Add documentation of #dsl_eval_immutable

lib/docile.rb

@@ -3,7 +3,6 @@ require "docile/fallback_context_proxy"
 require "docile/chaining_fallback_context_proxy"
 
 # Docile keeps your Ruby DSLs tame and well-behaved
-# @see http://ms-ati.github.com/docile/
 module Docile
   # Execute a block in the context of an object whose methods represent the
   # commands in a DSL.
@@ -12,8 +11,9 @@ module Docile
   #
   # Use this method to execute an *imperative* DSL, which means that:
   #
-  #   1. each command mutates the state of the DSL context object
-  #   2. the return values of the commands are ignored
+  #   1. Each command mutates the state of the DSL context object
+  #   2. The return value of each command is ignored
+  #   3. The final return value is the original context object
   #
   # @example Use a String as a DSL
   #   Docile.dsl_eval("Hello, world!") do
@@ -42,6 +42,38 @@ module Docile
   end
   module_function :dsl_eval
 
+  # Execute a block in the context of an immutable object whose methods,
+  # and the methods of their return values, represent the commands in a DSL.
+  #
+  # @note Use with a *functional* DSL (commands return successor
+  #       context objects)
+  #
+  # Use this method to execute a *functional* DSL, which means that:
+  #
+  #   1. The original DSL context object is never mutated
+  #   2. Each command returns the next DSL context object
+  #   3. The final return value is the value returned by the last command
+  #
+  # @example Use a String as a DSL
+  #   Docile.dsl_eval_immutable("Hello, world!") do
+  #     reverse
+  #     upcase
+  #   end
+  #   #=> "!DLROW ,OLLEH"
+  #
+  # @example Use a Float as a DSL
+  #   Docile.dsl_eval_immutable(84.5) do
+  #     fdiv(2)
+  #     floor
+  #   end
+  #   #=> 42
+  #
+  # @param dsl   [Object] immutable context object whose methods make up the
+  #                       initial DSL
+  # @param args  [Array]  arguments to be passed to the block
+  # @yield                the block of DSL commands to be executed against the
+  #                         `dsl` context object and successor return values
+  # @return      [Object] the return value of the final command in the block
   def dsl_eval_immutable(dsl, *args, &block)
     exec_in_proxy_context(dsl, ChainingFallbackContextProxy, *args, &block)
   end
@@ -49,6 +81,17 @@ module Docile
 
   private
 
+  # @api private
+  #
+  # Execute a block in the context of an object whose methods represent the
+  # commands in a DSL, using a specific proxy class.
+  #
+  # @param dsl        [Object] context object whose methods make up the
+  #                            (initial) DSL
+  # @param proxy_type [Class]  class to instantiate as the proxy context
+  # @param args       [Array]  arguments to be passed to the block
+  # @yield                     the block of DSL commands to be executed
+  # @return           [Object] the return value of the block
   def exec_in_proxy_context(dsl, proxy_type, *args, &block)
     block_context = eval("self", block.binding)
     proxy_context = proxy_type.new(dsl, proxy_type.new(dsl, block_context))

lib/docile/chaining_fallback_context_proxy.rb

@@ -1,13 +1,18 @@
 require "docile/fallback_context_proxy"
 
 module Docile
-
+  # Operates in the same manner as {FallbackContextProxy}, but replacing
+  # the primary `receiver` object with the result of each proxied method.
+  #
+  # This is useful for implementing DSL evaluation for immutable context
+  # objects.
+  #
+  # @see Docile#dsl_eval_immutable
   class ChainingFallbackContextProxy < FallbackContextProxy
-
+    # Proxy methods as in {FallbackContextProxy#method_missing}, replacing
+    # `receiver` with the returned value.
     def method_missing(method, *args, &block)
       @__receiver__ = super(method, *args, &block)
     end
-
   end
-
 end

lib/docile/fallback_context_proxy.rb

@@ -7,6 +7,10 @@ module Docile
   # Will attempt to forward all method calls first to the primary receiver,
   # and then to the fallback receiver if the primary does not handle that
   # method.
+  #
+  # This is useful for implementing DSL evaluation in the context of an object.
+  #
+  # @see Docile#dsl_eval
   class FallbackContextProxy
     # The set of methods which will **not** be proxied, but instead answered
     # by this object directly.