lang: funcs: Rename things for consistency

Also fix a few copy-pasta issues in the documentation.

lang/funcs/facts/core/answer_fact.go

@@ -0,0 +1,76 @@
+// Mgmt
+// Copyright (C) 2013-2018+ James Shubin and the project contributors
+// Written by James Shubin <james@shubin.ca> and the project contributors
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package core // TODO: should this be in its own individual package?
+
+import (
+	"github.com/purpleidea/mgmt/lang/funcs/facts"
+	"github.com/purpleidea/mgmt/lang/types"
+)
+
+func init() {
+	facts.Register("answer", func() facts.Fact { return &AnswerFact{} }) // must register the fact and name
+}
+
+// Answer is the Answer to Life, the Universe and Everything.
+const Answer = 42
+
+// AnswerFact returns the Answer to Life, the Universe and Everything.
+type AnswerFact struct {
+	init      *facts.Init
+	closeChan chan struct{}
+}
+
+// Validate makes sure we've built our struct properly. It is usually unused for
+// normal facts that users can use directly.
+//func (obj *AnswerFact) Validate() error {
+//	return nil
+//}
+
+// Info returns some static info about itself.
+func (obj *AnswerFact) Info() *facts.Info {
+	return &facts.Info{
+		Output: types.NewType("int"),
+	}
+}
+
+// Init runs some startup code for this fact.
+func (obj *AnswerFact) Init(init *facts.Init) error {
+	obj.init = init
+	obj.closeChan = make(chan struct{})
+	return nil
+}
+
+// Stream returns the changing values that this fact has over time. In this
+// case, it returns a single value and then exits, since this is a static fact.
+func (obj *AnswerFact) Stream() error {
+	select {
+	case obj.init.Output <- &types.IntValue{
+		V: Answer,
+	}:
+	case <-obj.closeChan:
+		return nil
+	}
+	close(obj.init.Output) // signal that we're done sending
+	return nil
+}
+
+// Close runs some shutdown code for this fact and turns off the stream.
+func (obj *AnswerFact) Close() error {
+	close(obj.closeChan)
+	return nil
+}