Cast Action<T> to Action<object> [modified]
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I understand that I should avoid boxing & un-boxing (and I do want to, and I do it everywhere), in this case it's not an option. Bit of a complex scenario I'll have to explain (and the code is part of a 5 000 file solution), but I'm quite irritated that this is disallowed, I thought polymorphism / covariance / contravariance is exactly about this...
____________________________________________________________ Be brave little warrior, be VERY brave
It's a design issue and it makes sense when you think about it. If you want to use a collection of type object, then use ArrayList. The generic List is a strongly typed version of ArrayList, so if strong typing is not required, use ArrayList.
"You get that on the big jobs."
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Adriaan Davel wrote:
this
object x = 1;worksThat wraps your value-type with a reference-type; your number is actually stored in the object, but a number is not an object itself.
I are Troll :suss:
In .net, everything is an object. :-D
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Because it just can't. If asked questions such as this I like to mutter something about Covariance and Contravariance and wonder off. Usually works in the office environment anyway.
Regards, Rob Philpott.
Rob Philpott wrote:
Covariance and Contravariance
I thought those were added in .net 4.
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In .net, everything is an object. :-D
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Rob Philpott wrote:
Covariance and Contravariance
I thought those were added in .net 4.
You see, I'd have wondered off by the point anyone questions it... This is what I'm thinking of: http://blogs.msdn.com/b/ericlippert/archive/2007/10/19/covariance-and-contravariance-in-c-part-three-member-group-conversion-variance.aspx[^]
Regards, Rob Philpott.
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That's one of those generalizations that I loathe. Yes, structs are objects too. ..but that doesn't make 'em interchangeable :)
I are Troll :suss:
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Eddy Vluggen wrote:
but that doesn't make 'em interchangeable
Yes it does, assuming the container being used to intercahnge them types the variable as object.
J4amieC wrote:
Yes it does, assuming the container being used to intercahnge them types the variable as object.
The keyword here is "assuming", and your assumption is a leaky abstraction :) Reference-types are objects, value-types can be boxed in an reference-type. And no, a namespace isn't an object, it's not even a type. Once you state that everything is an object, people will assume that anything can be used as a base to derive from (since OO is partly about inheriting from existing objects).
I are Troll :suss:
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J4amieC wrote:
Yes it does, assuming the container being used to intercahnge them types the variable as object.
The keyword here is "assuming", and your assumption is a leaky abstraction :) Reference-types are objects, value-types can be boxed in an reference-type. And no, a namespace isn't an object, it's not even a type. Once you state that everything is an object, people will assume that anything can be used as a base to derive from (since OO is partly about inheriting from existing objects).
I are Troll :suss:
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Eddy Vluggen wrote:
Once you state that everything is an object, people will assume that anything can be used as a base to derive from
Any non-sealed Type can be used as a base to derive from. What's your point?
J4amieC wrote:
Any non-sealed Type can be used as a base to derive from.
You can circumvent the impossibility of inheriting a structure by pointing out that it's a sealed class - but that doesn't change the validity of my statement. I took the example of a namespace to prevent the hairsplitting discussion that structs are merely mutilated classes under the hood :)
J4amieC wrote:
What's your point?
That the text "everything is an object" is incorrect. I stated that literally, didn't I? :laugh:
I are Troll :suss:
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J4amieC wrote:
Any non-sealed Type can be used as a base to derive from.
You can circumvent the impossibility of inheriting a structure by pointing out that it's a sealed class - but that doesn't change the validity of my statement. I took the example of a namespace to prevent the hairsplitting discussion that structs are merely mutilated classes under the hood :)
J4amieC wrote:
What's your point?
That the text "everything is an object" is incorrect. I stated that literally, didn't I? :laugh:
I are Troll :suss:
(Whoops, sorry to have started that. :-O )