From ab3c697a5e2a963d7f33b7e33f0375a7116fa3fc Mon Sep 17 00:00:00 2001
From: "Paul P.H. Wilson" <paul.wilson@wisc.edu>
Date: Mon, 15 Apr 2024 20:02:58 -0500
Subject: [PATCH] try singleton pattern for unpackaged

---
 src/context.cc | 11 +++++++----
 src/package.cc | 31 +++++++++++++++++++++----------
 src/package.h  | 16 +++++++++-------
 3 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/src/context.cc b/src/context.cc
index 1e56b9af4a..33a6468fa9 100644
--- a/src/context.cc
+++ b/src/context.cc
@@ -85,10 +85,7 @@ Context::Context(Timer* ti, Recorder* rec)
       trans_id_(0),
       si_(0) {
         rng_ = new RandomNumberGenerator();
-        if (packages_.count("unpackaged") == 0) {
-          packages_["unpackaged"] = Package::CreateUnpackaged();
-        }
-}
+      }
 
 Context::~Context() {
   if (solver_ != NULL) {
@@ -207,6 +204,9 @@ Package::Ptr Context::AddPackage(std::string name, double fill_min, double fill_
 }
 
 Package::Ptr Context::GetPackageByName(std::string name) {
+  if (name == Package::unpackaged_name()) {
+    return Package::unpackaged();
+  }
   if (packages_.count(name) == 0) {
     throw KeyError("Invalid package name " + name);
   }
@@ -214,6 +214,9 @@ Package::Ptr Context::GetPackageByName(std::string name) {
 }
 
 Package::Ptr Context::GetPackageById(int id) {
+  if (id == Package::unpackaged_id()) {
+    return Package::unpackaged();
+  }
   if (id < 0) {
     throw ValueError("Invalid package id " + std::to_string(id));
   }
diff --git a/src/package.cc b/src/package.cc
index 784db1c9b4..eff5c6b1d4 100644
--- a/src/package.cc
+++ b/src/package.cc
@@ -17,9 +17,16 @@ Package::Ptr Package::Create(std::string name, double fill_min, double fill_max,
   return p;
 }
 
-Package::Ptr Package::CreateUnpackaged() {
-  Ptr p(new Package(unpackaged_id_, unpackaged_name_));
-  return p;
+// singleton pattern: 
+// if the static member is not yet set, create a new object
+// otherwise return the object that already exists
+Package::Ptr unpackaged() {
+
+  if !unpackaged_ {
+    unpackaged_ = new Package(unpackaged_name_);
+  }
+
+  return unpackaged_;
 }
 
 double Package::GetFillMass(double qty) {
@@ -45,12 +52,16 @@ double Package::GetFillMass(double qty) {
   return fill_mass;
 }
   
-Package::Package() : id_(next_package_id_++), fill_min_(0), fill_max_(std::numeric_limits<double>::max()) {
-  name_ = "unnamed";
-}
-
-Package::Package(std::string name, double fill_min, double fill_max, std::string strategy) : name_(name), id_(next_package_id_++), fill_min_(fill_min), fill_max_(fill_max), strategy_(strategy) {}
-
-Package::Package(int id, std::string name) : id_(id), name_(name), fill_min_(0), fill_max_(std::numeric_limits<double>::max()) {}
+Package::Package(std::string name, double fill_min, double fill_max, std::string strategy) : 
+  name_(name), fill_min_(fill_min), fill_max_(fill_max), strategy_(strategy) {
+    if (name == unpackaged_name_) {
+      if (unpackaged_) {
+        throw ValueError("can't create a package with name " + unpackaged_name_);
+      }
+      id_ = unpackaged_id_;
+    } else {
+      id = next_package_id_++;
+    }
+  }
 
 } // namespace cyclus
diff --git a/src/package.h b/src/package.h
index 1aba7a80d2..53a813321b 100644
--- a/src/package.h
+++ b/src/package.h
@@ -54,16 +54,18 @@ class Package {
     // returns the unpackaged package name
     static std::string unpackaged_name() { return unpackaged_name_; }
 
-  protected:
-    Package();
-    Package(std::string name, double fill_min, double fill_max, std::string strategy);
-    // creates the unpackaged type. Id is always 1.
-    static Package::Ptr CreateUnpackaged();
-    Package(int id, std::string name);
+    // returns the unpackaged singleton object
+    static Ptr unpackaged();
 
   private:
+    Package(std::string name, 
+            double fill_min = 0, 
+            double fill_max = std::numeric_limits<double>::max(), 
+            std::string strategy = "first");
+
     static const int unpackaged_id_ = 1;
-    static const std::string unpackaged_name_ = "unpackaged";
+    static const char* unpackaged_name_ = "unpackaged";
+    static Ptr unpackaged_ = NULL;
     static int next_package_id_;
 
     std::string name_;