Smart
PointersSmart
PointersIntroduction
+ Common Requirements
+ Exception Safety
+ Exception-specifications
+ History and Acknowledgements
+ References
Smart pointers are objects which store pointers to dynamically allocated (heap) objects. They behave much like built-in C++ pointers except that they automatically delete the object pointed to at the appropriate time. Smart @@ -79,7 +86,7 @@ these idioms.
Note that scoped_ptr requires that T be a complete type at destruction time, but shared_ptr does not.
-Several functions in these smart pointer classes are specified as having "no effect" or "no effect except such-and-such" if an exception is thrown. This means that when an exception is thrown by an object of one of these classes, @@ -90,7 +97,7 @@ the common requirements) is std::bad_alloc, and that is thrown only by functions which are explicitly documented as possibly throwing std::bad_alloc.
-Exception-specifications are not used; see exception-specification rationale.
All the smart pointer templates contain member functions which can never throw @@ -100,7 +107,7 @@
Functions which destroy objects of the pointed to type are prohibited from throwing exceptions by the common requirements.
-January 2002. Peter Dimov reworked all four classes, adding features, fixing bugs, and splitting them into four separate headers, and added weak_ptr. See the compatibility page for a summary of the @@ -114,18 +121,11 @@
September 1999. Luis Coelho provided shared_ptr::swap and shared_array::swap
May 1999. In April and May, 1999, Valentin Bonnard and David Abrahams made a number of suggestions resulting in numerous improvements.
-October 1998. In 1994 Greg Colvin proposed to the C++ Standards Committee - classes named auto_ptr and counted_ptr which were very similar to - what we now call scoped_ptr and shared_ptr. The committee - document was 94-168/N0555, Exception Safe Smart Pointers. In one of the very - few cases where the Library Working Group's recommendations were not followed - by the full committee, counted_ptr was rejected and surprising - transfer-of-ownership semantics were added to auto_ptr.
-Beman Dawes proposed reviving the original semantics under the names safe_ptr - and counted_ptr at an October, 1998, meeting of Per Andersson, Matt +
October 1998. Beman Dawes proposed reviving the original semantics under the names safe_ptr + and counted_ptr, meeting of Per Andersson, Matt Austern, Greg Colvin, Sean Corfield, Pete Becker, Nico Josuttis, Dietmar Kühl, Nathan Myers, Chichiang Wan and Judy Ward. During the discussion, the four - class names were finalized, it was decided that there was no need to exactly + new class names were finalized, it was decided that there was no need to exactly follow the std::auto_ptr interface, and various function signatures and semantics were finalized.
Over the next three months, several implementations were considered for shared_ptr, @@ -154,10 +154,26 @@ experimented with.
But Greg Colvin and Jerry Schwarz argued that "parameterization will discourage users", and in the end we choose to supply only the direct implementation.
+Summer, 1994. Greg Colvin proposed to the C++ Standards Committee + classes named auto_ptr and counted_ptr which were very similar to + what we now call scoped_ptr and shared_ptr. + [Col-94] In one of the very + few cases where the Library Working Group's recommendations were not followed + by the full committee, counted_ptr was rejected and surprising + transfer-of-ownership semantics were added to auto_ptr.
+[Col-94] Gregory Colvin, + + Exception Safe Smart Pointers, C++ committee document 94-168/N0555, + July, 1994.
+[E&D-94] John R. Ellis & David L. Detlefs, + + Safe, Efficient Garbage Collection for C++, Usenix Proceedings, + February, 1994. This paper includes an extensive discussion of weak + pointers and an extensive bibliography.
Revised - 4 February 200215 January 2003
Copyright 1999 Greg Colvin and Beman Dawes. Copyright 2002 Darin Adler. Permission to copy, use, modify, sell and distribute this document is granted @@ -165,4 +181,4 @@ "as is" without express or implied warranty, and with no claim as to its suitability for any purpose.
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