* Happy New Year(s)!

[ginac.git] / ginac / ptr.h

diff --git a/ginac/ptr.h b/ginac/ptr.h
index 7f305fe1bcc41af012ef84e90380e90006632c20..89bb1d4ae9b62a25ed8e7ad649871991d2d26378 100644 (file)
--- a/ginac/ptr.h
+++ b/ginac/ptr.h
@@ -3,7 +3,7 @@
  *  Reference-counted pointer template. */
 
 /*
- *  GiNaC Copyright (C) 1999-2004 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2007 Johannes Gutenberg University Mainz, Germany
  *
  *  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
@@ -17,7 +17,7 @@
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
 #ifndef __GINAC_PTR_H__
@@ -80,11 +80,14 @@ public:
 
        ptr &operator=(const ptr & other)
        {
-               // NB: must first add reference to "other", since other might be *this.
-               other.p->add_reference();
+               // NB1: Must first add reference to "other", since other might be *this.
+               // NB2: Cache other.p, because if "other" is a subexpression of p,
+               //      deleting p will also invalidate "other".
+               T *otherp = other.p;
+               otherp->add_reference();
                if (p->remove_reference() == 0)
                        delete p;
-               p = other.p;
+               p = otherp;
                return *this;
        }
 
@@ -139,6 +142,7 @@ public:
        inline friend std::ostream & operator<<(std::ostream & os, const ptr<T> & rhs)
        {
                os << rhs.p;
+               return os;
        }
 
 private: