMethod Problem

04-14-2008 12:13 AM |

Make sure the constructor you use is not marked with the SecurityCritical attribute. I think the only constructor available to user code is

DynamicMethod(string name, Type returnType, Type[] parameterTypes)

DynamicMethods created from user code cannot have an owner, but you can still create a delegate that is bound to an object.

Re: Fast Property setting: DynamicMethod Problem

04-14-2008 3:02 AM |

Thanks Jabb, that constructor works.

Now I only have to modify my code since the type is unknown in the delegate now.

Sam...

Re: Fast Property setting: DynamicMethod Problem

04-14-2008 8:33 PM |

I've looked at emitting code in a partially trusted environments, and it isn't pretty. 

Can anyone at MSFT confirm that we this will be the only way to get faster property get/set access in SL2?

Thanks,

Sam...

Re: Fast Property setting: DynamicMethod Problem

04-15-2008 2:47 PM |

Yi-Lun Luo - MSFT:

Hello, can you give more details about your scenario? What do you mean by setting properties on lists of objects? Why do you think emitting is faster than reflection? Can you show some code?

Here's the case.

1.  I query the server, and it returns XML
2.  The DataGrid won't let me set the cells without an object, so I have to create a collection of objects
3.  Each object has to have the properties/fields set by reflection

Now if I use SetProperty on each object, it takes minutes when there are a lot of fields, and on the order 2000 objects.

If I use DynamicMethod and gnerate a delegate for each field/property, it takes milliseconds.

This is a well known problem, and was the reason DynamicMethod has been a popular solution.  My problem is that SilverLight doesn't support binding DynamicMethod to a Class, and therefore to use it, you have to create another AppDomain, and then unload it.

So my queston was to find out if MSFT is going to support the constructor that binds to a class, or remain with the anonymous creation.

Thanks,

Sam...

Re: Fast Property setting: DynamicMethod Problem

04-15-2008 2:56 PM |

I forgot one thing.

The reason I need reflection is to free myself from coding each datagrid every time the object changes.

Sam...

Re: Fast Property setting: DynamicMethod Problem

05-28-2008 3:34 AM |

I got bitten by the DynamicMethod constructor also. I hate to say this, but really, why the heck we need this securitycitical attribute anyhow?

Anyway, took me hours to figure out the security model, I called a constructor with SecuritySafeCritical attribute, that worked. But the type I built does not work anymore.  I use System.Reflection.TypeBuilder to build a type, call its constructor to create an instance.

As I used the same code under desktop .net framework, it works fine. I port it to silverlight almost without change anything. The compilation goes while. But the dynamically built type does not work anymore. Is there any restrictions to this also?

 This is getting so frustrating, even I know it's just beta.

Calvin