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  • Question about component based design: handling objects interaction

    - by Milo
    I'm not sure how exactly objects do things to other objects in a component based design. Say I have an Obj class. I do: Obj obj; obj.add(new Position()); obj.add(new Physics()); How could I then have another object not only move the ball but have those physics applied. I'm not looking for implementation details but rather abstractly how objects communicate. In an entity based design, you might just have: obj1.emitForceOn(obj2,5.0,0.0,0.0); Any article or explanation to get a better grasp on a component driven design and how to do basic things would be really helpful.

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  • Handling early/late/dropped packets for interpolation in a 3D multiplayer game

    - by Ben Cracknell
    I'm working on a multiplayer game that for the purposes of this question, is most similar to Team Fortress. Each network data packet will contain the 3D position of the target moving object. (this object could be another player) The packets are sent on a fixed interval, and linear interpolation will be used to smooth the transition between packets. Under normal circumstances, interpolation will occur between the second-to-last packet, and the last packet received. The linear interpolation algorithm is the same as this post: Interpolating positions in a multiplayer game I have the same issue as in that post, but the answers don't seem like they will work in my situation. Consider the following scenario: Normal packet timing, everything is okay The next expected packet is late. That's okay, we'll just extrapolate based on previous positions The late packet eventually arrives with corrections to our extrapolation. Now what do we do with its information? The answers on the above post suggest we should just interpolate to this new packet's position, but that would not work at all. If we have already extrapolated past that point in time, moving back would cause rubber-banding. The issue is similar in the case of an early or dropped packet. So I believe what I am looking for is some way to smoothly deal with new information in an ongoing interpolation/extrapolation process. Since I might be moving on to quadratic or even cubic interpolation, it would be great if the same solutiuon could be applied to those as well.

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  • Useful Extensions for SecurityToken Handling - Convert a SecurityToken to Claims

    - by Your DisplayName here!
    That’s a very common one: public static IClaimsPrincipal ToClaimsPrincipal( this SecurityToken token, X509Certificate2 signingCertificate) {     var configuration = CreateStandardConfiguration(signingCertificate);     return token.ToClaimsPrincipal(configuration.CreateDefaultHandlerCollection()); }   public static IClaimsPrincipal ToClaimsPrincipal(this SecurityToken token, X509Certificate2 signingCertificate, string audienceUri) {     var configuration = CreateStandardConfiguration(signingCertificate);     configuration.AudienceRestriction.AudienceMode = AudienceUriMode.Always;     configuration.AudienceRestriction.AllowedAudienceUris.Add(new Uri(audienceUri));     return token.ToClaimsPrincipal(configuration.CreateDefaultHandlerCollection()); }   public static IClaimsPrincipal ToClaimsPrincipal( this SecurityToken token, SecurityTokenHandlerCollection handler) {     var ids = handler.ValidateToken(token);     return ClaimsPrincipal.CreateFromIdentities(ids); }   private static SecurityTokenHandlerConfiguration CreateStandardConfiguration( X509Certificate2 signingCertificate) {     var configuration = new SecurityTokenHandlerConfiguration();     configuration.AudienceRestriction.AudienceMode = AudienceUriMode.Never;     configuration.IssuerNameRegistry = signingCertificate.CreateIssuerNameRegistry();     configuration.IssuerTokenResolver = signingCertificate.CreateSecurityTokenResolver();     configuration.SaveBootstrapTokens = true;     return configuration; }  private static IssuerNameRegistry CreateIssuerNameRegistry(this X509Certificate2 certificate) {     var registry = new ConfigurationBasedIssuerNameRegistry();     registry.AddTrustedIssuer(certificate.Thumbprint, certificate.Subject);     return registry; }   private static SecurityTokenResolver CreateSecurityTokenResolver( this X509Certificate2 certificate) {     var tokens = new List<SecurityToken>     {         new X509SecurityToken(certificate)     };     return SecurityTokenResolver.CreateDefaultSecurityTokenResolver(tokens.AsReadOnly(), true); }   private static SecurityTokenHandlerCollection CreateDefaultHandlerCollection( this SecurityTokenHandlerConfiguration configuration) {     return  SecurityTokenHandlerCollection.CreateDefaultSecurityTokenHandlerCollection(configuration); }  

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  • Should a stack trace be in the error message presented to the user?

    - by Vilx-
    I've got a bit of an argument at my workplace and I'm trying to figure out who is right, and what is the right thing to do. Context: an intranet web application that our customers use for accounting and other ERP stuff. I'm of the opinion that an error message presented to the user (when things crash) should include as much information as possible, including the stack trace. Of course, it has to start with a nice "An Error has occurred, please submit the below information to the developers" in large, friendly letters. My reasoning is that a screenshot of the crashed application will often be the only easily available source of information. Sure, you can try to get a hold of the client's systems administrator(s), attempt to explain where your log files are, etc, but that will probably be slow and painful (talking to the client representatives mostly is). Also, having an immediate and full information is extremely useful in development, where you don't have to go hunting through the log files to find what you need on every exception. (But that could be solved with a configuration switch.) Unfortunately there has been some kind of "Security audit" (no idea how they did that without the sources... but whatever), and they complained about the full exception messages citing them as a security threat. Naturally, the clients (at least one that I know of) has taken this at face value and now demands that the messages be cleaned. I fail to see how a potential attacker could use a stack trace to figure anything out he couldn't have figured out before. Are there any examples, any documented proof of anyone ever doing that? I think that we should fight this foolish idea, but perhaps I'm the fool here, so... Who's right?

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  • Model View Control Issue: Null Pointer Initialization Question [closed]

    - by David Dimalanta
    Good morning again. This is David. Please, I need an urgent help regarding control model view where I making a code that uniquely separating into groups: An Activity Java Class to Display the Interface A View and Function Java Class for Drawing Cards and Display it on the Activity Class The problem is that the result returns a Null Pointer Exception. I have initialize for the ID for Text View and Image View. Under this class "draw_deck.java". Please help me. Here's my code for draw_deck.java: package com.bodapps.inbetween.model; import android.content.Context; import android.view.View; import android.widget.ImageView; import android.widget.TextView; import com.bodapps.inbetween.R; public class draw_deck extends View { public TextView count_label; public ImageView draw_card; private int count; public draw_deck(Context context) { super(context); // TODO Auto-generated constructor stub //I have initialized two widgets for ID. I still don't get it why I got forced closed by Null Pointer Exception thing. draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); count_label = (TextView) findViewById(R.id.Text_View_Count_Card); } public void draw(int s, int c, String strSuit, String strValue, Pile pile, Context context) { //super(context); //Just printing the card drawn from pile int suit, value = 1; draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); count_label = (TextView) findViewById(R.id.Text_View_Count_Card); Card card; if(!pile.isEmpty()) //Setting it to IF statement displays the card one by one. { card = pile.drawFromPile(); //Need to check first if card is null. if (card != null) { //draws an extra if (card != null) { //Get suit of card to print out. suit = card.getSuit(); switch (suit) { case CardInfo.DIAMOND: strSuit = "DIAMOND"; s=0; break; case CardInfo.HEART: strSuit = "HEART"; s=1; break; case CardInfo.SPADE: strSuit = "SPADE"; s=2; break; case CardInfo.CLUB: strSuit = "CLUB"; s=3; break; } //Get value of card to print out. value = card.getValue(); switch (value) { case CardInfo.ACE: strValue = "ACE"; c=0; break; case CardInfo.TWO: c=1; break; case CardInfo.THREE: strValue = "THREE"; c=2; break; case CardInfo.FOUR: strValue = "FOUR"; c=3; break; case CardInfo.FIVE: strValue = "FIVE"; c=4; break; case CardInfo.SIX: strValue = "SIX"; c=4; break; case CardInfo.SEVEN: strValue = "SEVEN"; c=4; break; case CardInfo.EIGHT: strValue = "EIGHT"; c=4; break; case CardInfo.NINE: strValue = "NINE"; c=4; break; case CardInfo.TEN: strValue = "TEN"; c=4; break; case CardInfo.JACK: strValue = "JACK"; c=4; break; case CardInfo.QUEEN: strValue = "QUEEN"; c=4; break; case CardInfo.KING: strValue = "KING"; c=4; break; } } } }// //Below two lines of code, this is where issued the Null Pointer Exception. draw_card.setImageResource(deck[s][c]); count_label.setText(new StringBuilder(strValue).append(" of ").append(strSuit).append(String.valueOf(" " + count++)).toString()); } //Choice of Suits in a Deck public Integer[][] deck = { //Array Group 1 is [0][0] (No. of Cards: 4 - DIAMOND) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 2 is [1][0] (No. of Cards: 4 - HEART) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 3 is [2][0] (No. of Cards: 4 - SPADE) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, //Array Group 4 is [3][0] (No. of Cards: 4 - CLUB) { R.drawable.card_dummy_1, R.drawable.card_dummy_2, R.drawable.card_dummy_4, R.drawable.card_dummy_5, R.drawable.card_dummy_3 }, }; } And this one of the activity class, Player_Mode_2.java: package com.bodapps.inbetween; import java.util.Random; import android.app.Activity; import android.app.Dialog; import android.content.Context; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import android.widget.TextView; import android.widget.Toast; import com.bodapps.inbetween.model.Card; import com.bodapps.inbetween.model.Pile; import com.bodapps.inbetween.model.draw_deck; /* * * Public class for Two-Player mode. * */ public class Player_Mode_2 extends Activity { //Image Views private ImageView draw_card; private ImageView player_1; private ImageView player_2; private ImageView icon; //Buttons private Button set_deck; //Edit Texts private EditText enter_no_of_decks; //text Views private TextView count_label; //Integer Data Types private int no_of_cards, count; private int card_multiplier; //Contexts final Context context = this; //Pile Model public Pile pile; //Card Model public Card card; //create View @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.play_2_player_mode); //-----[ Search for Views ]----- //Initialize for Image View draw_card = (ImageView) findViewById(R.id.IV_Draw_Card); player_1 = (ImageView) findViewById(R.id.IV_Player_1_Card); player_2 = (ImageView) findViewById(R.id.IV_Player_2_Card); //Initialize for Text view or Label count_label = (TextView) findViewById(R.id.Text_View_Count_Card); //-----[ Adding Values ]----- //Integer Values count = 0; no_of_cards = 0; //-----[ Adding Dialog ]----- //Initializing Dialog final Dialog deck_dialog = new Dialog(context); deck_dialog.setContentView(R.layout.dialog); deck_dialog.setTitle("Deck Dialog"); //-----[ Initializing Views for Dialog's Contents ]----- //Initialize for Edit Text enter_no_of_decks = (EditText) deck_dialog.findViewById(R.id.Edit_Text_Set_Number_of_Decks); //Initialize for Button set_deck = (Button) deck_dialog.findViewById(R.id.Button_Deck); //-----[ Setting onClickListener() ]----- //Set Event Listener for Image view draw_card.setOnClickListener(new Draw_Card_Model()); //Set Event Listener for Setting the Deck set_deck.setOnClickListener(new OnClickListener() { public void onClick(View v) { if(card_multiplier <= 8) { //Use "Integer.parseInt()" method to instantly convert from String to int value. card_multiplier = Integer.parseInt(enter_no_of_decks.getText().toString()); //Shuffling cards... pile = new Pile(card_multiplier); //Multiply no. of decks //Dismiss or close the dialog. deck_dialog.dismiss(); } else { Toast.makeText(getApplicationContext(), "Please choose a number from 1 to 8.", Toast.LENGTH_SHORT).show(); } } }); //Show dialog. deck_dialog.show(); } //Shuffling the Array public void Shuffle_Cards(Integer[][] Shuffle_Deck) { Random random = new Random(); for(int i = Shuffle_Deck[no_of_cards].length - 1; i >=0; i--) { int Index = random.nextInt(i + 1); //Simple Swapping Integer swap = Shuffle_Deck[card_multiplier-1][Index]; Shuffle_Deck[card_multiplier-1][Index] = Shuffle_Deck[card_multiplier-1][i]; Shuffle_Deck[card_multiplier-1][i] = swap; } } //Private Class for Random Card Draw private class Draw_Card_Model implements OnClickListener { public void onClick(View v) { //Just printing the card drawn from pile int suit = 0, value = 0; String strSuit = "", strValue = ""; draw_deck draw = new draw_deck(context); //This line is where issued the Null Pointer Exception. if (count == card_multiplier*52) { // A message shows up when all cards are draw out. Toast.makeText(getApplicationContext(), "All cards have been used up.", Toast.LENGTH_SHORT).show(); draw_card.setEnabled(false); } else { draw.draw(suit, value, strSuit, strValue, pile, context); count_label.setText(count); //This is where I got force closed error, although "int count" have initialized the number. This was supposed to accept in the setText() method. count++; } } } } Take note that the issues on Null Pointer Exception is the Image View and the Edit Text. I got to test it. Thanks. If you have any info about my question, let me know it frankly.

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  • Was API hooking done as needed for Stuxnet to work? I don't think so

    - by The Kaykay
    Caveat: I am a political science student and I have tried my level best to understand the technicalities; if I still sound naive please overlook that. In the Symantec report on Stuxnet, the authors say that once the worm infects the 32-bit Windows computer which has a WINCC setup on it, Stuxnet does many things and that it specifically hooks the function CreateFileA(). This function is the route which the worm uses to actually infect the .s7p project files that are used to program the PLCs. ie when the PLC programmer opens a file with .s7p the control transfers to the hooked function CreateFileA_hook() instead of CreateFileA(). Once Stuxnet gains the control it covertly inserts code blocks into the PLC without the programmers knowledge and hides it from his view. However, it should be noted that there is also one more function called CreateFileW() which does the same task as CreateFileA() but both work on different character sets. CreateFileA works with ASCII character set and CreateFileW works with wide characters or Unicode character set. Farsi (the language of the Iranians) is a language that needs unicode character set and not ASCII Characters. I'm assuming that the developers of any famous commercial software (for ex. WinCC) that will be sold in many countries will take 'Localization' and/or 'Internationalization' into consideration while it is being developed in order to make the product fail-safe ie. the software developers would use UNICODE while compiling their code and not just 'ASCII'. Thus, I think that CreateFileW() would have been invoked on a WINCC system in Iran instead of CreateFileA(). Do you agree? My question is: If Stuxnet has hooked only the function CreateFileA() then based on the above assumption there is a significant chance that it did not work at all? I think my doubt will get clarified if: my assumption is proved wrong, or the Symantec report is proved incorrect. Please help me clarify this doubt. Note: I had posted this question on the general stackexchange website and did not get appropriate responses that I was looking for so I'm posting it here.

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  • How to void checked exceptions in Java?

    - by deamon
    I consider checked exception for a design mistake in the Java language. They lead to leaky abstractions and a lot of clutter in the code. It seems that they force the programmer to handle exceptions early although they are in most cases better handled lately. So my question is how to avoid checked exception? My idea is to execute the actual code inside an exception translator using lambda expressions. Example: ExceptionConverter.convertToRuntimeException(() => { // do things that could throw checked exceptions here }); If for example a IOException occurs it gets rethrown as an exception with the same name but from a different class hierarchy (based on RuntimeException). This approach would effectivly remove the need to handle or declare checked exceptions. Exceptions could then be handled where and if it makes sense. Another solution would be to declare IOException throws Exception on each method. What do you think which solution is better? Do you know any better approach to avoid (suppress) checked exceptions in Java?

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  • Handling Configuration Changes in Windows Azure Applications

    - by Your DisplayName here!
    While finalizing StarterSTS 1.5, I had a closer look at lifetime and configuration management in Windows Azure. (this is no new information – just some bits and pieces compiled at one single place – plus a bit of reality check) When dealing with lifetime management (and especially configuration changes), there are two mechanisms in Windows Azure – a RoleEntryPoint derived class and a couple of events on the RoleEnvironment class. You can find good documentation about RoleEntryPoint here. The RoleEnvironment class features two events that deal with configuration changes – Changing and Changed. Whenever a configuration change gets pushed out by the fabric controller (either changes in the settings section or the instance count of a role) the Changing event gets fired. The event handler receives an instance of the RoleEnvironmentChangingEventArgs type. This contains a collection of type RoleEnvironmentChange. This in turn is a base class for two other classes that detail the two types of possible configuration changes I mentioned above: RoleEnvironmentConfigurationSettingsChange (configuration settings) and RoleEnvironmentTopologyChange (instance count). The two respective classes contain information about which configuration setting and which role has been changed. Furthermore the Changing event can trigger a role recycle (aka reboot) by setting EventArgs.Cancel to true. So your typical job in the Changing event handler is to figure if your application can handle these configuration changes at runtime, or if you rather want a clean restart. Prior to the SDK 1.3 VS Templates – the following code was generated to reboot if any configuration settings have changed: private void RoleEnvironmentChanging(object sender, RoleEnvironmentChangingEventArgs e) {     // If a configuration setting is changing     if (e.Changes.Any(change => change is RoleEnvironmentConfigurationSettingChange))     {         // Set e.Cancel to true to restart this role instance         e.Cancel = true;     } } This is a little drastic as a default since most applications will work just fine with changed configuration – maybe that’s the reason this code has gone away in the 1.3 SDK templates (more). The Changed event gets fired after the configuration changes have been applied. Again the changes will get passed in just like in the Changing event. But from this point on RoleEnvironment.GetConfigurationSettingValue() will return the new values. You can still decide to recycle if some change was so drastic that you need a restart. You can use RoleEnvironment.RequestRecycle() for that (more). As a rule of thumb: When you always use GetConfigurationSettingValue to read from configuration (and there is no bigger state involved) – you typically don’t need to recycle. In the case of StarterSTS, I had to abstract away the physical configuration system and read the actual configuration (either from web.config or the Azure service configuration) at startup. I then cache the configuration settings in memory. This means I indeed need to take action when configuration changes – so in my case I simply clear the cache, and the new config values get read on the next access to my internal configuration object. No downtime – nice! Gotcha A very natural place to hook up the RoleEnvironment lifetime events is the RoleEntryPoint derived class. But with the move to the full IIS model in 1.3 – the RoleEntryPoint methods get executed in a different AppDomain (even in a different process) – see here.. You might no be able to call into your application code to e.g. clear a cache. Keep that in mind! In this case you need to handle these events from e.g. global.asax.

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  • Basic AI FSM - Handling state transition

    - by Galvanize
    I'm starting to study on how to implement game AI, and it seems to me that a very simple FSM for my Pong demo would be a nice way to start. My vision on implementing this would be to have a basic state interface and a class for each state, then the NPC would have an instance of the current state. The class should have an update method and directions on wich state to go next, depending on the event received. The question is: How do I handle this event? Should I have a regular addEventListener and a costum event system? Or should I check on update for the things that could change the current state? I'm feeling a bit lost, I feel I have a good grasp on the FSM concept but a good implementation seems tricky, thanks in advance.

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  • Which logfile(s) log(s) errors reading a cd?

    - by Robert Vila
    I introduce a CD-RW, maybe blank (I really don't know), and after a little movement inside the reader, the CD is ejected without any message at all. I would like to know what is going on and the reason why it is ejected. How can I know that in Natty. The CD reader is working OK because I can read other CD's. It only gave me problems writing from Natty, a few days ago, but with MacOS there was no problem. Thank you Edit: Maybe there is no error, but then, how can I know what is in the Cd if there is anything?

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  • Decision for Unchecked Exceptions in Scala

    - by Jatin
    As a java programmer, I have always been critical of Unchecked Exceptions. Mostly programmers use it as an en-route to coding easiness only to create trouble later. Also the programs (though untidy) with checked exceptions are much robust compared to unchecked counterparts. Surprisingly in Scala, there is nothing called Checked Exceptions. All the Java checked and unchecked are unchecked in Scala. What is the motivation behind this decision? For me it opens wide range of problems when using any external code. And if by chance the documentation is poor, it results in KILL.

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  • Handling window resize with arbitrary aspect ratios

    - by DormoTheNord
    I'm currently making a 2D game using SFML. I want the aspect ratio to be maintained when the user resizes the window. I also want the game to work with any arbitrary aspect ratio (like any media player would). Here is the code I have so far: void os::GameEngine::setCameraViewport() { sf::FloatRect tempViewport; float viewAspectRatio = (float)aspectRatio.x / aspectRatio.y; float screenAspectRatio = (float)gameWindow.getSize().x / gameWindow.getSize().y; if (viewAspectRatio > screenAspectRatio) { // Viewport is wider than screen, fit on X } else if (viewAspectRatio < screenAspectRatio) { // Screen is wider than viewport, fit on Y } else // window aspect ratio matches view aspect ratio { tempViewport.height = 1; tempViewport.width = 1; tempViewport.left = 0; tempViewport.top = 0; } viewport = tempViewport; camera.setViewport(viewport); gameWindow.setView(camera); } The problem is I'm having trouble with the logic to determine the properties of the viewport.

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  • Importing tab delimited file into array in Visual Basic 2013 [migrated]

    - by JaceG
    I am needing to import a tab delimited text file that has 11 columns and an unknown number of rows (always minimum 3 rows). I would like to import this text file as an array and be able to call data from it as needed, throughout my project. And then, to make things more difficult, I need to replace items in the array, and even add more rows to it as the project goes on (all at runtime). Hopefully someone can suggest code corrections or useful methods. I'm hoping to use something like the array style sMyStrings(3,2), which I believe would be the easiest way to control my data. Any help is gladly appreciated, and worthy of a slab of beer. Here's the coding I have so far: Imports System.IO Imports Microsoft.VisualBasic.FileIO Public Class Main Dim strReadLine As String Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load Dim sReader As IO.StreamReader = Nothing Dim sRawString As String = Nothing Dim sMyStrings() As String = Nothing Dim intCount As Integer = -1 Dim intFullLoop As Integer = 0 If IO.File.Exists("C:\MyProject\Hardware.txt") Then ' Make sure the file exists sReader = New IO.StreamReader("C:\MyProject\Hardware.txt") Else MsgBox("File doesn't exist.", MsgBoxStyle.Critical, "Error") End End If Do While sReader.Peek >= 0 ' Make sure you can read beyond the current position sRawString = sReader.ReadLine() ' Read the current line sMyStrings = sRawString.Split(New Char() {Chr(9)}) ' Separate values and store in a string array For Each s As String In sMyStrings ' Loop through the string array intCount = intCount + 1 ' Increment If TextBox1.Text <> "" Then TextBox1.Text = TextBox1.Text & vbCrLf ' Add line feed TextBox1.Text = TextBox1.Text & s ' Add line to debug textbox If intFullLoop > 14 And intCount > -1 And CBool((intCount - 0) / 11 Mod 0) Then cmbSelectHinge.Items.Add(sMyStrings(intCount)) End If Next intCount = -1 intFullLoop = intFullLoop + 1 Loop End Sub

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  • Is goto to improve DRY-ness OK?

    - by Marco Scannadinari
    My code has many checks to detect errors in various cases (many conditions would result in the same error), inside a function returning an error struct. Instead of looking like this: err_struct myfunc(...) { err_struct error = { .error = false }; ... if(something) { error.error = true; error.description = "invalid input"; return error; } ... case 1024: error.error = true; error.description = "invalid input"; // same error, but different detection scenario return error; break; // don't comment on this break please (EDIT: pun unintended) ... Is use of goto in the following context considered better than the previous example? err_struct myfunc(...) { err_struct error = { .error = false }; ... if(something) goto invalid_input; ... case 1024: goto invalid_input; break; return error; invalid_input: error.error = true; error.description = "invalid input"; return error;

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  • Where should I handle fatal exceptions

    - by Puckl
    For example, I have a controller that loads a file and hands it over to the processing. Should I handle the exception in the file loader and return Null if something is wrong, or should I throw the exception and handle it in the controller? Without the file the rest of the program can´t work. Where should I handle a exception that shuts down the program properly? I want to shut down an Android application properly.

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  • Common practice in handling bounce message

    - by foodil
    At now I mainly create a mail account separately (with different domain name [email protected]) and i add this mail as one return path. So the bounce message will only go to that mailbox and i parse the mail message one by one to check the failure receipent and the error code, then i convert the error code to the actual error message. Finally, the error message and the fail receipent's mail are post to my system and let my system user check the bounce information. Is it a common practice? Since i am worry about the mail other from bounce message have sent to my mail box, that would be a disaster if i parse them without filter them out, but how can i filter out between bounce message and normal mail? Thank you for any kind of help.

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  • Any good reason open files in text mode?

    - by Tinctorius
    (Almost-)POSIX-compliant operating systems and Windows are known to distinguish between 'binary mode' and 'text mode' file I/O. While the former mode doesn't transform any data between the actual file or stream and the application, the latter 'translates' the contents to some standard format in a platform-specific manner: line endings are transparently translated to '\n' in C, and some platforms (CP/M, DOS and Windows) cut off a file when a byte with value 0x1A is found. These transformations seem a little useless to me. People share files between computers with different operating systems. Text mode would cause some data to be handled differently across some platforms, so when this matters, one would probably use binary mode instead. As an example: while Windows uses the sequence CR LF to end a line in text mode, UNIX text mode will not treat CR as part of the line ending sequence. Applications would have to filter that noise themselves. Older Mac versions only use CR in text mode as line endings, so neither UNIX nor Windows would understand its files. If this matters, a portable application would probably implement the parsing by itself instead of using text mode. Implementing newline interpretation in the parser might also remove some overhead of using text mode, as buffers would need to be rewritten (and possibly resized) before returning to the application, while this may be less efficient than when it would happen in the application instead. So, my question is: is there any good reason to still rely on the host OS to translate line endings and file truncation?

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  • Handling cameras in a large scale game engine

    - by Hannesh
    What is the correct, or most elegant, way to manage cameras in large game engines? Or should I ask, how does everybody else do it? The methods I can think of are: Binding cameras straight to the engine; if someone needs to render something, they bind their own camera to the graphics engine which is in use until another camera is bound. A camera stack; a small task can push its own camera onto the stack, and pop it off at the end to return to the "main" camera. Attaching a camera to a shader; Every shader has exactly one camera bound to it, and when the shader is used, that camera is set by the engine when the shader is in use. This allows me to implement a bunch of optimizations on the engine side. Are there other ways to do it?

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  • Handling & processing credit card payments

    - by Bob Jansen
    I'm working on program that charges customers on a pay as you go per month modal. This means that instead of the customers paying their invoices at the start of the month, they will have to pay at the end of the month. In order to secure the payments I want my customers credit card information stored so that they can be charged automatically at the end of the month. I do not have the resources, time, or risk to handle and store my customers credit card information on my servers and am looking for a third party solution. I'm a tad overwhelmed by all the different options and services that are out there and was wondering if anyone with experience have any recommendations and tips. I'm having difficulty finding services that allow me to to store my customers credit card information and charge them automatically. Most of them seem to offer an invoice styled approach.

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  • I've been told that Exceptions should only be used in exceptional cases. How do I know if my case is exceptional?

    - by tieTYT
    My specific case here is that the user can pass in a string into the application, the application parses it and assigns it to structured objects. Sometimes the user may type in something invalid. For example, their input may describe a person but they may say their age is "apple". Correct behavior in that case is roll back the transaction and to tell the user an error occurred and they'll have to try again. There may be a requirement to report on every error we can find in the input, not just the first. In this case, I argued we should throw an exception. He disagreed, saying, "Exceptions should be exceptional: It's expected that the user may input invalid data, so this isn't an exceptional case" I didn't really know how to argue that point, because by definition of the word, he seems to be right. But, it's my understanding that this is why Exceptions were invented in the first place. It used to be you had to inspect the result to see if an error occurred. If you failed to check, bad things could happen without you noticing. Without exceptions every level of the stack needs to check the result of the methods they call and if a programmer forgets to check in one of these levels, the code could accidentally proceed and save invalid data (for example). Seems more error prone that way. Anyway, feel free to correct anything I've said here. My main question is if someone says Exceptions should be exceptional, how do I know if my case is exceptional?

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  • Criteria for selecting timeout value?

    - by stijn
    Situation: a piece of software reads frames of data from a file in a seperate thread and puts it on a queue, emptied by another thread. That second thread periodically checks on the queue and fails rather gracefully, by showing an error message stating the read timed out, if no data is available within a certain amount of time. Initially this timeout was set to 200mSec. There was no real reasoning behind that constant though, but it worked fine. We measured on a couple of machines and for large data frames, larger than what would be used by customers, a read took like 20mSec whith no other load on the machine. However one customer now gets timeout errors now and then (on the second try all is fine, probably the file is in cache or the virus scanner leaves it alone). The programmers are like 'well, yeah, but that customer's machine is full of cruft, virus scanners, tons of unneeded background processes etc'. Of course the customer is like 'hey this should just work, shouldn't it'? While the programers have a point, since the software is heavy enough to validate the need for a dedicated machine, that does not make the customer happy. Increasing the timeout to 2 seconds, for example, solves the problem. But I'd like to make a proper decision now instead of just randomly pick some magic constant that is probably ok in 99% of cases. What criteria should be used for that? We could just pick a large number, but that feels wrong. (and then we end up with a program that has the horrible bahaviour of hanging when trying to read from a disconnected drive for instance, whereas we'd rather make it show an error right away). Or we could make the timeout value a user setting, but then we need to ducument it clearly and even then not all customers are tech savy enough to really understand what it does. Or we could try and wait until another customer reports timeouts and increase the value again. And again. Until we find something ok for 99.99% of the cases.. Any good practice for this type of situation?

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  • Handling buildings in isometric tile based games

    - by MustSeeMelons
    A simple question, to which i couldn't find a definitive answer - how to manage buildings on a tiled map? Should the building be sliced in to tiles or one big image? EDIT: The game is being built from scratch using C++/SDL 2.0, it will be a turn based strategy, something like Fallout 1 & 2 without the hex grid, a simple square grid, where the Y axis is squished by 50%. Buildings can span multiple tiles, the characters move tile by tile. For now, the terrain is completely flat. Some basic functionality is in place, so I'm aiming to advancing the terrain and levels them selves - adding buildings, gates, cliffs, not sure about the elevation.

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  • SSIS 2008 Configuration Settings Handling Logic for Variables Visualized

    - by Compudicted
    There are many articles discussing the specifics of how the configuration settings are applied including the differences between SSIS 2005 and 2008 version implementations, however this topic keeps resurfacing on MSDN’s SSIS Forum. I thought it could be useful to cover the logic aspect visually. Below is a diagram explaining the basic flow of a variable setting for a case when no parent package is involved.   As you can see the run time stage ignores any command line flags for variables already set in the config file, I realize this is not stressed enough in many publications. Besides, another interesting fact is that the command line dtexec tool is case sensitive for the portion following the package keyword, I mean if you specify your flag to set a new value for a variable like dtexec /f Package.dtsx -set \package.variables[varPkgMyDate].value;02/01/2011 (notice the lover case v in .value) You will get errors. By capitalizing the keyword the package runs successfully.

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  • Effective handling of variables in non-object oriented programming

    - by srnka
    What is the best method to use and share variables between functions in non object-oriented program languages? Let's say that I use 10 parameters from DB, ID and 9 other values linked to it. I need to work with all 10 parameters in many functions. I can do it next ways: 1. call functions only with using ID and in every function get the other parameters from DB. Advantage: local variables are clear visible, there is only one input parameter to function Disadvantage: it's slow and there are the same rows for getting parameters in every function, which makes function longer and not so clear 2. call functions with all 10 parameters Advantage: working with local variables, clear function code Disadvantage: many input parameters, what is not nice 3. getting parameters as global variables once and using them everywhere Advantage - clearer code, shorter functions, faster processing Disadvantage - global variables - loosing control of them, possibility of unwanted overwriting (Especially when some functions should change their values) Maybe there is some another way how to implement this and make program cleaner and more effective. Can you say which way is the best for solving this issue?

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  • Handling player/background movements in 2D games

    - by lukeluke
    Suppose you have your animated character controlled by the player and a 2D world (like the old 2D side-scrolling games). When the user press right on the keyboard, the background is moved to the right. If the path is always horizontal, this is simple to do (incrementation/decrementation of the x-coordinate). But suppose that the path is instead a polygonal chain. My questions are: How do you move the background? How do you move the background if the game objects are managed with a physics engine like box2D?

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