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diff --git a/src/feature.h b/src/feature.h
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+/*
+ * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_FEATURE_H
+#define INC_FEATURE_H
+
+#include <stdbool.h>
+
+#define _FEATURE_CAT1(a, b) a##b
+#define _FEATURE_CAT(a, b) _FEATURE_CAT1(a, b)
+
+/*
+ * Declares that this translation unit implements a "feature" - a unit of
+ * plugin functionality.
+ *
+ * desc specifies a string to be displayed to the user. Omit this to declare an
+ * internal feature, which won't be advertised, but will be available to other
+ * features.
+ */
+#define FEATURE(... /*desc*/)
+
+/*
+ * Indicates that the specified feature is required for this feature to function.
+ * If that feature fails to initialise, this feature will not be enabled.
+ */
+#define REQUIRE(feature)
+
+/*
+ * Indicates that the specified feature should be initialised before this one,
+ * but is not a hard requirement.
+ *
+ * Presence of a feature can be tested for using has_<featurename>.
+ */
+#define REQUEST(featname) extern bool has_##featname;
+
+/*
+ * Indicates that the specified gamedata entry is required for this feature to
+ * function. If that entry is missing, this feature will not be enabled.
+ *
+ * Note that optional gamedata doesn't need to be specified here as it has no
+ * effect on whether this feature is loaded. It can simply be tested for using
+ * has_<entryname>.
+ */
+#define REQUIRE_GAMEDATA(feature)
+
+/*
+ * Indicates that this feature requires a global variable (such as a factory or
+ * globally-exposed engine interface) to be non-null in order to function. If
+ * the variable has a null/zero value prior to feature initialisation, this
+ * feature will not be enabled.
+ */
+#define REQUIRE_GLOBAL(varname)
+
+/*
+ * Defines the special feature init function which is unique to this translation
+ * unit. This should return true to indicate success, or false to indicate
+ * failure. Features which start to load will cause dependent features not to be
+ * started.
+ *
+ * Features are required to specify this function.
+ */
+#define INIT bool _FEATURE_CAT(_feature_init_, MODULE_NAME)(void) // { code... }
+
+/*
+ * Defines the special, optional feature shutdown function which is unique to
+ * this translation unit. This does not return a value, and may be either
+ * specified once, or left out if no cleanup is required for this feature.
+ */
+#define END void _FEATURE_CAT(_feature_end_, MODULE_NAME)(void) // { code... }
+
+/*
+ * Defines a conditional check to run prior to checking other requirements for
+ * this feature. This can be used to match a certain game type or conditionally
+ * register console variables, and should return true or false to indicate
+ * whether the feature should continue to initialise.
+ */
+#define PREINIT bool _FEATURE_CAT(_feature_preinit_, MODULE_NAME)(void) // {...}
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80