[R] listing components of an object

[Nair, Murlidharan T]

Is there a method to list the components of an object, instead of looking at the help for that method?  Let me be more clear with an example

data(iris)
  ## tune `svm' for classification with RBF-kernel (default in svm),
  ## using one split for training/validation set

  obj <- tune(svm, Species~., data = iris,
              ranges = list(gamma = 2^(-1:1), cost = 2^(2:4)),
              tunecontrol = tune.control(sampling = "fix")
             )

  ## alternatively:
  ## obj <- tune.svm(Species~., data = iris, gamma = 2^(-1:1), cost = 2^(2:4))

  summary(obj)
  plot(obj)
---------------------------------
For tune, an object of class tune, including the components:

best.parameters a 1 x k data frame, k number of parameters.
best.performance best achieved performance.
performances if requested, a data frame of all parameter combinations along with the corresponding performance results.
train.ind list of index vectors used for splits into training and validation sets.
best.model if requested, the model trained on the complete training data using the best parameter combination.

I got the above by doing ?tune.

Is there a function that helps be do this?
Thanks ../Murli