On Thu, 2004-26-08 at 23:16 -0400, muppet wrote: > On Aug 26, 2004, at 10:56 PM, Ryan McDougall wrote: > GValues are used in code that runs a *lot* (marshaling code for > signals, property mechanism, etc), and need to be fast. allocation on > the stack is far faster than allocation on the heap, and you don't have > to worry about it failing (it happens automatically, even). thus, the > GValue API, like the GtkTreeIter API, is designed to allow you to use > values on the stack. if it's on the stack, you're not going to be > calling free() on it, so you need some way to release any resources it > may contain; hence g_value_unset(), which brackets nicely with > g_value_set_*(). > Don't get me wrong, I see where unset is useful when your programming generically (wrt to types), but I don't know why I can free the pointer inside the value if I want to. > > "unnecessary copies of stack alloc'd GValues"? could you elaborate > here? from what i can see, you always pass GValues by reference, not > by value. why would they be copied? I want to pass a GValue from my API to some user code. How can I do that on the stack? I could ask them to pass in their own GValue and and copy the value to theirs, but I do that in several places, which results in unnecessary copying. > > the only place where i see heap-allocated GValues being necessary is in > something like a collection container, where you're going to hang on to > them for longer than the stack frame will be alive. in that case, > g_new0() by itself is sufficient, but g_value_new() would be nice for > readability. > How did you know I was writing some container code? ;) As usual, Scott, and his quotes about his pregnant wife, rock. ;) Cheers, Ryan _______________________________________________ gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
