Man hooks (concepts)
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Revision as of 17:00, 11 June 2007
Description
To allow a greater flexibility of the muds, the gamedrivers since 3.2.1 moved several once hardcoded 'underground' activities from the driver into the mudlib. This includes for example the differences between compat and native mode.
The hooks are set with the privileged efun set_driver_hook(). Some of the hooks are mandatory, some not. Most hooks accept unbound lambda closures as values, some also lfun closures or even strings.
The hooks are identified by an ordinal number, for which symbolic names are defined in /sys/driverhooks.h.
- H_MOVE_OBJECT0, H_MOVE_OBJECT1
Mandatory hooks to implement the efun void move_object(). Hook setting must be an unbound lambda closure:
void <closure>(object item, object dest)
Upon call, the hook has to perform the move itself (by using set_environment()) and all depending actions (like the calls to init() to add actions).
The difference lies in the binding of the set hook prior to the call: the H_MOVE_OBJECT0 closure is bound to the current object, the H_MOVE_OBJECT1 to 'item'. If both hooks are set, H_MOVE_OBJECT0 is ignored.
- H_LOAD_UIDS, H_CLONE_UIDS
Mandatory hooks to determine the uid and euid of loaded or cloned objects. Hook settings can be any closure:
mixed <load_uids closure> (string objectname) mixed <clone_uids closure>(object blueprint, string objectname)
When an object is newly loaded, the H_LOAD_UIDS hook is called with the object name as argument. When an object is cloned, the H_CLONE_UIDS hook is called with the blueprint object as first and the clone's designated name as second argument. In both cases the new object already exists, but has 0 uids.
For the result, the following possibilities exist (<num> is a non-zero number, <no-string> is anything but a string):
"<uid>" -> uid = "<uid>", euid = "<uid>"
({ "<uid>", "<euid>" }) -> uid = "<uid>", euid = "<euid>"
({ "<uid>", <no-string> }) -> uid = "<uid>", euid = 0
If strict-euids is not active, the following results are possible, too:
<num> -> uid = 0, euid = 0
({ <num>, "<euid>" }) -> uid = 0, euid = "<euid>"
({ <num>, <no-string> }) -> uid = 0, euid = 0
- H_CREATE_SUPER, H_CREATE_OB, H_CREATE_CLONE
Optional hooks to initialize an object after creation. Hook setting can be unbound lambda closures, or the name of the function to call in the object.
H_CREATE_SUPER is called for blueprints implicitely loaded by inheritance, H_CREATE_OB for explicitely loaded blueprints/objects, and H_CREATE_CLONE for cloned objects.
If the hook is a closure expecting an argument, it is bound to the current object and called as
int <closure> (object obj_to_init)
If the hook as a closure without arguments, it is bound to the object to be initalized and called as
int <closure> ( void )
If the result of the call is a non-zero number, it is used as the interval to wait before the first reset(), else the default interval computed from TIME_TO_RESET is used.
If the hook is defined as the name of an lfun (static or public) in the object, it is called in the object as
void <name>(0)
and any result is ignored. In this call the previous_object() is the object initiating the load.
- H_RESET
Optional hook to reset an object. Hook setting can be unbound lambda closures, or the name of the function to call in the object.
This hook is called to reset the object after a certain time since its creation/last reset.
If the hook is a closure, it is bound to the object to be reset and called with no argument:
void|int <closure> ( void )
If the result of the call is a positive number, it is used as the interval to wait before the next reset(). If the result is 0, the default interval computed from TIME_TO_RESET is used. If the result is a negative number, the object will not be reset again, unless directed otherwise by set_next_reset().
If the hook is defined as the name of an lfun (static or public) in the object, it is called in the object as
void <name>(1)
and any result is ignored. In this call the previous_object() is the object initiating the reset. If the function does not exist, the object won't be reset again.
- H_CLEAN_UP
Optional hook to clean up an object. Hook setting can be any closure, or the name of the function to call in the object.
This hook is called for an object if it hasn't been used for at least TIME_TO_CLEAN_UP seconds, to give it the opportunity to self destruct.
If the hook is a closure, it is called as
int <closure>(int ref, object ob)
with the object's refcount as first argument, and object itself as second. Lambda closures are also bound to the object prior to the call.
If the hook is the name of an lfun, it is called in the object with its refcount as argument:
void|int <name>(int ref)
In both calls, the refcount is constructed as:
ref = 0: the object is a clone, or a blueprint with
replaced program.
ref = 1: the object is a swapped or unused blueprint.
ref > 1: the object is a used blueprint with <ref> references.
The cleanup method has the possibility to destruct the object. To survive this time, but try again some time later, the call has to result in a non-zero value.
If the hook specifies a non-existing lfun, or if the call returns 0, no further attempt to clean up this object will be done.
- H_COMMAND
Optional hook to parse and execute commands. If this hook is used, it bypasses the normal command parsing done by the driver (including the MODIFY_COMMAND and NOTIFY_FAIL hooks).
The hook is called with two parameters: the command received from the living (interactive user or NPC), and the living object (the 'command giver') itself. The hook has to return non-0 if the command was found and executed, and 0 otherwise.
At the time the hook is called, query_command() returns the command string and this_player() returns the living object. query_verb() and query_notify_fail() return 0.
If the hook is a string, it is the name of an lfun in the command giver:
int <name>(string command, object command_giver)
If the hook is a closure, it is called as:
int <closure>(string command, object command_giver)
Lambda-closures are additionally bound to the command_giver.
- H_MODIFY_COMMAND
Optional hook to modify commands (both entered or given by a call to command()) before the parser sees them (this includes special commands like 'status').
Hook setting can be any closure, the name of the function to call in the object, or a mapping.
For interactives this hook is used only if the interactive object has no command modifier already set by the efun set_modify_command().
If the hook is a closure, it is called as
int|string <closure>(string cmd, object player)
with the entered command as first, and the command giving player as second argument.
If the hook is a string, it is used as the name of an lfun in the command giving player, which is called as
int|string <name>(string cmd)
If the hook is a mapping, it is queried with the given command as index, and the data retrieved is used (defaults to 0 if no data is stored for a given command). If an entry is a closure, it is called as
int|string <closure>(string cmd, object player)
and the result from the call is used as 'the' result.
The result is treated equal in all three cases. If the result is a string, it is the new command to execute instead of the given one. Note that it is not possible to make several commands from one this way! If the result is a non-zero number, the given command is to be ignored. In case of the closure/lfun setting this may mean that the closure/lfun already executed it. If the result is 0, the originally given command is to be used.
It is possible for the hook to change the command giver (this_player()) for the execution of the command. This means that even though the commands are execute for the original commandgiver, this_player() will return the changed commandgiver.
- H_MODIFY_COMMAND_FNAME
Mandatory hook specifying the name of the 'modify_command' function to call for newly entered commands as result of a set_modify_command().
Hook setting must be a string.
If set_modify_command() is used for an interactive user, all newly entered commands are first passed to the function named by this hook.
The function is called as
int|string <name>(string cmd)
If the result is a string, it is the new command to execute instead of the given one. Note that it is not possible to make several commands from one this way! If the result is a non-zero number, the given command is to be ignored. In case of the closure/lfun setting this may mean that the closure/lfun already executed it. If the result is 0, the originally given command is to be used.
It is possible for the hook to change the command giver (this_player()) for the execution of the command. This means that even though the commands are execute for the original commandgiver, this_player() will return the changed commandgiver.
- H_NOTIFY_FAIL
Mandatory hook to issue the default message if an entered command couldn't be parsed and no notify_fail() command is in effect. Hook setting can be a any closure, or a string.
If set to a string, it is the message returned to the player. If set to a closure, it is called as
string <closure>(string entered_command, object cmd_giver)
and the result is used as failure message. Lambda closures are bound to this_player() prior to execution.
<cmd_giver> is the object which received the command in the first place. It is usually identical with this_player(), unless the H_MODIFY_COMMAND hook changed it.
- H_SEND_NOTIFY_FAIL
Optional hook to send the notify fail message, regardless of how it was determined, to the player. If the hook is not set, the message is delivered using tell_object() internally. Hook setting can be a string or a closure.
If the hook is a string, it is the name of a (possibly static) function to call in the current command giver. If the hook is a closure, it is the function to be called. Lambda closures are bound to the current command giver first.
The function is called as
void <function>(string msg, object msgobj, object orig_cmd_giver)
<msg> is the notify fail message to be delivered. <msgobj> is the object which set the message. It is 0 for the default message. <orig_cmd_giver> is the object for which the original command was first received. It is usually identical with the current command giver this_player().
- H_NO_IPC_SLOT
Optional hook specifying the message given to logins rejected due to space limitations (MAX_PLAYER). Hook setting has to be string. If set to 0, the default message "Lpmud is full. Come back later." is issued.
- H_INCLUDE_DIRS
Semi-mandatory hook specifying the directories where <>-type include files are searched (this includes ""-includes not found as specified). Hook setting may be any closure or a string array. If not set, only ""-type includes may be used in LPC programs.
The hook is called only if a call to master::include_file() does not return a usable filename.
If the hook setting is a string array, it has to contain the path names of those directories where <>-type includes are to be searched. The directories are searched in the order they appear in the array. The directory name and the name of the actual include file are concatenated, therefore the directory names have to end in '/'. Leading slashes may be omitted.
If the setting is a closure, it is called as
string <closure>(string include_name, string current_file)
with the name of the desired include file as first, and the name of the compiled LPC file as second argument. Result has to be the complete path name of the include file to use (leading slashes may be omitted). If the closure is a lambda closure, it is bound to this_object() prior to execution.
- H_AUTO_INCLUDE
Optional hook specifying a string to be included before the source of every compiled LPC object. Hook setting can be a string or a closure.
If the setting is a string, it will be automatically included before the source of every compiled LPC object.
If the setting is a closure, it is called as
string <closure>(string base_file, string current_file
, int sys_include)
for every file opened by the compiler. <base_file> will be the filename of the compiled object, <current_file> the name of a file included directly or indirectly by the <base_file>. When the <base_file> itself is opened, <current_file> will be 0. For an included file, <sys_include> will be TRUE if it is a <>-type include.
If the result is a string, it will be included before the actual text of the file.
- H_TELNET_NEG
Optional hook to specifiy how to perform a single telnet negotiation. Hook setting may be any closure or a string. If not set, most telnet options are rejected (read: only a very minimal negotiation takes place).
The hook is called whenever the driver receives a demand for option negotiation for:
SB: Suboption negotiation TELOPT_LINEMODE: linemode TELOPT_NAWS: window size TELOPT_TTYPE: terminal type TELOPT_TM: timing mark TELOPT_NEWENV: remote environment variables TELOPT_ENVIRON: remote environment variables TELOPT_XDISPLOC: remote X display address TELOPT_TSPEED: terminal speed TELOPT_BINARY: binary data, needed for non-ASCII charsets TELOPT_EOR: TinyFugue prompt marker (together with EOR)
TELOPT_COMPRESS: Mud Compression Protocol TELOPT_COMPRESS2: Mud Compression Protocol TELOPT_MSP: Mud Sound Protocol TELOPT_MXP: Mud Extension Protocol
The hook has then to perform the negotiation using the efun binary_message().
Alternatively, if H_NOECHO is set, this hook is called for all telnet data received.
If the setting is a string, it used as name of an lfun to call in this_player():
void|mixed <name>(int action, int option [, int * opts ] )
Similar, if the setting is a closure, it is called as:
void|mixed <closure>(int action, int option [, int * opts ] )
with unbound lambda-closures being bound to this_player() prior to execution.
The hook is called for a 'DO/DONT/WILL/WONT <opt>' with the action (DO/DONT/...) as the first, and <opt> as the second argument.
If the driver receives the sequence
IAC SB <opt> <opts>...
followed by IAC SB/SE, the hook is called with 'SB' as first argument, <opt> as second, and <opts> as an array of integers as third argument.
- H_NOECHO
Optional hook to specifiy how to perform the telnet actions to switch the echo mode (used for e.g. password input_to()s). Hook setting may be any closure or a string. If not set, a default handling is performed.
If the setting is a string, it used as name of an lfun to call in the intercative <user>:
void <name>(int flag, object user, int no_telnet)
where <flag> is the echo-flag passed to the input_to() statement. Similar, if the setting is a closure, it is called as:
void <closure>(int flag, object user, int no_telnet)
with unbound lambda-closures being bound to this_player() prior to execution.
When set, the hook is called whenever the driver needs to change the echo mode, thus you can negotiate about things that are coupled with it, like LINEMODE or character-at-a-time.
<local> is a boolean flag: it is TRUE when input_to() was called with the INPUT_NO_TELNET flag.
IMPORTANT: If this hook is used, the control of all telnet negotiation is transferred to the mudlib: all incoming negotiations are passed to H_TELNET_NEG, and the sending of no-echo negotiations is handled by this hook.
- H_ERQ_STOP
Optional hook to notify the mudlib about the termination of the erq demon. Hook setting may be any closure.
The closure is called without arguments:
void <closure>()
and may do whatever it likes to clean-up after the erq.
History
H_NOTIFY_FAIL recevied the new 'command_giver' argument in 3.2.7. The hooks concept was introduced in 3.2.1 The hook for moving was introduced in 3.2.1@1 The hook for clean up was introduced in 3.2.1@34 The hook for modifying commands was introduced in 3.2.1@51, the evaluation of mapping as hooks was extended in 3.2.1@54. The lfun called as result of set_modify_command() was 'hooked' in 3.2.1@109. The hooks for notify_fail and full muds were introduced in 3.2.1@55. The hook for include dirs was introduced in 3.2.1@57. The hook for telnet negotiation was introduced in 3.2.1@60. The hooks for no-echo negotiation and erq-lossage notification were introduced in 3.2.1@85. H_COMMAND was introduced in 3.2.7. H_SEND_NOTIFY_FAIL and H_AUTO_INCLUDE were introduced in 3.2.9. LDMud 3.2.10 allowed static functions to be specified by name for H_RESET and H_CREATE_* LDMud 3.2.11 added the <no_telnet> argument to H_NOECHO.
