How do you determine the data type of calling object in Groovy?

Question

When I'm calling a function in Groovy, how do I determine the class of the caller?

For example, I want to know what the class of foo is, inside the printFoo() function:

foo.printFoo()

def printFoo() {
  print(this.class)
}

And this should print out the class of foo

Not sure about Groovy specific, but Java provides a way which is specified in [this question](http://stackoverflow.com/questions/421280/how-do-i-find-the-caller-of-a-method-using-stacktrace-or-reflection) — christopher, Mar 31 '15 at 16:53
@christopher That technique is going to be problematic, particularly with Groovy's dynamic dispatch because there are going to be potentially a lot of frames between the caller and the destination. — Jeff Scott Brown, Apr 01 '15 at 12:16

sebnukem · Answer 1 · 2017-06-16T14:15:16.433

3

I don't know of any Groovy-specific way, but you can get the class name with object.getClass().name. Is that what you are looking for?

If you want to check if an object implements a particular interface or extends a particular class (e.g. Date) use:

object instanceof Date

or to check if the class of an object is exactly a particular class (not a subclass of it), use:

object.getClass() == Date

There's also the in operator: object in Date

edited Jun 16 '17 at 14:15

answered Mar 31 '15 at 17:28

sebnukem

8,143
6
38
48

My question is more related to the class of the object that called the function, so if foo calls printFoo(), how would you access the foo's class, inside printFoo()? – reectrix Mar 31 '15 at 17:50
Then your example should work. What's the error or problem with it? – sebnukem Mar 31 '15 at 17:55
Ah, okay. I wasn't sure if it was proper syntax/form. Thanks! – reectrix Mar 31 '15 at 18:22
2

You should call `getClass()` instead of `class`. – sebnukem Mar 31 '15 at 19:10

score 1 · Accepted Answer · answered Apr 01 '15 at 12:14

The language and the runtime don't provide a reliable mechanism to do what you are asking about. You can do some pokey jiggery inspecting stack frames but that is really detailed low level stuff and won't really be reliable for a number of reasons. The short answer is, the language just doesn't support it.

How do you determine the data type of calling object in Groovy?

2 Answers2