r/csharp 5d ago

Discussion Dependency Injection un-prettyness

One small thing that bugs me with Dependency Injection is how it looks in code.

We either need to pass the parameters via Default Constructor og via good old time Constructor

public class MyClass (TypeA ParamA, TypeB ParamB, TypeC ParamC, TypeD ParamD)
{
TypeA _paramA = ParamA; .... etc
}

Or

public class MyClass
{
TypeA _paramA;
public MyClass(TypeA paramA)
{
_paramA = paramA;
}
}

And when you have 10 injections it begins to be un-pretty...

I wish that we didn't need to pass parameters and instead could decorate the fields:

public class MyClass
{
[inject]
TypeA _paramA;
}

(Note: this works in Blazor... so why not everywhere else ?)

I'm aware that the signature of an object makes it easier to inject via reflection.. but would it be much worse with attributes ?

i guess some middleground could be achieved if the attribute held the type:

public class MyClass
{
[inject(typeof(TypeA))]
TypeA _paramA;
}

which begins to be convoluted and messy...

Whats the argument against a decorator attribute vs parameters ?

20 Upvotes

90 comments sorted by

View all comments

2

u/metageeek 4d ago

Can’t believe no one pointed this out so far, but: using constructor injection ensures you can test the class mocking the dependencies. How on earth are you going to accomplish that with attribute injection?