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  • Can an object oriented program be seen as a Finite State Machine?

    - by Peretz
    This might be a philosophical/fundamental question, but I just want to clarify it. In my understanding a Finite State Machine is a way of modeling a system in which the system's output will not only depend on the current inputs, but also the current state of the system. Additionally, as the name suggests it, a finite state machine can be segmented in a finite N number of states with its respective state and behavior. If this is correct, shouldn't every single object with data and function members be a state in our object oriented model, making any object oriented design a finite state machine? If that is not the interpretation of a FSM in object design, what exactly people mean when they implement a FSM in software? am I missing something? Thanks

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  • Prove this Tautology (No Truth Tables)

    - by FSM
    This is for homework for my Discrete Math class. I understand how to prove tautologies with a truth table. I'm having trouble figuring out how to do it without though. I found this example in our text, but the solution is not provided. I was hoping someone could answer it as best they could so I could apply it to my other questions. Thanks! ! = not/invert ^ = and V = or - = if then [!P ^ (P V Q) ] - Q I also am completely lost for this question (I fear I'll be tested on something of this difficulty) [ (P - Q) ^ (Q - R) ] - (P - R) Thanks for the help all!

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  • python socket.recv/sendall call blocking

    - by fsm
    Hi everyone. This post is incorrectly tagged 'send' since I cannot create new tags. I have a very basic question about this simple echo server. Here are some code snippets. client while True: data = raw_input("Enter data: ") mySock.sendall(data) echoedData = mySock.recv(1024) if not echoedData: break print echoedData server while True: print "Waiting for connection" (clientSock, address) = serverSock.accept() print "Entering read loop" while True: print "Waiting for data" data = clientSock.recv(1024) if not data: break clientSock.send(data) clientSock.close() Now this works alright, except when the client sends an empty string (by hitting the return key in response to "enter data: "), in which case I see some deadlock-ish behavior. Now, what exactly happens when the user presses return on the client side? I can only imagine that the sendall call blocks waiting for some data to be added to the send buffer, causing the recv call to block in turn. What's going on here? Thanks for reading!

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  • strange behavior in python

    - by fsm
    The tags might not be accurate since I am not sure where the problem is. I have a module where I am trying to read some data from a socket, and write the results into a file (append) It looks something like this, (only relevant parts included) if __name__ == "__main__": <some init code> for line in file: t = Thread(target=foo, args=(line,)) t.start() while nThreads > 0: time.sleep(1) Here are the other modules, def foo(text): global countLock, nThreads countLock.acquire() nThreads += 1 countLock.release() """connect to socket, send data, read response""" writeResults(text, result) countLock.acquire() nThreads -= 1 countLock.release() def writeResults(text, result): """acquire file lock""" """append to file""" """release file lock""" Now here's the problem. Initially, I had a typo in the function 'foo', where I was passing the variable 'line' to writeResults instead of 'text'. 'line' is not defined in the function foo, it's defined in the main block, so I should have seen an error, but instead, it worked fine, except that the data was appended to the file multiple times, instead of being written just once, which is the required behavior, which I got when I fixed the typo. My question is, 1) Why didn't I get an error? 2) Why was the writeResults function being called multiple times?

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  • Is this a valid quine?

    - by fsm
    def start(fileName): fileReader = open(fileName) for row in fileReader: print row, if __name__ == "__main__": import sys if len(sys.argv) <= 1: print "usage quine /path/to/file" sys.exit(-1) fileName = sys.argv[0] start(fileName) python quine.py foo

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  • How to handle very frequent updates to a Lucene index

    - by fsm
    I am trying to prototype an indexing/search application which uses very volatile indexing data sources (forums, social networks etc), here are some of the performance requirements, Very fast turn-around time (by this I mean that any new data (such as a new message on a forum) should be available in the search results very soon (less than a minute)) I need to discard old documents on a fairly regular basis to ensure that the search results are not dated. Last but not least, the search application needs to be responsive. (latency on the order of 100 milliseconds, and should support at least 10 qps) All of the requirements I have currently can be met w/o using Lucene (and that would let me satisfy all 1,2 and 3), but I am anticipating other requirements in the future (like search relevance etc) which Lucene makes easier to implement. However, since Lucene is designed for use cases far more complex than the one I'm currently working on, I'm having a hard time satisfying my performance requirements. Here are some questions, a. I read that the optimize() method in the IndexWriter class is expensive, and should not be used by applications that do frequent updates, what are the alternatives? b. In order to do incremental updates, I need to keep committing new data, and also keep refreshing the index reader to make sure it has the new data available. These are going to affect 1 and 3 above. Should I try duplicate indices? What are some common approaches to solving this problem? c. I know that Lucene provides a delete method, which lets you delete all documents that match a certain query, in my case, I need to delete all documents which are older than a certain age, now one option is to add a date field to every document and use that to delete documents later. Is it possible to do range queries on document ids (I can create my own id field since I think that the one created by lucene keeps changing) to delete documents? Is it any faster than comparing dates represented as strings? I know these are very open questions, so I am not looking for a detailed answer, I will try to treat all of your answers as suggestions and use them to inform my design. Thanks! Please let me know if you need any other information.

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  • Code Golf: Finite-state machine!

    - by Adam Matan
    Finite state machine A deterministic finite state machine is a simple computation model, widely used as an introduction to automata theory in basic CS courses. It is a simple model, equivalent to regular expression, which determines of a certain input string is Accepted or Rejected. Leaving some formalities aside, A run of a finite state machine is composed of: alphabet, a set of characters. states, usually visualized as circles. One of the states must be the start state. Some of the states might be accepting, usually visualized as double circles. transitions, usually visualized as directed arches between states, are directed links between states associated with an alphabet letter. input string, a list of alphabet characters. A run on the machine begins at the starting state. Each letter of the input string is read; If there is a transition between the current state and another state which corresponds to the letter, the current state is changed to the new state. After the last letter was read, if the current state is an accepting state, the input string is accepted. If the last state was not an accepting state, or a letter had no corresponding arch from a state during the run, the input string is rejected. Note: This short descruption is far from being a full, formal definition of a FSM; Wikipedia's fine article is a great introduction to the subject. Example For example, the following machine tells if a binary number, read from left to right, has an even number of 0s: The alphabet is the set {0,1}. The states are S1 and S2. The transitions are (S1, 0) -> S2, (S1, 1) -> S1, (S2, 0) -> S1 and (S2, 1) -> S2. The input string is any binary number, including an empty string. The rules: Implement a FSM in a language of your choice. Input The FSM should accept the following input: <States> List of state, separated by space mark. The first state in the list is the start state. Accepting states begin with a capital letter. <transitions> One or more lines. Each line is a three-tuple: origin state, letter, destination state) <input word> Zero or more characters, followed by a newline. For example, the aforementioned machine with 1001010 as an input string, would be written as: S1 s2 S1 0 s2 S1 1 S1 s2 0 S1 s2 1 s2 1001010 Output The FSM's run, written as <State> <letter> -> <state>, followed by the final state. The output for the example input would be: S1 1 -> S1 S1 0 -> s2 s2 0 -> S1 S1 1 -> S1 S1 0 -> s2 s2 1 -> s2 s2 0 -> S1 ACCEPT For the empty input '': S1 ACCEPT For 101: S1 1 -> S1 S1 0 -> s2 s2 1 -> s2 REJECT For '10X': S1 1 -> S1 S1 0 -> s2 s2 X REJECT Prize A nice bounty will be given to the most elegant and short solution. Reference implementation A reference Python implementation will be published soon.

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  • AI for a mixed Turn Based + Real Time battle system - Something "Gambit like" the right approach?

    - by Jason L.
    This is maybe a question that's been asked 100 times 1,000 different ways. I apologize for that :) I'm in the process of building the AI for a game I'm working on. The game is a turn based one, in the vein of Final Fantasy but also has a set of things that happen in real time (reactions). I've experimented with FSM, HFSMs, and Behavior Trees. None of them felt "right" to me and all felt either too limiting or too generic / big. The idea I'm toying with now is something like a "Rules engine" that could be likened to the Gambit system from Final Fantasy 12. I would have a set of predefined personalities. Each of these personalities would have a set of conditions it would check on each event (Turn start, time to react, etc). These conditions would be priority ordered, and the first one that returns true would be the action I take. These conditions can also point to a "choice" action, which is just an action that will make a choice based on some Utility function. Sort of a mix of FSM/HFSM and a Utility Function approach. So, a "gambit" with the personality of "Healer" may look something like this: (ON) Ally HP = 0% - Choose "Relife" spell (ON) Ally HP < 50% - Choose Heal spell (ON) Self HP < 65% - Choose Heal spell (ON) Ally Debuff - Choose Debuff Removal spell (ON) Ally Lost Buff - Choose Buff spell Likewise, a "gambit" with the personality of "Agressor" may look like this: (ON) Foe HP < 10% - Choose Attack skill (ON) Foe any - Choose target - Choose Attack skill (ON) Self Lost Buff - Choose Buff spell (ON) Foe HP = 0% - Taunt the player What I like about this approach is it makes sense in my head. It also would be extremely easy to build an "AI Editor" with an approach like this. What I'm worried about is.. would it be too limiting? Would it maybe get too complicated? Does anyone have any experience with AIs in Turn Based games that could maybe provide me some insight into this approach.. or suggest a different approach? Many thanks in advance!!!

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  • Writing a Master's Thesis on evaluating visual scripting systems

    - by user1107412
    I am thinking to write my Master's thesis around theorizing, and then implementing a PlayMaker or Kismet-like (building game logic by visually arranging FSMs) tool in Unity. The only thing I am still concerned about is the actual research question that I should pose. I was kinda hoping that the more experienced game designers out there might know. Update: What about reducing the use of visual programming to graphically designing FSM-Action-Transition flows, which can then be attached to game entities (very much like http://playmaker.com does it)?

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  • parsing the output of the 'w' command?

    - by Blackbinary
    I'm writing a program which requires knowledge of the current load on the system, and the activity of any users (it's a load balancer). This is a university assignment, and I am required to use the w command. I'm having a hard time parsing this command because it is very verbose. Any suggestions on what I can do would be appreciated. This is a small part of the program, and I am free to use whatever method i like. The most condensed version of w which still has the information I require is `w -u -s -f' which produces this: 10:13:43 up 9:57, 2 users, load average: 0.00, 0.00, 0.00 USER TTY IDLE WHAT fsm tty7 22:44m x-session-manager fsm pts/0 0.00s w -u -s -f So out of that, I am interested in the first number after load average and the smallest idle time (so i will need to parse them all). My background process will call w, so the fact that w is the lowest idle time will not matter (all i will see is the tty time). Do you have any ideas? Thanks (I am allowed to use alternative unix commands, like grep, if that helps).

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  • Snort network instruction Mac OS X

    - by Rasatavohary
    I'm trying to learn network intrusion detection. When I try to launch Snort, in IDS mode, I get this message (I'm running Mac OS X): Initializing Network Interface en1 ERROR: OpenPcap() FSM compilation failed: syntax error PCAP command: snort Fatal Error, Quitting.. How can I fix this problem?

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  • float addition 2.5 + 2.5 = 4.0? RPN

    - by AJ Clou
    The code below is my subprogram to do reverse polish notation calculations... basically +, -, *, and /. Everything works in the program except when I try to add 2.5 and 2.5 the program gives me 4.0... I think I have an idea why, but I'm not sure how to fix it... Right now I am reading all the numbers and operators in from command line as required by this assignment, then taking that string and using sscanf to get the numbers out of it... I am thinking that somehow the array that contains the three characters '2', '.', and '5', is not being totally converted to a float... instead i think just the '2' is. Could someone please take a look at my code and either confirm or deny this, and possibly tell me how to fix it so that i get the proper answer? Thank you in advance for any help! float fsm (char mystring[]) { int i = -1, j, k = 0, state = 0; float num1, num2, ans; char temp[10]; c_stack top; c_init_stack (&top); while (1) { switch (state) { case 0: i++; if ((mystring[i]) == ' ') { state = 0; } else if ((isdigit (mystring[i])) || (mystring[i] == '.')) { state = 1; } else if ((mystring[i]) == '\0') { state = 3; } else { state = 4; } break; case 1: temp[k] = mystring[i]; k++; i++; if ((isdigit (mystring[i])) || (mystring[i] == '.')) { state = 1; } else { state = 2; } break; case 2: temp[k] = '\0'; sscanf (temp, "%f", &num1); c_push (&top, num1); i--; k = 0; state = 0; break; case 3: ans = c_pop (&top); if (c_is_empty (top)) return ans; else { printf ("There are still items on the stack\n"); exit (0); case 4: num2 = c_pop (&top); num1 = c_pop (&top); if (mystring[i] == '+'){ ans = num1 + num2; return ans; } else if (mystring[i] == '-'){ ans = num1 - num2; return ans; } else if (mystring[i] == '*'){ ans = num1 * num2; return ans; } else if (mystring[i] == '/'){ if (num2){ ans = num1 / num2; return ans; } else{ printf ("Error: cannot divide by 0\n"); exit (0); } } c_push (&top, ans); state = 0; break; } } } } Here is my main program: #include <stdio.h> #include <stdlib.h> #include "boolean.h" #include "c_stack.h" #include <string.h> int main(int argc, char *argv[]) { char mystring[100]; int i; sscanf("", "%s", mystring); for (i=1; i<argc; i++){ strcat(mystring, argv[i]); strcat(mystring, " "); } printf("%.2f\n", fsm(mystring)); } and here is the header file with prototypes and the definition for c_stack: #include "boolean.h" #ifndef CSTACK_H #define CSTACK_H typedef struct c_stacknode{ char data; struct c_stacknode *next; } *c_stack; #endif void c_init_stack(c_stack *); boolean c_is_full(void); boolean c_is_empty(c_stack); void c_push(c_stack *,char); char c_pop(c_stack *); void print_c_stack(c_stack); boolean is_open(char); boolean is_brother(char, char); float fsm(char[]);

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  • newly added files don't sync down

    - by poolie
    I added some files into my Ubuntu One/My Files folder on my desktop machine. I can see them in the U1 web ui. My laptop is connected to the same U1 account, and in the Ubuntu One preference pane I can see it's connected to the account. However, my new files never download. In syncdaemon.log I can see it checking a bunch of other existing files, and then the file ends with many repetitions of 2011-01-04 11:05:42,277 - ubuntuone.SyncDaemon.Main - NOTE - ---- MARK (state: <State: 'READY' (queues WORKING_ON_METADATA connection 'Not User With Network')>; queues: metadata: 1; content: 0; hash: 0, fsm-cache: hit=5086 miss=69) ---- I do have a working network connection. What do I do now?

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  • what knowledge would I need to make a good simulation games

    - by Skeith
    I have an idea for a game like theme park but don't know how simulation games are made. I am not some noob on his first game so I appreciated constructive answers instead of "its hard, don't do it". What I want is to know how simulation game mechanics are put together. I figure it would be heaver on the AI than normal games and not knowing much about AI would like to know some programming techniques I should look into for this style game. specific techniques please not just a book on ai. what sort of architecture would be used? I guess it would have some sort of probability engine with pre designed events that are triggered based on the AI state. Would it use a FSM or be purely event driven ? Any information on how a sims game functions would be cool.

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  • Extracting the source code of a facebook page with JavaScript

    - by Hafizi Vilie
    If I write code in the JavaScript console of Chrome, I can retrieve the whole HTML source code by entering: var a = document.body.InnerHTML; alert(a); For fb_dtsg on Facebook, I can easily extract it by writing: var fb_dtsg = document.getElementsByName('fb_dtsg')[0].value; Now, I am trying to extract the code "h=AfJSxEzzdTSrz-pS" from the Facebook Page. The h value is especially useful for Facebook reporting. How can I get the h value for reporting? I don't know what the h value is; the h value is totally different when you communicate with different users. Without that h correct value, you can not report. Actually, the h value is AfXXXXXXXXXXX (11 character values after 'Af'), that is what I know. Do you have any ideas for getting the value or any function to generate on Facebook page. The Facebook Source snippet is below, you can view source on facebook profile, and search h=Af, you will get the value: <code class="hidden_elem" id="ukftg4w44"> <!-- <div class="mtm mlm"> ... .... <span class="itemLabel fsm">Unfriend...</span></a></li> <li class="uiMenuItem" data-label="Report/Block..."> <a class="itemAnchor" role="menuitem" tabindex="-1" href="/ajax/report/social.php?content_type=0&amp;cid=1352686914&amp;rid=1352686914&amp;ref=http%3A%2F%2Fwww.facebook.com%2 F%3Fq&amp;h=AfjSxEzzdTSrz-pS&amp;from_gear=timeline" rel="dialog"> <span class="itemLabel fsm">Report/Block...</span></a></li></ul></div> ... .... </div> --> </code> Please guide me. How can extract the value exactly? I tried with following code, but the comment block prevent me to extract the code. How can extract the value which is inside comment block? var a = document.getElementsByClassName('hidden_elem')[3].innerHTML;alert(a);

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  • Determining percentage of students between certain grades

    - by dunc
    I have an Excel spreadsheet with the following data: #-----------------------------------------------------------------------------------------------------------------------------------# # Student # KS2 Grade # Target # Expected 1 # Expected 2 # Expected 3 # FSM Status # Gifted & Talented # #-----------------------------------------------------------------------------------------------------------------------------------# # User 1 # 4 # 6 # 7 # 5 # 6 # Y # N # # User 2 # 3 # 5 # 5 # 4 # 4 # N # N # # User 3 # 5 # 6 # 6 # 6 # 7 # N # N # # User 4 # 4 # 6 # 5 # 6 # 6 # N # Y # # User 5 # 5 # 7 # 7 # 6 # 7 # N # N # # User 6 # 3 # 4 # 4 # 4 # 4 # N # N # # User 7 # 3 # 4 # 5 # 3 # 4 # Y # Y # #-----------------------------------------------------------------------------------------------------------------------------------# What I'd like to do is determine the percentage of students with certain levels, i.e. a range of levels. For instance, in the data above, I'd like to determine the % of all students that have a Target level of 5 - 7. I'd then like to also expand the formula to specify % of Gifted & Talented students with a Target level of 5 - 7. Is this possible in Excel? If so, where do I start?

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  • Maintaining State in Mud Engine

    - by Johnathon Sullinger
    I am currently working on a Mud Engine and have started implementing my state engine. One of the things that has me troubled is maintaining different states at once. For instance, lets say that the user has started a tutorial, which requires specific input. If the user types "help" I want to switch in to a help state, so they can get the help they need, then return them to the original state once exiting the help. my state system uses a State Manager to manage the state per user: public class StateManager { /// <summary> /// Gets the current state. /// </summary> public IState CurrentState { get; private set; } /// <summary> /// Gets the states available for use. /// </summary> /// <value> public List<IState> States { get; private set; } /// <summary> /// Gets the commands available. /// </summary> public List<ICommand> Commands { get; private set; } /// <summary> /// Gets the mob that this manager controls the state of. /// </summary> public IMob Mob { get; private set; } public void Initialize(IMob mob, IState initialState = null) { this.Mob = mob; if (initialState != null) { this.SwitchState(initialState); } } /// <summary> /// Performs the command. /// </summary> /// <param name="message">The message.</param> public void PerformCommand(IMessage message) { if (this.CurrentState != null) { ICommand command = this.CurrentState.GetCommand(message); if (command is NoOpCommand) { // NoOperation commands indicate that the current state is not finished yet. this.CurrentState.Render(this.Mob); } else if (command != null) { command.Execute(this.Mob); } else if (command == null) { new InvalidCommand().Execute(this.Mob); } } } /// <summary> /// Switches the state. /// </summary> /// <param name="state">The state.</param> public void SwitchState(IState state) { if (this.CurrentState != null) { this.CurrentState.Cleanup(); } this.CurrentState = state; if (state != null) { this.CurrentState.Render(this.Mob); } } } Each of the different states that the user can be in, is a Type implementing IState. public interface IState { /// <summary> /// Renders the current state to the players terminal. /// </summary> /// <param name="player">The player to render to</param> void Render(IMob mob); /// <summary> /// Gets the Command that the player entered and preps it for execution. /// </summary> /// <returns></returns> ICommand GetCommand(IMessage command); /// <summary> /// Cleanups this instance during a state change. /// </summary> void Cleanup(); } Example state: public class ConnectState : IState { /// <summary> /// The connected player /// </summary> private IMob connectedPlayer; public void Render(IMob mob) { if (!(mob is IPlayer)) { throw new NullReferenceException("ConnectState can only be used with a player object implementing IPlayer"); } //Store a reference for the GetCommand() method to use. this.connectedPlayer = mob as IPlayer; var server = mob.Game as IServer; var game = mob.Game as IGame; // It is not guaranteed that mob.Game will implement IServer. We are only guaranteed that it will implement IGame. if (server == null) { throw new NullReferenceException("LoginState can only be set to a player object that is part of a server."); } //Output the game information mob.Send(new InformationalMessage(game.Name)); mob.Send(new InformationalMessage(game.Description)); mob.Send(new InformationalMessage(string.Empty)); //blank line //Output the server MOTD information mob.Send(new InformationalMessage(string.Join("\n", server.MessageOfTheDay))); mob.Send(new InformationalMessage(string.Empty)); //blank line mob.StateManager.SwitchState(new LoginState()); } /// <summary> /// Gets the command. /// </summary> /// <param name="message">The message.</param> /// <returns>Returns no operation required.</returns> public Commands.ICommand GetCommand(IMessage message) { return new NoOpCommand(); } /// <summary> /// Cleanups this instance during a state change. /// </summary> public void Cleanup() { // We have nothing to clean up. return; } } With the way that I have my FSM set up at the moment, the user can only ever have one state at a time. I read a few different posts on here about state management but nothing regarding keeping a stack history. I thought about using a Stack collection, and just pushing new states on to the stack then popping them off as the user moves out from one. It seems like it would work, but I'm not sure if it is the best approach to take. I'm looking for recommendations on this. I'm currently swapping state from within the individual states themselves as well which I'm on the fence about if it makes sense to do there or not. The user enters a command, the StateManager passes the command to the current State and lets it determine if it needs it (like passing in a password after entering a user name), if the state doesn't need any further commands, it returns null. If it does need to continue doing work, it returns a No Operation to let the state manager know that the state still requires further input from the user. If null is returned, the state manager will then go find the appropriate state for the command entered by the user. Example state requiring additional input from the user public class LoginState : IState { /// <summary> /// The connected player /// </summary> private IPlayer connectedPlayer; private enum CurrentState { FetchUserName, FetchPassword, InvalidUser, } private CurrentState currentState; /// <summary> /// Renders the current state to the players terminal. /// </summary> /// <param name="mob"></param> /// <exception cref="System.NullReferenceException"> /// ConnectState can only be used with a player object implementing IPlayer /// or /// LoginState can only be set to a player object that is part of a server. /// </exception> public void Render(IMob mob) { if (!(mob is IPlayer)) { throw new NullReferenceException("ConnectState can only be used with a player object implementing IPlayer"); } //Store a reference for the GetCommand() method to use. this.connectedPlayer = mob as IPlayer; var server = mob.Game as IServer; // Register to receive new input from the user. mob.ReceivedMessage += connectedPlayer_ReceivedMessage; if (server == null) { throw new NullReferenceException("LoginState can only be set to a player object that is part of a server."); } this.currentState = CurrentState.FetchUserName; switch (this.currentState) { case CurrentState.FetchUserName: mob.Send(new InputMessage("Please enter your user name")); break; case CurrentState.FetchPassword: mob.Send(new InputMessage("Please enter your password")); break; case CurrentState.InvalidUser: mob.Send(new InformationalMessage("Invalid username/password specified.")); this.currentState = CurrentState.FetchUserName; mob.Send(new InputMessage("Please enter your user name")); break; } } /// <summary> /// Receives the players input. /// </summary> /// <param name="sender">The sender.</param> /// <param name="e">The e.</param> void connectedPlayer_ReceivedMessage(object sender, IMessage e) { // Be good memory citizens and clean ourself up after receiving a message. // Not doing this results in duplicate events being registered and memory leaks. this.connectedPlayer.ReceivedMessage -= connectedPlayer_ReceivedMessage; ICommand command = this.GetCommand(e); } /// <summary> /// Gets the Command that the player entered and preps it for execution. /// </summary> /// <param name="command"></param> /// <returns>Returns the ICommand specified.</returns> public Commands.ICommand GetCommand(IMessage command) { if (this.currentState == CurrentState.FetchUserName) { this.connectedPlayer.Name = command.Message; this.currentState = CurrentState.FetchPassword; } else if (this.currentState == CurrentState.FetchPassword) { // find user } return new NoOpCommand(); } /// <summary> /// Cleanups this instance during a state change. /// </summary> public void Cleanup() { // If we have a player instance, we clean up the registered event. if (this.connectedPlayer != null) { this.connectedPlayer.ReceivedMessage -= this.connectedPlayer_ReceivedMessage; } } Maybe my entire FSM isn't wired up in the best way, but I would appreciate input on what would be the best to maintain a stack of state in a MUD game engine, and if my states should be allowed to receive the input from the user or not to check what command was entered before allowing the state manager to switch states. Thanks in advance.

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  • Doing a passable 4X game AI

    - by Extrakun
    I am coding a rather "simple" 4X game (if a 4X game can be simple). It's indie in scope, and I am wondering if there's anyway to come up with a passable AI without having me spending months coding on it. The game has three major decision making portions; spending of production points, spending of movement points and spending of tech points (basically there are 3 different 'currency', currency unspent at end of turn is not saved) Spend Production Points Upgrade a planet (increase its tech and production) Build ships (3 types) Move ships from planets to planets (costing Movement Points) Move to attack Move to fortify Research Tech (can partially research a tech i.e, as in Master of Orion) The plan for me right now is a brute force approach. There are basically 4 broad options for the player - Upgrade planet(s) to its his production and tech output Conquer as many planets as possible Secure as many planets as possible Get to a certain tech as soon as possible For each decision, I will iterate through the possible options and come up with a score; and then the AI will choose the decision with the highest score. Right now I have no idea how to 'mix decisions'. That is, for example, the AI wishes to upgrade and conquer planets at the same time. I suppose I can have another logic which do a brute force optimization on a combination of those 4 decisions.... At least, that's my plan if I can't think of anything better. Is there any faster way to make a passable AI? I don't need a very good one, to rival Deep Blue or such, just something that has the illusion of intelligence. This is my first time doing an AI on this scale, so I dare not try something too grand too. So far I have experiences with FSM, DFS, BFS and A*

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  • Is this a good implementation of a loop in Prolog?

    - by Carles Araguz
    First of all, let me tell you that this happens to be the first time I ask something here, so if it's not the right place to do so, please forgive me. I'm developing a rather complex software that has a Prolog core implementing a FSM. Since I don't want it to stop (ever), I'm trying to write a good loop-like predicate that would work using Prolog's recursion. After a few unsuccessful tries (mainly because of stack problems) I ended up having something similar to this: /* Finite State Transition Network */ transition(st0,evnt0,st1). transition(st1,evnt1,st2). transition(st2,evnt2,st0). fsm_state(state(st0),system(Energy,ActivePayloads),[]) :- /* ... */ transition(st0,evnt0,NextState), !, fsm_state(state(NextState),system(Energy,ActivePayloads),[]). fsm_state(state(st1),system(Energy,ActivePayloads),[]) :- /* ... */ transition(st1,evnt1,NextState), !, fsm_state(state(NextState),system(Energy,ActivePayloads),[0,1,2]). fsm_state(state(st2),system(Energy,ActivePayloads),[P|Params]) :- /* ... */ transition(st2,evnt2,NextState), !, fsm_state(state(NextState),system(Energy,ActivePayloads),[]). start :- Sys = system(10,[]), fsm_state(state(s0),Sys,[]). Is this a good approach?

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  • Operant conditioning algorithm?

    - by Ken
    What's the best way to implement real time operant conditioning (supervised reward/punishment-based learning) for an agent? Should I use a neural network (and what type)? Or something else? I want the agent to be able to be trained to follow commands like a dog. The commands would be in the form of gestures on a touchscreen. I want the agent to be able to be trained to follow a path (in continuous 2D space), make behavioral changes on command (modeled by FSM state transitions), and perform sequences of actions. The agent would be in a simulated physical environment.

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  • VHDL Simulation Timing Behaviour

    - by chris
    I'm trying to write some VHDL code that simply feeds sequential bits from a std_logic_vector into a model of an FSM. However, the bits don't seem to be updating correctly. To try figure out the issue, I have the following code, where instead of getting a bit out of a vector, I'm just toggling the signal x (the same place I'd be getting a bit out). clk <= NOT clk after 10 ns; process(clk) begin if count = 8 then assert false report "Simulation ended" severity failure; elsif (clk = '1') then x <= test1(count); count <= count + 1; end if; end process; EDIT: It appears I was confused.I've put it back to trying to take bit by bit out of the vector. This is the output. I would have thought that on when count is 1, x would take on the value of test1(1) which is a 1.

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  • How to recover from finite-state-machine breakdown?

    - by Earl Grey
    My question may seems very scientific but I think it's a common problem and seasoned developers and programmers hopefully will have some advice to avoid the problem I mention in title. Btw., what I describe bellow is a real problem I am trying to proactively solve in my iOS project, I want to avoid it at all cost. By finite state machine I mean this I have a UI with a few buttons, several session states relevant to that UI and what this UI represents, I have some data which values are partly displayed in the UI, I receive and handle some external triggers (represented by callbacks from sensors). I made state diagrams to better map the relevant scenarios that are desirable and alowable in that UI and application. As I slowly implement the code, the app starts to behave more and more like it should. However, I am not very confident that it is robust enough. My doubts come from watching my own thinking and implementation process as it goes. I was confident that I had everything covered, but it was enough to make a few brute tests in the UI and I quickly realized that there are still gaps in the behavior ..I patched them. However, as each component depends and behaves based on input from some other component, a certain input from user or some external source trigers a chain of events, state changes..etc. I have several components and each behave like this Trigger received on input - trigger and its sender analyzed - output something (a message, a state change) based on analysis The problem is, this is not completely selfcontained, and my components (a database item, a session state, some button's state)...COULD be changed, influenced, deleted, or otherwise modified, outside the scope of the event-chain or desirable scenario. (phone crashes, battery is empty phone turn of suddenly) This will introduce a nonvalid situation into the system, from which the system potentially COULD NOT BE ABLE to recover. I see this (althought people do not realize this is the problem) in many of my competitors apps that are on apple store, customers write things like this "I added three documents, and after going there and there, i cannot open them, even if a see them." or "I recorded videos everyday, but after recording a too log video, I cannot turn of captions on them.., and the button for captions doesn't work".. These are just shortened examples, customers often describe it in more detail..from the descriptions and behavior described in them, I assume that the particular app has a FSM breakdown. So the ultimate question is how can I avoid this, and how to protect the system from blocking itself? EDIT I am talking in the context of one viewcontroller's view on the phone, I mean one part of the application. I Understand the MVC pattern, I have separate modules for distinct functionality..everything I describe is relevant to one canvas on the UI.

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  • Designing a chain of states

    - by devoured elysium
    I want to model a kind of FSM(Finite State Machine). I have a sequence of states (let's say, from StateA to StateZ). This sequence is called a Chain and is implemented internally as a List. I will add states by the order I want them to run. My purpose is to be able to make a sequence of actions in my computer (for example, mouse clicks). (I know this has been done a zillion times). So a state is defined as a: boolean Precondition() <- Checks to see if for this state, some condition is true. For example, if I want to click in the Record button of a program, in this method I would check if the program's process is running or not. If it is, go to the next state in the chain list, otherwise, go to what was defined as the fail state (generally is the first state of them all). IState GetNextState() <- Returns the next state to evaluate. If Precondition() was sucessful, it should yield the next state in the chain otherwise it should yield the fail state. Run() Simply checks the Precondition() and sets the internal data so GetNextState() works as expected. So, a naive approach to this would be something like this: Chain chain = new Chain(); //chain.AddState(new State(Precondition, FailState, NextState) <- Method structure chain.AddState(new State(new WinampIsOpenCondition(), null, new <problem here, I want to referr to a state that still wasn't defined!>); The big problem is that I want to make a reference to a State that at this point still wasn't defined. I could circumvent the problem by using strings when refrering to states and using an internal hashtable, but isn't there a clearer alternative? I could just pass only the pre-condition and failure states in the constructor, having the chain just before execution put in each state the correct next state in a public property but that seems kind of awkward.

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  • ActionScript shiftKey Not Working In Full Screen Mode?

    - by Chunk1978
    i've drawn an ellipse sprite and added it to the display list of a container, which is added to the display list of the stage. to move the sprites with the keyboard arrows, it appears that my shiftModifier:Number variable is not working when the stage's display state is set to full screen. shiftModifier works as it should when the stage's display state is set to Normal. stage.addEventListener(KeyboardEvent.KEY_DOWN, onKeyboardDown); function onKeyboardDown(evt:KeyboardEvent):void { var shiftModifier:Number = 0.25; if (evt.shiftKey) {shiftModifier = 10;} if (evt.keyCode == Keyboard.UP) {ellipse1.y -= shiftModifier;} if (evt.keyCode == Keyboard.DOWN) {ellipse1.y += shiftModifier;} if (evt.keyCode == Keyboard.LEFT) {ellipse1.x -= shiftModifier;} if (evt.keyCode == Keyboard.RIGHT) {ellipse1.x += shiftModifier;} } fsm.addEventListener(MouseEvent.CLICK, toggleFullScreenMode); function toggleFullScreenMode(evt:MouseEvent):void { if (stage.displayState == StageDisplayState.FULL_SCREEN) {stage.displayState = StageDisplayState.NORMAL;} else {stage.displayState = StageDisplayState.FULL_SCREEN;} } full screen is tested in Safari and Firefox.

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  • Is this way of storing typed objects in memory good?

    - by Pindatjuh
    This is an "is this okay, or can it be done better" question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical possition when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignement. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 11111111 11111111 11111111 11111111 Data Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 11111111 11111111 11111111 11111111 Is this okay, or can it be done better?

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