Is there a better way to express a parameterless lambda than ()=> ?

Question

The () seems silly. is there a better way?

For example:

ExternalId.IfNotNullDo(()=>ExternalId=ExternalId.Trim());

Answer 1

No, there isn't. Lambda expressions are optimised (in terms of syntax) for the single parameter case.

I know that the C# team feels your pain, and have tried to find an alternative. Whether there ever will be one or not is a different matter.

Answer 2

For a lambda, no: you need () =>

Is it for a delegate or an expression? For delegates, another option is delegate {...}. This may or may not be desirable, depending on the scenario. It is more keys, certainly...

In some cases (not this one) you can use a target method directly - i.e.

ExternalId.IfNotNullDo(SomeMethod);

Answer 3

Dont know exactly what you're doing but as you are doing:

ExternalId.IfNotNullDo(()=>ExternalId=ExternalId.Trim());

can you not restructure it as:

ExternalId.IfNotNullDo(item => item=item.Trim());

-- that would allow you to e.g. convert your nullable to a direct reference to the wrapped item? or:

ExternalId.IfNotNullReplaceWith(item => item.Trim());

Answer 4

Sort of! There is a new idiom in town, that is nice and may help you in some cases. It is not fully what you want, but sometimes I think you will like it.

Since underscore ("_") is a valid C# identifier, it is becoming a common idiom to use it as a parameter name to a lambda in cases where you plan to ignore the parameter anyway. If other coders are aware of the idiom, they will know immediately that the parameter is irrelevant.

For example:

ExternalId.IfNotNullDo( _ => ExternalId=ExternalId.Trim());

Easy to type, conveys your intent, and easier on the eyes as well.

Of course, if you're passing your lambda to something that expects an expression tree, this may not work, because now you're passing a one-parameter lambda instead of a no-parameter lambda.

But for many cases, it is a nice solution. You can find out more about it here.