Re: Threadsafe singletons
Matthias Hofmann wrote:
"kanze" <email@example.com> schrieb im Newsbeitrag
What could happen? The only thing I can imagine is using
the char pointer to modify the string literal. This can be
fixed by using a pointer to a const char.
char doh = "How long will I exist?" ;
Singleton::GetInstance().SetName( doh ) ;
I wouldn't like to use the singleton after a call to muckItUp.
I see. Would it make a difference if doh' were a pointer to a
char rather than an array, as follows?
char* doh = "Am I located on the stack?";
Obviously. The problem is one of object lifetime; using a char
pointer, instead of std::string, only works if the object
lifetime of the char const it points to is static (or strictly
speaking, at least until the next call to SetName. Anytime you
pass the address of a string literal, this condition is met.
David's example is probably more realistic of what will happen
in practice. The user will create the string in an std::string,
and then use c_str() to pass it to SetName.
James Kanze GABI Software
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