diff options
Diffstat (limited to 'indra/llcommon/llsafehandle.h')
| -rw-r--r-- | indra/llcommon/llsafehandle.h | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/indra/llcommon/llsafehandle.h b/indra/llcommon/llsafehandle.h index af1c26dd4f..74d31297a0 100644 --- a/indra/llcommon/llsafehandle.h +++ b/indra/llcommon/llsafehandle.h @@ -27,6 +27,7 @@ #define LLSAFEHANDLE_H #include "llerror.h" // *TODO: consider eliminating this +#include "llsingleton.h" // Expands LLPointer to return a pointer to a special instance of class Type instead of NULL. // This is useful in instances where operations on NULL pointers are semantically safe and/or @@ -146,15 +147,24 @@ protected: } } - static Type* nonNull(Type* ptr) + // Define an LLSingleton whose sole purpose is to hold a "null instance" + // of the subject Type: the canonical instance to dereference if this + // LLSafeHandle actually holds a null pointer. We use LLSingleton + // specifically so that the "null instance" can be cleaned up at a well- + // defined time, specifically LLSingletonBase::deleteAll(). + // Of course, as with any LLSingleton, the "null instance" is only + // instantiated on demand -- in this case, if you actually try to + // dereference an LLSafeHandle containing null. + class NullInstanceHolder: public LLSingleton<NullInstanceHolder> { - return ptr == NULL ? sNullFunc() : ptr; - } + LLSINGLETON_EMPTY_CTOR(NullInstanceHolder); + public: + Type mNullInstance; + }; - static Type* sNullFunc() + static Type* nonNull(Type* ptr) { - static Type sInstance; - return &sInstance; + return ptr? ptr : &NullInstanceHolder::instance().mNullInstance; } protected: |