1 files changed, 37 insertions, 8 deletions
diff --git a/ext/json/lib/json/add/bigdecimal.rb b/ext/json/lib/json/add/bigdecimal.rb
index c8b4f567cb..b1d0cfa043 100644
--- a/ext/json/lib/json/add/bigdecimal.rb
+++ b/ext/json/lib/json/add/bigdecimal.rb
@@ -2,19 +2,36 @@
 unless defined?(::JSON::JSON_LOADED) and ::JSON::JSON_LOADED
   require 'json'
 end
-defined?(::BigDecimal) or require 'bigdecimal'
+begin
+  require 'bigdecimal'
+rescue LoadError
+end
 
 class BigDecimal
-  # Import a JSON Marshalled object.
-  #
-  # method used for JSON marshalling support.
+
+  # See #as_json.
   def self.json_create(object)
     BigDecimal._load object['b']
   end
 
-  # Marshal the object to JSON.
+  # Methods <tt>BigDecimal#as_json</tt> and +BigDecimal.json_create+ may be used
+  # to serialize and deserialize a \BigDecimal object;
+  # see Marshal[rdoc-ref:Marshal].
+  #
+  # \Method <tt>BigDecimal#as_json</tt> serializes +self+,
+  # returning a 2-element hash representing +self+:
+  #
+  #   require 'json/add/bigdecimal'
+  #   x = BigDecimal(2).as_json             # => {"json_class"=>"BigDecimal", "b"=>"27:0.2e1"}
+  #   y = BigDecimal(2.0, 4).as_json        # => {"json_class"=>"BigDecimal", "b"=>"36:0.2e1"}
+  #   z = BigDecimal(Complex(2, 0)).as_json # => {"json_class"=>"BigDecimal", "b"=>"27:0.2e1"}
+  #
+  # \Method +JSON.create+ deserializes such a hash, returning a \BigDecimal object:
+  #
+  #   BigDecimal.json_create(x) # => 0.2e1
+  #   BigDecimal.json_create(y) # => 0.2e1
+  #   BigDecimal.json_create(z) # => 0.2e1
   #
-  # method used for JSON marshalling support.
   def as_json(*)
     {
       JSON.create_id => self.class.name,
@@ -22,8 +39,20 @@ class BigDecimal
     }
   end
 
-  # return the JSON value
+  # Returns a JSON string representing +self+:
+  #
+  #   require 'json/add/bigdecimal'
+  #   puts BigDecimal(2).to_json
+  #   puts BigDecimal(2.0, 4).to_json
+  #   puts BigDecimal(Complex(2, 0)).to_json
+  #
+  # Output:
+  #
+  #   {"json_class":"BigDecimal","b":"27:0.2e1"}
+  #   {"json_class":"BigDecimal","b":"36:0.2e1"}
+  #   {"json_class":"BigDecimal","b":"27:0.2e1"}
+  #
   def to_json(*args)
     as_json.to_json(*args)
   end
-end
+end if defined?(::BigDecimal)