Scope[] now returns nil for undefined variables

Given that we have the 'include?' method, this feature
is unnecessary, and it makes sense to convert to more
ruby-like behavior.

Any code that previously checked whether lookupvar
(or the new []) returned :undefined should now check
whether 'scope.include?(var)'.  Thus, you can have
the same behavior, but it takes a bit different code
to get it.

Signed-off-by: Luke Kanies <luke@puppetlabs.com>
Reviewed-by: Nick Lewis <nick@puppetlabs.com>

4 files changed, 17 insertions, 12 deletions

diff --git a/lib/puppet/parser/ast/leaf.rb b/lib/puppet/parser/ast/leaf.rb
index 64a197492..3efb52f63 100644
--- a/lib/puppet/parser/ast/leaf.rb
+++ b/lib/puppet/parser/ast/leaf.rb
@@ -124,10 +124,11 @@ class Puppet::Parser::AST
     # not include syntactical constructs, like '$' and '{}').
     def evaluate(scope)
       parsewrap do
-        if (var = scope[@value, {:file => file, :line => line}]) == :undefined
-          var = :undef
+        if ! scope.include?(@value)
+          :undef
+        else
+          scope[@value, {:file => file, :line => line}]
         end
-        var
       end
     end
 
diff --git a/lib/puppet/parser/resource.rb b/lib/puppet/parser/resource.rb
index 6b072bd90..56887c357 100644
--- a/lib/puppet/parser/resource.rb
+++ b/lib/puppet/parser/resource.rb
@@ -258,7 +258,8 @@ class Puppet::Parser::Resource < Puppet::Resource
 
   def add_backward_compatible_relationship_param(name)
     # Skip metaparams for which we get no value.
-    return unless val = scope[name.to_s] and val != :undefined
+    return unless scope.include?(name.to_s)
+    val = scope[name.to_s]
 
     # The default case: just set the value
     set_parameter(name, val) and return unless @parameters[name]
diff --git a/lib/puppet/parser/scope.rb b/lib/puppet/parser/scope.rb
index 3a87f964b..9d84c7e65 100644
--- a/lib/puppet/parser/scope.rb
+++ b/lib/puppet/parser/scope.rb
@@ -57,7 +57,7 @@ class Puppet::Parser::Scope
       rescue RuntimeError => e
         location = (options[:file] && options[:line]) ? " at #{options[:file]}:#{options[:line]}" : ''
         warning "Could not look up qualified variable '#{name}'; #{e.message}#{location}"
-        :undefined
+        nil
       end
     elsif ephemeral_include?(name) or table.include?(name)
       # We can't use "if table[name]" here because the value might be false
@@ -69,7 +69,7 @@ class Puppet::Parser::Scope
     elsif parent
       parent[name,options.merge(:dynamic => (dynamic || options[:dynamic]))]
     else
-      :undefined
+      nil
     end
   end
 
@@ -92,7 +92,7 @@ class Puppet::Parser::Scope
   end
 
   def include?(name)
-    self[name] != :undefined
+    ! self[name].nil?
   end
 
   # Is the value true?  This allows us to control the definition of truth
@@ -244,7 +244,11 @@ class Puppet::Parser::Scope
   end
 
   def undef_as(x,v)
-    (v == :undefined) ? x : (v == :undef) ? x : v
+    if v.nil? or v == :undef
+      x
+    else
+      v
+    end
   end
 
   def qualified_scope(classname)
diff --git a/lib/puppet/parser/templatewrapper.rb b/lib/puppet/parser/templatewrapper.rb
index 83d18cc3f..9336e704d 100644
--- a/lib/puppet/parser/templatewrapper.rb
+++ b/lib/puppet/parser/templatewrapper.rb
@@ -25,7 +25,7 @@ class Puppet::Parser::TemplateWrapper
 
   # Should return true if a variable is defined, false if it is not
   def has_variable?(name)
-    scope[name.to_s, {:file => file, :line => script_line}] != :undefined
+    scope.include?(name.to_s)
   end
 
   # Allow templates to access the defined classes
@@ -56,9 +56,8 @@ class Puppet::Parser::TemplateWrapper
   # the missing_method definition here until we declare the syntax finally
   # dead.
   def method_missing(name, *args)
-    value = scope[name.to_s, {:file => file,:line => script_line}]
-    if value != :undefined
-      return value
+    if scope.include?(name.to_s)
+      return scope[name.to_s, {:file => file,:line => script_line}]
     else
       # Just throw an error immediately, instead of searching for
       # other missingmethod things or whatever.