Difference between getter and a regular method in Dart

Question

I'm just getting my feet wet with the BLoC architecture of Flutter. Here, I wish to create a Bloc class, which will help me to convert the user input in the form of stream data. To do that task, let's say that first of all I create an instance of Bloc class with the name email and then,

1. make use of snippet 0 & then call email.emailController.sink.add(some_string)
2. or, make use of snippet 1 and then call email.streamEmail(some_string)
3. or, make use of snippet 2 code and then call email.streamEmail(some_string)

to add a string input to the stream

Code snippets:

//Snippet 0 : w/o any `method`
class Bloc{
 final emailController = StreamController<String>();
}

//Snippet 1 : using regular 'method'
class Bloc{
 final emailController = StreamController<String>();
 void streamEmail(String value) => emailController.sink.add(value);
}

//Snippet 2 : using 'get' based 'method'
class Bloc{
 final emailController = StreamController<String>();
 Function(String) get streamEmail => emailController.sink.add;
}

I learned that making use of snippet 1 or 2 is a rather better to approach, in terms of code readability. I know that snippet 1& 2 are just 2 different ways of doing the same thing. However, I'm not clear about the differences that snippet 2 brings in, by making use of the getter method.

From A tour of the Dart language,

Getters and setters are special methods that provide read and write access to an object’s properties.

At the moment, the only thing I understand about getters is that they represent an alternative approach to define methods within a class. So, to be precise my questions are :

1. Does usage of a getter method lead to enhancement or drop in-app. performance?
2. When & why should I be using snippet 2 type class definitions instead of snippet 1?

Answer 1

Does usage of a getter method lead enhancement or drop in app. performance?

No, using getter/setter instead of methods does not impact performance.

When & why should I be using snippet 2 type class definitions instead of snippet 1?

When to use getters/setters is a question about taste and some developers are more likely to use them than others. I guess a general design goal should be that getters/setters acts like normal properties on an object and should therefore not make any additional unknown behavior than getting/setting a property. (e.g. get a property of a objects will end up saving some files to the file system).

In your example I would go with snippet 1 (and maybe with a different name of the method) since your example is not really a good use case of using properties. Snippet 2 seems like a forced clever attempt to make use a getter which ends up being a little weird since the getter ends up returning a Function.

But again, this is a question about taste and I am sure there are some developers which would go with snippet 2.