Allow input of a custom IO for print_tree

[marksiemers]

The default is for print_tree to send output to stdout, I would like the option to send it somewhere else by passing in and IO object to it.

Currently, I'm using this workaround, but I don't really like capturing all of stdout (even if temporarily):

def fetch_tree_text(tree)
  begin
    old_stdout = $stdout
    $stdout = StringIO.new
    tree.print_tree
    $stdout.string
  ensure
    $stdout = old_stdout
  end
end

I would much rather do something like this:

def fetch_tree_text(tree)
  string_io = StringIO.new
  tree.print_tree(io: string_io)
  string_io.string
end

Or maybe even better, have a method that does the same thing, but returns a string, instead sending to an IO.

[net1957]

Hello! print_tree accept a lambda. The default one emit a puts. but you can pass your code.

for example:

def work_on_row(node, prefix)
  # same as default result but on @io
  @io.puts "#{prefix} #{node.name}"
end

@io = StringIO.new
tree.print_tree(,, method(:work_on_row))

#do someting with @io.

Hope this help