fixup safebool syntax in halo::handle

There was a subtle flaw introduced by using safebool in halo_record,
but defining the handle as a pointer to this -- the pointer also
is castable to bool so it makes mistakes very easy. We replace the
safe bool stuff with a function "valid" of halo_record, and fixup
the places that were supposed to be using this test.

Also move the NO_HALO variable back to the header.

fixes up commit 82c6b98

src/halo.cpp

@@ -28,8 +28,6 @@
 namespace halo
 {
 
-const int NO_HALO = 0;
-
 class halo_impl
 {
 
@@ -522,8 +520,8 @@ halo_record::halo_record(int id, const boost::shared_ptr<halo_impl> & my_manager
 
 halo_record::~halo_record()
 {
-	if (id_ == NO_HALO) return;
-	if (my_manager_.expired()) return;
+	if (!valid()) return;
+
 	boost::shared_ptr<halo_impl> man = my_manager_.lock();
 
 	if (man) {

src/halo.hpp

@@ -28,6 +28,7 @@ class display;
 namespace halo
 {
 
+
 class halo_impl;
 
 class halo_record;
@@ -36,6 +37,8 @@ typedef boost::shared_ptr<halo_record> handle;
 
 enum ORIENTATION { NORMAL, HREVERSE, VREVERSE, HVREVERSE };
 
+const int NO_HALO = 0;
+
 class manager
 {
 public:
@@ -82,33 +85,15 @@ class halo_record : public boost::noncopyable
 	halo_record(int id, const boost::shared_ptr<halo_impl> & my_manager);
 	~halo_record();
 
+	bool valid() const {
+		return id_ != NO_HALO && !my_manager_.expired();
+	}
 
 	friend class manager;
 private:
 	int id_;
 	boost::weak_ptr<halo_impl> my_manager_;
 
-//Begin safe_bool impl
-
-#ifndef HAVE_CXX11
-	struct safe_bool_impl { void nonnull() {} };
-	/**
-	 * Used as t he return type of the conversion operator for boolean contexts.
-	 * Needed, since the compiler would otherwise consider the following
-	 * conversion (C legacy): cfg["abc"] -> "abc"[bool(cfg)] -> 'b'
-	 */
-	typedef void (safe_bool_impl::*safe_bool)();
-#endif
-
-public:
-#ifdef HAVE_CXX11
-	explicit operator bool() const
-	{ return id_ != 0 && !my_manager_.expired(); }
-#else
-	operator safe_bool() const
-	{ return (id_ != 0 && !my_manager_.expired()) ? &safe_bool_impl::nonnull : NULL; }
-#endif
-
 };
 
 } // end namespace halo

src/unit_drawer.cpp

@@ -161,13 +161,14 @@ void unit_drawer::redraw_unit (const unit & u) const
 	const int x = static_cast<int>(adjusted_params.offset * xdst + (1.0-adjusted_params.offset) * xsrc) + hex_size_by_2;
 	const int y = static_cast<int>(adjusted_params.offset * ydst + (1.0-adjusted_params.offset) * ysrc) + hex_size_by_2;
 
-	if(!ac.unit_halo_ && !u.image_halo().empty()) {
+	bool has_halo = ac.unit_halo_ && ac.unit_halo_->valid();
+	if(!has_halo && !u.image_halo().empty()) {
 		ac.unit_halo_ = halo_man.add(0, 0, u.image_halo()+u.TC_image_mods(), map_location(-1, -1));
 	}
-	if(ac.unit_halo_ && u.image_halo().empty()) {
+	if(has_halo && u.image_halo().empty()) {
 		halo_man.remove(ac.unit_halo_);
 		ac.unit_halo_ = halo::handle(); //halo::NO_HALO;
-	} else if(ac.unit_halo_) {
+	} else if(has_halo) {
 		halo_man.set_location(ac.unit_halo_, x, y - height_adjust);
 	}