C#•17mo ago

❔ Type is Typeof Dictionary

I need to test if a System.Type t is a Dictionary of any kind, but when I do this check, it doesn't pass it. How do I test for this?

if (t == typeof(Dictionary<,>))
            {
                Debug.Log("Dictionary");
                return $"{{{ConvertType(t.GenericTypeArguments[0])}:{ConvertType(t.GenericTypeArguments[1])}}}";
            }

if (t == typeof(Dictionary<,>))
            {
                Debug.Log("Dictionary");
                return $"{{{ConvertType(t.GenericTypeArguments[0])}:{ConvertType(t.GenericTypeArguments[1])}}}";
            }

I did a log of the type.tostring after and it said

System.Collections.Generic.Dictionary`2[System.String,System.Object]

System.Collections.Generic.Dictionary`2[System.String,System.Object]

so I believe it is indeed a dictionary. Shouldn't it have passed the check?

12 Replies

MODiX•17mo ago

Ero#1111

REPL Result: Success

Dictionary<string, int> dict = new();

dict.GetType() == typeof(Dictionary<,>)

Dictionary<string, int> dict = new();

dict.GetType() == typeof(Dictionary<,>)

Result: bool

False

False

Compile: 470.383ms | Execution: 30.074ms | React with ❌ to remove this embed.

ero•17mo ago

Weird

Cattywampus•17mo ago

var t = dict.GetType();
bool amIDict = t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Dictionary<,>);

var t = dict.GetType();
bool amIDict = t.IsGenericType && t.GetGenericTypeDefinition() == typeof(Dictionary<,>);

phaseshift•17mo ago

typeof(Dictionary<,>) is not a pattern match type. It is the generic type definition/open generic type. You cannot create something with that type So a real dictionary will never have the same type as an open generic type

LPeter1997•17mo ago

What you were comparing it to is an instance of this generic type. The solution is to ask for the generic definition, like BadaBingBadaBoom showed

Cattywampus•17mo ago

you can as well check the interface if it's IDictionary or not with Type.IsAssignableFrom(Type) depends on what you want

Cattywampus•17mo ago

https://learn.microsoft.com/en-us/dotnet/api/system.type.isassignablefrom?view=net-7.0

Type.IsAssignableFrom(Type) Method (System)

Determines whether an instance of a specified type c can be assigned to a variable of the current type.

skyrbunny•17mo ago

that worked, thank you Can I use this for a Func<> delegate?

Aaron•17mo ago

sure you just need the right amount of commas

MODiX•17mo ago

Windows10CE#8553

REPL Result: Success

var f = (int a, int b, int c) => 4;
f.GetType().GetGenericTypeDefinition() == typeof(Func<,,,>)

var f = (int a, int b, int c) => 4;
f.GetType().GetGenericTypeDefinition() == typeof(Func<,,,>)

Result: bool

True

True

Compile: 533.683ms | Execution: 59.212ms | React with ❌ to remove this embed.

skyrbunny•17mo ago

I eventually figured it out, thanks. boy there's a lot of repetition

Accord•17mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Type is Typeof Dictionary