Wouldn't it be a lot cleaner to make Resource#evaluate idempotent? I would
tend do do something like:
diff --git a/lib/puppet/parser/resource.rb b/lib/puppet/parser/resource.rb
index e34f284..6c217f7 100644
--- a/lib/puppet/parser/resource.rb
+++ b/lib/puppet/parser/resource.rb
@@ -64,14 +64,16 @@ class Puppet::Parser::Resource < Puppet::Resource
# Retrieve the associated definition and evaluate it.
def evaluate
- @evaluated = true
- if klass = resource_type and ! builtin_type?
- finish
- return klass.evaluate_code(self)
+ if evaluated?
+ #nothing to do
elsif builtin?
devfail "Cannot evaluate a builtin type (#{type})"
+ elsif klass = resource_type
+ @evaluated = true
+ finish
+ klass.evaluate_code(self)
else
- self.fail "Cannot find definition #{type}"
+ fail "Cannot find definition #{type}"
end
end
But it could be something as simple as:
diff --git a/lib/puppet/parser/resource.rb b/lib/puppet/parser/resource.rb
index e34f284..c007d4d 100644
--- a/lib/puppet/parser/resource.rb
+++ b/lib/puppet/parser/resource.rb
@@ -64,6 +64,7 @@ class Puppet::Parser::Resource < Puppet::Resource
# Retrieve the associated definition and evaluate it.
def evaluate
+ return if evaluated?
@evaluated = true
if klass = resource_type and ! builtin_type?
finish
My concern is that by handling it out of band we're fighting one set of
non-obvious side effects (evaluating resources can cause others to be
evaluated) by introducing another (fortran like business with flag variables
and nexting in a loop, etc.) and that makes the code more brittle than it
needs to be.
Did you consider this alternative? If so, why was it rejected or if not,
would you consider it?
-- M
-----------------------------------------------------------
The power of accurate observation is
commonly called cynicism by those
who have not got it. ~George Bernard Shaw
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