Dictionary append question

[csharpula csharp]

Hello,
I was wondering if there is a way in c# to append two Dictionaries of
the same type:

Dictionary<stri ng,objectdic1 and Dictionary<stri ng,objectdic2 into
one new Dictionary<stri ng,object?

(Is there any kind of AddRange such as exisits in generic list)?

Thank you very much!



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[Ignacio Machin ( .NET/ C# MVP )]

Re: Dictionary append question

On May 19, 8:43 am, csharpula csharp <csharp...@yaho o.comwrote:

Hello,
I was wondering if there is a way in c# to append two Dictionaries of
the same type:
>
Dictionary<stri ng,objectdic1  and Dictionary<stri ng,objectdic2 into
one new Dictionary<stri ng,object?
>
(Is there any kind of AddRange such as exisits in generic list)?

It's not that simple, what happens if both dics share a common key?

You could simply create one such a method though. You could even use a
delegate to defer the decision of what to do with the shared keys

[Marc Gravell]

Re: Dictionary append question

You could simply create one such a method though.

And in C#3, an extension method (perhaps on IDictionary<TKe y,TValue>)
would be trivial. But as Ignacio rightly says - you need to decide how
to treat conflicts. Personally I'd probably just let it blow up by
default...

Marc

[csharpula csharp]

Re: Dictionary append question

Could you please explain how can I create a general method for
Dictionary (tkey,tvalue) merge?



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[Marc Gravell]

Re: Dictionary append question

Something like below; this specific example uses C# 3, but you can do
similar with C# 2 - you just lose the ability to use
left.AddRange(r ight) - you have to do SomeClass.AddRa nge(left,right)
[perhaps renaming the method].

Marc

using System;
using System.Collecti ons.Generic;
using System.Xml.Linq ;
static class Program
{
static void Main()
{
// dictionary
var left = new Dictionary<int, string>();
left.Add(1, "Fred");
left.Add(2, "Barney");

var right = new Dictionary<int, string>();
right.Add(3, "Wilma");
right.Add(4, "Betty");

left.AddRange(r ight);
}
}

public static class DictionaryExt
{
public static void AddRange<TKey, TValue>(
this IDictionary<TKe y, TValuedestinati on,
IDictionary<TKe y, TValuevalues)
{
if (destination == null) throw new
ArgumentNullExc eption("destina tion");
if (values == null) throw new ArgumentNullExc eption("values" );

foreach (var pair in values)
{
destination.Add (pair);
}
}
public static void Merge<TKey, TValue>(
this IDictionary<TKe y, TValuedestinati on,
IDictionary<TKe y, TValuevalues)
{
if (destination == null) throw new
ArgumentNullExc eption("destina tion");
if (values == null) throw new ArgumentNullExc eption("values" );

foreach (var pair in values)
{
destination[pair.Key] = pair.Value;
}
}
}