/docs/interop.md: limit parameter count to 8, specify enums

apps/twnlua/bindgen.py

@@ -84,7 +84,7 @@ for procedure, procedure_desc in api["procedures"].items():
             binding += "    %s %s;\n" % (parameter["type"] if not parameter["type"].endswith("*") else 'const ' + parameter["type"], parameter["name"])
             binding += "    lua_getfield(L, 1, \"%s\");\n" % parameter["name"]
 
-            if "default" in parameter and parameter["type"] != "float":
+            if "default" in parameter and not parameter["type"] in ("float", "bool"):
                 binding += "    if (lua_isnoneornil(L, -1))\n"
                 binding += "        %s = %s;\n" % (parameter["name"], default(parameter))
                 binding += "    else\n    "
@@ -141,15 +141,15 @@ for typename, typedesc in used_converters.items():
     converter += "    %s %s;\n" % (typename, typename.lower());
 
     if "fields" in typedesc:
-        for field in typedesc["fields"]:
-            converter += "    lua_getfield(L, -1, \"%s\");\n" % (field["name"]);
+        for idx, field in enumerate(typedesc["fields"]):
+            converter += "    lua_getfield(L, -%i, \"%s\");\n" % (idx + 1, field["name"]);
             if field["type"] == "float":
                 converter += "    %s.%s = (float)lua_tonumber(L, -1);\n" % (typename.lower(), field["name"]);
             elif field["type"] == "uint8_t":
                 converter += "    %s.%s = (uint8_t)lua_tointeger(L, -1);\n" % (typename.lower(), field["name"]);
             else:
                 raise BaseException("Unhandled converter field type '%s'" % (field["type"]))
-            converter += "    lua_pop(L, 1);\n";
+        converter += "    lua_pop(L, %i);\n" % len(typedesc["fields"]);
 
     # TODO: wild idea: use compile time built hash table
     elif "enums" in typedesc:

docs/interop.md

@@ -5,6 +5,7 @@ for that certain considerations are taken:
 * number of public api calls is kept at the minimum
 * procedure parameters can only use basic types, no aggregates, with exception of Vec/Matrix types and alike,
   with no new additions, ever (see [/include/twn_types.h](../include/twn_types.h))
+* enum types are allowed, as they decay to numeric type (but language-specific api can decide to provide simple ways to use them)
 * optionals can be expressed via pointer passage of value primitives, assumed immutable, with the NULL expressing default value
 * no opaque types, only keys if needed
 * pointers to pointers aren't allowed
@@ -15,3 +16,4 @@ for that certain considerations are taken:
 * 32 bit floating point is the only numeric type
 * [/include/twn_api.json](../share/twn_api.json) file is hand-kept with a schema to aid automatic binding generation and tooling
 * parameter names should not collide with keywords of any language that is targetted; if so happens, parameter alias could be added
+* any procedure can't have more than 8 parameters

include/twn_draw.h

@@ -8,6 +8,7 @@
 #include <stdbool.h>
 
 /* pushes a sprite onto the sprite render queue */
+/* TODO: combine flip_x and flip_y into a flip_mask with enum */
 TWN_API void draw_sprite(char const *texture,
                          Rect        rect,
                          Rect const *texture_region,    /* optional, default: NULL */