[r] R object identification

I am often ending up with a function producing output for which I don't understand the output data type. I'm expecting a list and it ends up being a list of lists or a data frame or something else. What's a good method or workflow for figuring out the output data type when first using a function?

str(x)

It's all you need to remember for 99% of cases.

attributes(someObject) 

Can also be useful

If I get 'someObject', say via

someObject <- myMagicFunction(...)

then I usually proceed by

class(someObject)
str(someObject)

which can be followed by head(), summary(), print(), ... depending on the class you have.