From b58427e49ffc58f2973615680de0f2d7ef1361c9 Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Sun, 25 Dec 2016 21:46:58 +0100
Subject: [PATCH] Command-Framework: mark anonymous commands

It turns out we *do* support the use of anonymous commands
(while it is not clear yet if we really need this feature).

Basically, client code may either create and register a new
instance from another command used as prototype, by invoking
Command::storeDef(ID). Or, alternatively it may just invoke
newInstance() on the command, which creates a new handle
and a valid new implementation (managed by the handle as
smart-ptr), but never stores this implementation into the
CommandRegistry. In that case, client code may use such a
command just fine, as long as it cares to hold onto that
handle; but it is not possible to retrieve this command
instance later by symbolic ID.

In the light of this (possible) usage pattern, it doesn't
make sense to throw when accessing a command-ID. Rather, we
now return a placeholder-Symbol ("_anonymous_")
---
 .../control/command-impl-clone-builder.hpp    | 17 +++--------
 src/proc/control/command.cpp                  | 30 ++++++++++++-------
 src/proc/control/command.hpp                  |  1 +
 tests/45controller.tests                      |  2 +-
 4 files changed, 26 insertions(+), 24 deletions(-)

diff --git a/src/proc/control/command-impl-clone-builder.hpp b/src/proc/control/command-impl-clone-builder.hpp
index 3f68fdcee..ce18a24a2 100644
--- a/src/proc/control/command-impl-clone-builder.hpp
+++ b/src/proc/control/command-impl-clone-builder.hpp
@@ -29,10 +29,10 @@
  ** command implementation need to be cloned and re-wired with the cloned partners,
  ** which requires re-creating the specifically typed context used at initial setup.
  ** 
- ** Ticket #301 : it may well be that the need for such a facility is a symptom of
- ** misaligned design, but I rather doubt so -- because both the memento holder and
+ ** @todo Ticket #301 : it may well be that the need for such a facility is a symptom
+ ** of misaligned design, but I rather doubt so -- because both the memento holder and
  ** the command closure need a specifically typed context, and there is no reason
- ** for combining them into a single facility. 
+ ** for combining them into a single facility.
  ** 
  ** @see CommandRegistry#createCloneImpl
  ** @see CommandImpl
@@ -46,26 +46,17 @@
 #ifndef CONTROL_COMMAND_IMPL_CLONE_BUILDER_H
 #define CONTROL_COMMAND_IMPL_CLONE_BUILDER_H
 
-//#include "proc/control/command.hpp"
-//#include "proc/control/command-closure.hpp"
 #include "proc/control/command-mutation.hpp"
 #include "lib/typed-allocation-manager.hpp"
 #include "lib/opaque-holder.hpp"
-//#include "lib/bool-checkable.hpp"
 
 #include <boost/noncopyable.hpp>
-//#include <boost/operators.hpp>
-
-//#include <memory>
-//#include <functional>
 
 
 namespace proc {
 namespace control {
   
   using lib::TypedAllocationManager;
-//  using std::function;
-//  using std::shared_ptr;
   using lib::InPlaceBuffer;
   
   
@@ -159,7 +150,7 @@ namespace control {
         {
           REQUIRE (!newContext_->isValid(), "Lifecycle-Error");
           
-          newContext_.create<impl::ClonedContext> (origArgHolder, allocator_); 
+          newContext_.create<impl::ClonedContext> (origArgHolder, allocator_);
         }
       
       
diff --git a/src/proc/control/command.cpp b/src/proc/control/command.cpp
index c4abfcbc6..d0abdfd19 100644
--- a/src/proc/control/command.cpp
+++ b/src/proc/control/command.cpp
@@ -349,14 +349,29 @@ namespace control {
   }
   
   
+  namespace {
+    const Symbol ANONYMOUS_CMD_SYMBOL("_anonymous_");
+  }
+  
   Symbol
   Command::getID()  const
   {
+    ////////////////////////////////////////////////////////////////////TODO do we need no-throw guarantee here?
     Symbol id = CommandRegistry::instance().findDefinition (*this);
-    if (!id)
-      throw error::State("Encountered a NIL command handle while expecting a bound one."
-                        ,error::LUMIERA_ERROR_BOTTOM_VALUE);
-    return id;
+    return id? id
+             : ANONYMOUS_CMD_SYMBOL;
+  }
+  
+  
+  /** @return `true` when this command (front-end) was never registered
+   * with the CommandRegistry; typically this is the case with instances
+   * created from a prototype, when calling Command::newInstance instead
+   * of invoking Command::storeDef(Symbol).
+   */
+  bool
+  Command::isAnonymous()  const
+  {
+    return not CommandRegistry::instance().findDefinition (*this);
   }
   
   
@@ -367,13 +382,8 @@ namespace control {
   Command::operator string() const
   {
     ostringstream repr;
-    repr << "Command";
     ////////////////////////////////////////////////////////////////////TODO do we need no-throw guarantee here?
-    Symbol id = CommandRegistry::instance().findDefinition (*this);
-    if (id)
-      repr << "(\""<<id<<"\") ";
-    else 
-      repr << "(_xxx_) ";
+    repr << "Command(\""<<getID()<<"\") ";
     if (!isValid())
       repr << "NIL";
     else
diff --git a/src/proc/control/command.hpp b/src/proc/control/command.hpp
index caaf63f8f..05c02d6f0 100644
--- a/src/proc/control/command.hpp
+++ b/src/proc/control/command.hpp
@@ -181,6 +181,7 @@ namespace control {
       void duplicate_detected (Symbol)  const;
       
       Symbol getID() const;
+      bool isAnonymous() const;
       
       operator string() const;
       friend bool operator== (Command const&, Command const&);
diff --git a/tests/45controller.tests b/tests/45controller.tests
index f176bbe79..7f6c5ccfb 100644
--- a/tests/45controller.tests
+++ b/tests/45controller.tests
@@ -99,7 +99,7 @@ out: Command\("test.command1.1"\) \{undo\}
 out: Command\("test.command1.2"\) \{undo\}
 out: Command\("test.command1.3"\) \{undo\}
 out: Command\("test.command1.4"\) \{undo\}
-out: Command\(_xxx_\) NIL
+out: Command\("_anonymous_"\) NIL
 out: Command\("test.command1.5"\) \{def\}
 out: Command\("test.command1.5"\) \{exec\}
 out: Command\("test.command1.5"\) \{undo\}