From 89a67770e66d11740948e90a41db6cee0482cf8e Mon Sep 17 00:00:00 2001
From: Patrick J Cherry <patrick@bytemark.co.uk>
Date: Wed, 13 Apr 2011 17:03:16 +0100
Subject: new version.

---
 lib/object_builder.rb | 113 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 113 insertions(+)
 create mode 100644 lib/object_builder.rb

(limited to 'lib/object_builder.rb')

diff --git a/lib/object_builder.rb b/lib/object_builder.rb
new file mode 100644
index 0000000..7cb808c
--- /dev/null
+++ b/lib/object_builder.rb
@@ -0,0 +1,113 @@
+# ObjectBuilder is a class to help you build Ruby-based configuration syntaxes.
+# You can use it to make "builder" classes to help build particular types
+# of objects, typically translating simple command-based syntax to creating
+# classes and setting attributes.  e.g. here is a description of a day at 
+# the zoo:
+#   
+#   person "Alice"
+#   person "Matthew"
+#
+#   zoo("London") {
+#     enclosure("Butterfly House") {
+#
+#       has_roof
+#       allow_visitors
+#       
+#       animals("moth", 10) {
+#         wings 2
+#         legs 2
+#       }
+#
+#       animals("butterfly", 200) {
+#         wings 2
+#         legs 2
+#       }
+#     }
+#
+#     enclosure("Aquarium") {
+#       no_roof
+#
+#       animal("killer whale") {
+#         called "Shamu"
+#         wings 0
+#         legs 0
+#         tail
+#       }
+#     }
+#   }
+#
+# Here is the basic builder class for a Zoo...
+#
+# TODO: finish this convoluted example, if it kills me
+#
+class ObjectBuilder
+  class BuildException < Exception; end 
+  
+  attr_reader :result
+  
+  def initialize(context, *args)
+    @context = context
+    builder_setup(*args)
+  end
+  
+  def anonymous_name
+    @@sequence ||= 0 # not inherited, don't want it to be
+    @@sequence  += 1
+    "anon.#{Time.now.to_i}.#{@@sequence}"
+  end
+  
+  class << self
+  
+    def is_builder(word, clazz)
+      define_method(word.to_sym) do |*args, &block|
+        builder = clazz.new(*([@context] + args))
+        builder.instance_eval(&block) if block
+        ["created_#{word}", "created"].each do |created_method|
+          created_method = created_method.to_sym
+          if respond_to?(created_method)
+            __send__(created_method, builder.result)
+            break
+          end
+        end
+      end
+    end
+    
+    # FIXME: implement is_builder_deferred to create object at end of block?
+    
+    def is_block_attribute(word)
+      define_method(word.to_sym) do |*args, &block|
+        @result.__send__("#{word}=".to_sym, block)
+      end
+    end
+    
+    def is_attribute(word)
+      define_method(word.to_sym) do |*args, &block|
+        @result.__send__("#{word}=".to_sym, args[0])
+      end
+    end
+    
+    def is_flag_attribute(word)
+      define_method(word.to_sym) do |*args, &block|
+        @result.__send__("#{word}=".to_sym, true)
+      end
+    end
+  
+    def load(file)
+      builder = self.new
+      builder.instance_eval(File.read(file), file)
+      builder.result
+    end
+    
+    def inherited(*args)
+      initialize_class
+    end
+    
+    def initialize_class
+      @words = {}
+    end
+  end
+  
+  initialize_class
+end
+
+
-- 
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