1 files changed, 15 insertions, 1 deletions
diff --git a/lib/irb/frame.rb b/lib/irb/frame.rb
index 8814b47a9d..bcfa3a3140 100644
--- a/lib/irb/frame.rb
+++ b/lib/irb/frame.rb
@@ -17,13 +17,17 @@ module IRB
     def_exception :FrameOverflow, "frame overflow"
     def_exception :FrameUnderflow, "frame underflow"
 
+    # Default number of stack frames
     INIT_STACK_TIMES = 3
+    # Default number of frames offset
     CALL_STACK_OFFSET = 3
 
+    # Creates a new stack frame
     def initialize
       @frames = [TOPLEVEL_BINDING] * INIT_STACK_TIMES
     end
 
+    # Used by Kernel#set_trace_func to register each event in the call stack
     def trace_func(event, file, line, id, binding)
       case event
       when 'call', 'class'
@@ -33,27 +37,37 @@ module IRB
       end
     end
 
+    # Returns the +n+ number of frames on the call stack from the last frame
+    # initialized.
+    #
+    # Raises FrameUnderflow if there are no frames in the given stack range.
     def top(n = 0)
       bind = @frames[-(n + CALL_STACK_OFFSET)]
       Fail FrameUnderflow unless bind
       bind
     end
 
+    # Returns the +n+ number of frames on the call stack from the first frame
+    # initialized.
+    #
+    # Raises FrameOverflow if there are no frames in the given stack range.
     def bottom(n = 0)
       bind = @frames[n]
       Fail FrameOverflow unless bind
       bind
     end
 
-    # singleton functions
+    # Convenience method for Frame#bottom
     def Frame.bottom(n = 0)
       @backtrace.bottom(n)
     end
 
+    # Convenience method for Frame#top
     def Frame.top(n = 0)
       @backtrace.top(n)
     end
 
+    # Returns the binding context of the caller from the last frame initialized
     def Frame.sender
       eval "self", @backtrace.top
     end