C#•2y ago

✅ Cannot convert from anonymous type

I have a method that takes effectively extends OrderBy, and so one of it's paramaters is a keySelector, just like in OrderBy

Func<TElement, TKey> selector

Func<TElement, TKey> selector

In my use case I separated out the intended key to make it read better, so here is it's signature

private static int SelectByDistanceFromEnemy(this (Option<Unit> unit, int index) units)

private static int SelectByDistanceFromEnemy(this (Option<Unit> unit, int index) units)

I'm then using it in this code (lambda to call SelectByDistanceFromEnemy just to try make the error easier to parse)

nits.Select((unit, index) => new { unit, index })
  .RunOrderedDescending(tpl => SelectByDistanceFromEnemy(tpl),
  ...

nits.Select((unit, index) => new { unit, index })
  .RunOrderedDescending(tpl => SelectByDistanceFromEnemy(tpl),
  ...

which gives me this error

cannot convert from '<anonymous type: LanguageExt.Option<Unit> unit, int index>' to '(LanguageExt.Option<Unit> unit, int index)

I don't get why it can't though. The only difference is one is an anonymous type. Anyone know why?

20 Replies

Jayy•2y ago

I mean... That's the difference lol You are trying to pass in a different type as the declared type

LukeJ•2y ago

They're the same tuple, no? (Option<Unit>, int)

Jayy•2y ago

Wait that's an extension method? just switched to my laptop thats an extension lol, call it as an extension an anonymous type is not a tuple no

LukeJ•2y ago

Oh, huh.

MODiX•2y ago

Jayy#6249

REPL Result: Success

(1,2).GetType() == new {foo=1, bar=2}.GetType()

(1,2).GetType() == new {foo=1, bar=2}.GetType()

Result: bool

False

False

Compile: 433.751ms | Execution: 72.370ms | React with ❌ to remove this embed.

Jayy•2y ago

like how would these ever be the same thing? they are totally different

LukeJ•2y ago

Do you have to be like that about it?

Jayy•2y ago

im not being a dick im just trying to make you think

LukeJ•2y ago

If you say so.

Jayy•2y ago

(1,2) has the type ValueTyple<int, int>

LukeJ•2y ago

And the answer of why is because I never real deal with anonymous types and didn't notice this was actually something different.

Jayy•2y ago

new foo=1, bar=2 is an autogenerated compiler type actually hmm how is that represented

MODiX•2y ago

Jayy#6249

REPL Result: Success

new {foo=1, bar=2}.GetType()

new {foo=1, bar=2}.GetType()

Result: RuntimeType

<>f__AnonymousType0#1`2[[System.Int32, System.Private.CoreLib, Version=7.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Int32, System.Private.CoreLib, Version=7.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]], ℛ*d0605842-64ac-48ed-bb56-e8a1083db780#2-0, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null

<>f__AnonymousType0#1`2[[System.Int32, System.Private.CoreLib, Version=7.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e],[System.Int32, System.Private.CoreLib, Version=7.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]], ℛ*d0605842-64ac-48ed-bb56-e8a1083db780#2-0, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null

Compile: 381.479ms | Execution: 62.034ms | React with ❌ to remove this embed.

Jayy•2y ago

f__AnonymousType0#12<int, int> and tuple is ValueTuple<int, int> ValueTuple is also a struct an anon type is a class

LukeJ•2y ago

Ah. So is there an easy conversion here?

Jayy•2y ago

there is no conversion no this might work tho

nits.Select((unit, index) => (unit, index))

nits.Select((unit, index) => (unit, index))

im not actually sure if you can do extensions on tuples like that tho hmm

LukeJ•2y ago

Oh, that totally works. I didn't even realise I was making them as anons and not tuples. Which is weird because I don't seem to be doing that anywhere else in my code... oh well. Learnt something today at least. Thanks.

MODiX•2y ago

Jayy#6249

REPL Result: Success

 public static void Test(this (int, string) foo) => Console.WriteLine(foo.Item2);

var a = (1, "hi");

a.Test();

 public static void Test(this (int, string) foo) => Console.WriteLine(foo.Item2);

var a = (1, "hi");

a.Test();

Console Output

hi

hi

Compile: 586.269ms | Execution: 73.390ms | React with ❌ to remove this embed.

Jayy•2y ago

there we

never actively realized you could do that, filing away for later

Accord•2y ago

Closed!

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✅ Cannot convert from anonymous type