+function will fail if you attempt to read in a save file generated by
+a different game from the one configured in this mid-end, even if your
+application is a monolithic one containing all the puzzles. See
+\k{identify-game} for a helper function which will allow you to
+identify a save file before you instantiate your mid-end in the first
+place.
+
+\H{identify-game} \cw{identify_game()}
+
+\c char *identify_game(char **name,
+\c int (*read)(void *ctx, void *buf, int len),
+\c void *rctx);
+
+This function examines a serialised midend stream, of the same kind
+used by \cw{midend_serialise()} and \cw{midend_deserialise()}, and
+returns the \cw{name} field of the game back end from which it was
+saved.
+
+You might want this if your front end was a monolithic one containing
+all the puzzles, and you wanted to be able to load an arbitrary save
+file and automatically switch to the right game. Probably your next
+step would be to iterate through \cw{gamelist} (\k{frontend-backend})
+looking for a game structure whose \cw{name} field matched the
+returned string, and give an error if you didn't find one.
+
+On success, the return value of this function is \cw{NULL}, and the
+game name string is written into \cw{*name}. The caller should free
+that string after using it.
+
+On failure, \cw{*name} is \cw{NULL}, and the return value is an error
+message (which does not need freeing at all).
+
+(This isn't strictly speaking a midend function, since it doesn't
+accept or return a pointer to a midend. You'd probably call it just
+\e{before} deciding what kind of midend you wanted to instantiate.)
+
+\H{midend-request-id-changes} \cw{midend_request_id_changes()}
+
+\c void midend_request_id_changes(midend *me,
+\c void (*notify)(void *), void *ctx);
+
+This function is called by the front end to request notification by
+the mid-end when the current game IDs (either descriptive or
+random-seed) change. This can occur as a result of keypresses ('n' for
+New Game, for example) or when a puzzle supersedes its game
+description (see \k{backend-supersede}). After this function is
+called, any change of the game ids will cause the mid-end to call
+\cw{notify(ctx)} after the change.
+
+This is for use by puzzles which want to present the game description
+to the user constantly (e.g. as an HTML hyperlink) instead of only
+showing it when the user explicitly requests it.
+
+This is a function I anticipate few front ends needing to implement,
+so I make it a callback rather than a static function in order to
+relieve most front ends of the need to provide an empty
+implementation.
~ian / sgt-puzzles.git / blobdiff