Re: why no struct inheritance?

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not_a_commie <notacommie@xxxxxxxxx> wrote:
What's the technical reason for not allowing structs to be
hierarchical?

Well, it would be reasonably feasible to allow inheritance so long as
you didn't want polymorphic methods and didn't add any member
variables. You see, if I declare:

struct Point
{
int x;
int y;

// Other operations
}

and then elsewhere in your code:

Point point;

then the "point" variable has room for 8 bytes - 4 for x, 4 for y. If
we were able to do:

Point point = new ExtendedPoint();

then:
a) the runtime couldn't know the actual type of the value, because
there isn't any room for it
b) there wouldn't be room for any extra member variables of
ExtendedPoint


I'm sure there would be ways round this is value type inheritance had
been desired from the start, but the current design doesn't allow it at
all.

As Bob said, extension methods in C# 3 may well help you.

--
Jon Skeet - <skeet@xxxxxxxxx>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too
.

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