why "type inference " cann't work

[Nie longhai]

I have a generic method in a class as follow:

T Get<T>(string key)
{
.....
return Convert.ChangeType(v, typeof(T))
}

when I use it in my code:

string ret = MyObject.Get("key");

compile failed , type inference cann't work, why?

thanks for any advice!



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Nie Longhai, Coder ^_*

Shanghai Xomi Instruments Co.,Ltd.

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[Jon Skeet [C# MVP]]

I have a generic method in a class as follow:

T Get<T>(string key)
{
....
return Convert.ChangeType(v, typeof(T))
}

when I use it in my code:

string ret = MyObject.Get("key");

compile failed , type inference cann't work, why?

Type inference is only performed based on parameters, not return
values.

 

[Nie longhai]

Hi, Jon

thank you for your help.
but

Why C# cann't infer type base on return type and cann't overload base on
return type ?

 

[Jon Skeet [C# MVP]]

thank you for your help.
but

Why C# cann't infer type base on return type and cann't overload base on
return type ?

It was a choice made by the language designers to make things less
context-sensitive, so you can always tell from a method call which
overload will be taken etc without the compiler having to take into
account where the result will be used.

It can be a pain at times, but I think overall it adds to readability
of code and simplicity of the language specification.

Jon

 

[cok119]

Hi, Jon

thank you very much.

It was a choice made by the language designers to make things less
context-sensitive, so you can always tell from a method call which
overload will be taken etc without the compiler having to take into
account where the result will be used.

It can be a pain at times, but I think overall it adds to readability
of code and simplicity of the language specification.

Jon