is_exactly_a: use typeid() to check the type of expression.

Custom RTTI considered harmful, part 1.

Custom run time type information (RTTI) system implemented in GiNaC have
several serious drawbacks, such as

1. It makes writing GiNaC classes unnecessary cumbersome.
2. It wastes sizeof(void *) bytes per object, for small objects like
   symbol, numeric, etc. this overhead is considerable.

It turns out that GiNaC's RTTI is not any faster than the standard one
(at least on GNU/Linux and Solaris with GNU C++ library and compiler).
So, GiNaC RTTI have no reasons to exit any more.

diff --git a/ginac/basic.h b/ginac/basic.h
index ffc508dbee0dd48ae4b4d6e18b18b96a4f68b1da..304adcfab2ee7c9d757d02feccbbe4415504535e 100644 (file)
--- a/ginac/basic.h
+++ b/ginac/basic.h
@@ -27,6 +27,7 @@
 #include <vector>
 #include <set>
 #include <map>
+#include <typeinfo> // for typeid
 // CINT needs <algorithm> to work properly with <vector>
 #include <algorithm>
 
@@ -306,7 +307,7 @@ inline bool is_a(const basic &obj)
 template <class T>
 inline bool is_exactly_a(const basic & obj)
 {
-       return obj.tinfo() == &T::tinfo_static;
+       return typeid(T) == typeid(obj);
 }
 
 } // namespace GiNaC

diff --git a/ginac/symbol.h b/ginac/symbol.h
index c174ad5f5136b10e83d8dc0dc1cf526b07b142d6..3caa24e45c500c2943a6d8b6be7a57586483ac3f 100644 (file)
--- a/ginac/symbol.h
+++ b/ginac/symbol.h
@@ -24,6 +24,7 @@
 #define __GINAC_SYMBOL_H__
 
 #include <string>
+#include <typeinfo>
 #include "basic.h"
 #include "ex.h"
 #include "ptr.h"
@@ -129,7 +130,7 @@ public:
 /** Specialization of is_exactly_a<realsymbol>(obj) for realsymbol objects. */
 template<> inline bool is_exactly_a<realsymbol>(const basic & obj)
 {
-       if (obj.tinfo() != &symbol::tinfo_static)
+       if (!is_a<symbol>(obj))
                return false;
        unsigned domain = static_cast<const symbol &>(obj).get_domain();
        return domain==domain::real || domain==domain::positive;
@@ -138,7 +139,7 @@ template<> inline bool is_exactly_a<realsymbol>(const basic & obj)
 /** Specialization of is_exactly_a<possymbol>(obj) for possymbol objects. */
 template<> inline bool is_exactly_a<possymbol>(const basic & obj)
 {
-       if (obj.tinfo() != &symbol::tinfo_static)
+       if (!is_a<symbol>(obj))
                return false;
        unsigned domain = static_cast<const symbol &>(obj).get_domain();
        return domain == domain::positive;