How to allow My class to add custom fields and properties by other class on the fly

Question

1.00/5 (1 vote)

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C#

Windows

I want to allow new fields to be added in my class by calling class.

Posted 7-Jul-11 22:35pm

whitehaker

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4 solutions

Solution 4

As SAKryukov mentions, there could be a simpler solution - obviously depending on what you are doing. Could it be that you are looking for attached properties[^]

Best regards
Espen Harlinn

Posted 8-Jul-11 1:04am

Espen Harlinn

Comments

Sergey Alexandrovich Kryukov 10-Jul-11 1:11am

Wait a minute? WPF? However, it's not specified. Or did you mean using the engine without the rest of WPF (I'm pretty sure it would be possible)? Interesting idea anyway, my 5.
--SA

Espen Harlinn 10-Jul-11 6:57am

It's one of the few other ways I'm able to make sense out of the question. If this is what he want - it makes sense, but it could have been better formulated.

Code injection, as you pointed out, is the other :)

Sergey Alexandrovich Kryukov 12-Jul-11 16:30pm

Agree, only I don't know where I pointed out "code injection". I don't think I did.
Thank you.
--SA

Espen Harlinn 12-Jul-11 16:52pm

That's what you do when you modify an existing class using emit :)

Solution 3

I am fairly sure you don't actually want what you say you want. Properties added dynamically could not possibly be accessed in compiled code (since you wouldn't know how to reference them). So there is almost no point in actually creating properties. What you want is somewhere for a calling class to store information against names. You can do that with a Hashtable.

Posted 7-Jul-11 23:22pm

BobJanova

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Christian Graus · Accepted Answer · 2011-07-07T22:39:00

Solution 1

This[^] will do it, if anything will.

Posted 7-Jul-11 22:39pm

Christian Graus

Comments

Tarun.K.S 8-Jul-11 5:11am

Nice article. 5+

whitehaker 8-Jul-11 7:08am

Thanks alot good article. my 5

fjdiewornncalwe 8-Jul-11 7:18am

I like that link. I don't think I ever saw that article. +5

Sergey Alexandrovich Kryukov · Accepted Answer · 2011-07-07T22:45:00

Solution 2

The key here is using System.Reflection.Emit.
See http://msdn.microsoft.com/en-us/library/3y322t50.aspx[^].

This is one of the very difficult topics. Do you really want what are you asking about? Could you share your ultimate goal of it? Most likely much more simple approach could be considered.

—SA

Posted 7-Jul-11 22:45pm

Sergey Alexandrovich Kryukov

Updated 7-Jul-11 22:59pm

v2

Comments

Christian Graus 8-Jul-11 4:47am

Yes, there is no doubt that if he adds properties, they won't be strongly typed, or easily accessed.

Sergey Alexandrovich Kryukov 8-Jul-11 4:56am

Absolutely! As I say, this is difficult. True, emitting properties themselves is still all right; using them would be a real pain.
--SA

Tarun.K.S 8-Jul-11 5:11am

Good answer! 5+

Sergey Alexandrovich Kryukov 8-Jul-11 5:14am

Thank you, Tarun.
--SA

Espen Harlinn 8-Jul-11 7:02am

My 5

Sergey Alexandrovich Kryukov 8-Jul-11 8:25am

Thank you, Espen.
--SA

whitehaker 8-Jul-11 7:10am

In loosly type language like PHP, I could do this which allowed me to easily extend the class just like an array.

Sergey Alexandrovich Kryukov 8-Jul-11 8:26am

Yes, so what? You cannot compare compiled and scripted languages.
--SA