The Dink Network

I'd like to propose a new feature for DinkHD, YeOldeDink and any future Dink ports.

A comment by RobJ has given me flashbacks to the days of the browser wars. There are already D-mods that refuse to launch on 'wrong' engine, and I fear that we might be heading to future where we have D-Mods that refuse to launch on anything other than Apache OpenDink™, while everyone has been using LibreDink++ Origin™ for years, and LibreDink++ Origin™ live-patches D-mods based on ther dmod.diz to evade "you are using incompatible port" messages.

I suggest a new function, feature_supported, that checks if a feature exists in current port.
The function would have a signature

bool feature_supported(string name)

.

Here is a piece of code from Hack 'n Slash start.c:

int &chkv = get_version();

//...

if (&chkv <= 108)
{
	&chkv = get_client_fork();
	if (&chkv == 3)
	{
		say_xy("`%THIS ADD-ON REQUIRES DinkHD to play CORRECTLY", -100, 200);
		say_xy("`%YEOLDEDINK may not show `0text `9in correct colours.", -200, 260);
	} else
	{
		say_xy("`% THIS ADD-ON REQUIRES DinkHD to play CORRECTLY", 0, 200);
		wait_for_button();
		kill_game();
		return;
	}
}

What will happen to D-mods like above if we ever get a new Dink port that gives a different value on get_client_fork()? Either we have to hope that the author is still active and updates the D-mod, the port has to check the D-mod against some list of badly behaving D-mods and live-patch matching D-mods, or the D-mods will just fail to run.

With feature_supported(), D-mod authors could do something like this:

if (feature_supported("png images") == 0)
{
	say_xy("`% THIS ADD-ON REQUIRES PNG IMAGE SUPPORT", 0, 200);
	wait_for_button();
	kill_game();
}

if (feature_supported("alpha channels") == 0)
{
	say_xy("`% THIS ADD-ON REQUIRES SUPPORT FOR IMAGES WITH AN ALPHA CHANNEL", 0, 200);
	wait_for_button();
	kill_game();
}

One potential issue with this function is, what happens if the port does not have the feature_supported() function? In this case the game uses last return value of a function, so one should call something that returns 0 immediately before using feature_supported():

//This will make sure that &return == 0 when feature_supported does not exist
math_abs(0);
if (feature_supported("png images") == 0)
{
	//...
}