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Any? to Dictionary Cast and retrieving value


Any? to Dictionary Cast and retrieving value

By : user2951221
Date : November 18 2020, 01:01 AM
hop of those help? println(paramValue as Dictionary) won't work because dictionary is type-safe.
You could use:
code :
println(paramValue as [String : Int])


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Why can't I cast a dictionary of one value type to dictionary of another value type when the value types can be cast fro

Why can't I cast a dictionary of one value type to dictionary of another value type when the value types can be cast fro


By : Osmar Melo Jr
Date : March 29 2020, 07:55 AM
around this issue
Is this a flaw in the Dictionary casting mechanism, or in my thinking that this should be allowed?
code :
Dictionary<int, List<string>> castMeDict = 
    new Dictionary<int, List<string>>();

Dictionary<int, IEnumerable<string>> getFromDict = 
    (Dictionary<int, IEnumerable<string>>)castMeDict;

castMeDict[123] = new List<string>();
IEnumerable<string> strings = getFromDict[123]; // No problem!
getFromDict[123] = new string[] { "hello" }; // Big problem!
Why can't Dictionary<T1, List<T2>> be cast to Dictionary<T1, IEnumerable<T2>>?

Why can't Dictionary<T1, List<T2>> be cast to Dictionary<T1, IEnumerable<T2>>?


By : Milton Perrin
Date : March 29 2020, 07:55 AM
may help you . I'm wondering why I can't just cast (I have a vague idea this might have something to do with that co/contravariance stuff?), and am I forced to copy the elements of the first dictionary to a new one in order to get the type I want? , You cannot do this because they aren't the same type. Consider:
code :
        var x = new Dictionary<string, List<int>>();

        // won't compile, but assume it could...
        Dictionary<string, IEnumerable<int>> xPrime = x;

        // uh oh, would allow us to legally add array of int!
        xPrime["Hi"] = new int[13];
Dictionary<int, Dog> 
Dictionary<int, Animal>
How can I cast a subset of a dictionary to a type derived from Dictionary<>

How can I cast a subset of a dictionary to a type derived from Dictionary<>


By : Z.F. Su
Date : March 29 2020, 07:55 AM
I hope this helps you . You get an invalid cast exception because the result of ToDictionary is not MyDict. In order to fix this problem, add a constructor to MyDict that takes an IDictionary, and return the result of calling that constructor from your GetSubSet method:
code :
public class MyDict : Dictionary<string, A> {
    public MyDict() {
        // Perform the default initialization here
        ...
    }
    public MyDict(IDictionary<string,A> dict): base(dict) {
        // Initialize with data from the dict if necessary
        ...
    }
}
...
public MyDict GetSubSet(int testVal) {
    var ret = dict.Where(e => e.Value.aValue == testVal).
                   ToDictionary(k => k.Key, k => k.Value);
    return new MyDict(ret);
}
How to specify generic cast for Dictionary values while retrieving

How to specify generic cast for Dictionary values while retrieving


By : Marty Punsch
Date : March 29 2020, 07:55 AM
this one helps. You need to tell the compiler and the users of your APIs that TResult will be a name of a reference type, not a name of a value type:
code :
public static TResult GetValue<TKey, TValue, TResult>(this Dictionary<TKey, TValue> dictionary, TKey key)
    where TResult : class {
    ...
}
public static TResult? GetNullableValue<TKey, TValue, TResult>(this Dictionary<TKey, TValue> dictionary, TKey key)
    where TResult : struct {
    ...
}
How do you cast a dictionary<int, child> to dictionary<int, parent>?

How do you cast a dictionary<int, child> to dictionary<int, parent>?


By : jwgilbertCO
Date : March 29 2020, 07:55 AM
I wish this helpful for you Let's say I have: , Maybe something like this?
code :
void IterateTable<T>(Dictionary<int, T> dictionary)
    where T : Animal
{
    foreach(var entry in dictionary)
        entry.Value.Attack();
}
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