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  • Creating an object that is ready to be used & unset properties - with IoC

    - by GetFuzzy
    I have a question regarding the specifics of object creation and the usage of properties. A best practice is to put all the properties into a state such that the object is useful when its created. Object constructors help ensure that required dependencies are created. I've found myself following a pattern lately, and then questioning its appropriateness. The pattern looks like this... public class ThingProcesser { public List<Thing> CalculatedThings { get; set; } public ThingProcesser() { CalculatedThings = new List<Thing>(); } public double FindCertainThing() { CheckForException(); foreach (var thing in CalculatedThings) { //do some stuff with things... } } public double FindOtherThing() { CheckForException(); foreach (var thing in CalculatedThings) { //do some stuff with things... } } private void CheckForException() { if (CalculatedThings.Count < 2) throw new InvalidOperationException("Calculated things must have more than 2 items"); } } The list of items is not being changed, just looked through by the methods. There are several methods on the class, and to avoid having to pass the list of things to each function as a method parameter, I set it once on the class. While this works, does it violate the principle of least astonishment? Since starting to use IoC I find myself not sticking things into the constructor, to avoid having to use a factory pattern. For example, I can argue with myself and say well the ThingProcessor really needs a List to work, so the object should be constructed like this. public class ThingProcesser { public List<Thing> CalculatedThings { get; set; } public ThingProcesser(List<Thing> calculatedThings) { CalculatedThings = calculatedThings; } } However, if I did this, it would complicate things for IoC, and this scenario hardly seems appropriate for something like the factory pattern. So in summary, are there some good guidelines for when something should be part of the object state, vs. passed as a method parameter? When using IoC, is the factory pattern the best way to deal with objects that need created with state? If something has to be passed to multiple methods in a class, does that render it a good candidate to be part of the objects state?

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  • Elfsign Object Signing on Solaris

    - by danx
    Elfsign Object Signing on Solaris Don't let this happen to you—use elfsign! Solaris elfsign(1) is a command that signs and verifies ELF format executables. That includes not just executable programs (such as ls or cp), but other ELF format files including libraries (such as libnvpair.so) and kernel modules (such as autofs). Elfsign has been available since Solaris 10 and ELF format files distributed with Solaris, since Solaris 10, are signed by either Sun Microsystems or its successor, Oracle Corporation. When an ELF file is signed, elfsign adds a new section the ELF file, .SUNW_signature, that contains a RSA public key signature and other information about the signer. That is, the algorithm used, algorithm OID, signer CN/OU, and time stamp. The signature section can later be verified by elfsign or other software by matching the signature in the file agains the ELF file contents (excluding the signature). ELF executable files may also be signed by a 3rd-party or by the customer. This is useful for verifying the origin and authenticity of executable files installed on a system. The 3rd-party or customer public key certificate should be installed in /etc/certs/ to allow verification by elfsign. For currently-released versions of Solaris, only cryptographic framework plugin libraries are verified by Solaris. However, all ELF files may be verified by the elfsign command at any time. Elfsign Algorithms Elfsign signatures are created by taking a digest of the ELF section contents, then signing the digest with RSA. To verify, one takes a digest of ELF file and compares with the expected digest that's computed from the signature and RSA public key. Originally elfsign took a MD5 digest of a SHA-1 digest of the ELF file sections, then signed the resulting digest with RSA. In Solaris 11.1 then Solaris 11.1 SRU 7 (5/2013), the elfsign crypto algorithms available have been expanded to keep up with evolving cryptography. The following table shows the available elfsign algorithms: Elfsign Algorithm Solaris Release Comments elfsign sign -F rsa_md5_sha1   S10, S11.0, S11.1 Default for S10. Not recommended* elfsign sign -F rsa_sha1 S11.1 Default for S11.1. Not recommended elfsign sign -F rsa_sha256 S11.1 patch SRU7+   Recommended ___ *Most or all CAs do not accept MD5 CSRs and do not issue MD5 certs due to MD5 hash collision problems. RSA Key Length. I recommend using RSA-2048 key length with elfsign is RSA-2048 as the best balance between a long expected "life time", interoperability, and performance. RSA-2048 keys have an expected lifetime through 2030 (and probably beyond). For details, see Recommendation for Key Management: Part 1: General, NIST Publication SP 800-57 part 1 (rev. 3, 7/2012, PDF), tables 2 and 4 (pp. 64, 67). Step 1: create or obtain a key and cert The first step in using elfsign is to obtain a key and cert from a public Certificate Authority (CA), or create your own self-signed key and cert. I'll briefly explain both methods. Obtaining a Certificate from a CA To obtain a cert from a CA, such as Verisign, Thawte, or Go Daddy (to name a few random examples), you create a private key and a Certificate Signing Request (CSR) file and send it to the CA, following the instructions of the CA on their website. They send back a signed public key certificate. The public key cert, along with the private key you created is used by elfsign to sign an ELF file. The public key cert is distributed with the software and is used by elfsign to verify elfsign signatures in ELF files. You need to request a RSA "Class 3 public key certificate", which is used for servers and software signing. Elfsign uses RSA and we recommend RSA-2048 keys. The private key and CSR can be generated with openssl(1) or pktool(1) on Solaris. Here's a simple example that uses pktool to generate a private RSA_2048 key and a CSR for sending to a CA: $ pktool gencsr keystore=file format=pem outcsr=MYCSR.p10 \ subject="CN=canineswworks.com,OU=Canine SW object signing" \ outkey=MYPRIVATEKEY.key $ openssl rsa -noout -text -in MYPRIVATEKEY.key Private-Key: (2048 bit) modulus: 00:d2:ef:42:f2:0b:8c:96:9f:45:32:fc:fe:54:94: . . . [omitted for brevity] . . . c9:c7 publicExponent: 65537 (0x10001) privateExponent: 26:14:fc:49:26:bc:a3:14:ee:31:5e:6b:ac:69:83: . . . [omitted for brevity] . . . 81 prime1: 00:f6:b7:52:73:bc:26:57:26:c8:11:eb:6c:dc:cb: . . . [omitted for brevity] . . . bc:91:d0:40:d6:9d:ac:b5:69 prime2: 00:da:df:3f:56:b2:18:46:e1:89:5b:6c:f1:1a:41: . . . [omitted for brevity] . . . f3:b7:48:de:c3:d9:ce:af:af exponent1: 00:b9:a2:00:11:02:ed:9a:3f:9c:e4:16:ce:c7:67: . . . [omitted for brevity] . . . 55:50:25:70:d3:ca:b9:ab:99 exponent2: 00:c8:fc:f5:57:11:98:85:8e:9a:ea:1f:f2:8f:df: . . . [omitted for brevity] . . . 23:57:0e:4d:b2:a0:12:d2:f5 coefficient: 2f:60:21:cd:dc:52:76:67:1a:d8:75:3e:7f:b0:64: . . . [omitted for brevity] . . . 06:94:56:d8:9d:5c:8e:9b $ openssl req -noout -text -in MYCSR.p10 Certificate Request: Data: Version: 2 (0x2) Subject: OU=Canine SW object signing, CN=canineswworks.com Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 bit) Modulus: 00:d2:ef:42:f2:0b:8c:96:9f:45:32:fc:fe:54:94: . . . [omitted for brevity] . . . c9:c7 Exponent: 65537 (0x10001) Attributes: Signature Algorithm: sha1WithRSAEncryption b3:e8:30:5b:88:37:68:1c:26:6b:45:af:5e:de:ea:60:87:ea: . . . [omitted for brevity] . . . 06:f9:ed:b4 Secure storage of RSA private key. The private key needs to be protected if the key signing is used for production (as opposed to just testing). That is, protect the key to protect against unauthorized signatures by others. One method is to use a PIN-protected PKCS#11 keystore. The private key you generate should be stored in a secure manner, such as in a PKCS#11 keystore using pktool(1). Otherwise others can sign your signature. Other secure key storage mechanisms include a SCA-6000 crypto card, a USB thumb drive stored in a locked area, a dedicated server with restricted access, Oracle Key Manager (OKM), or some combination of these. I also recommend secure backup of the private key. Here's an example of generating a private key protected in the PKCS#11 keystore, and a CSR. $ pktool setpin # use if PIN not set yet Enter token passphrase: changeme Create new passphrase: Re-enter new passphrase: Passphrase changed. $ pktool gencsr keystore=pkcs11 label=MYPRIVATEKEY \ format=pem outcsr=MYCSR.p10 \ subject="CN=canineswworks.com,OU=Canine SW object signing" $ pktool list keystore=pkcs11 Enter PIN for Sun Software PKCS#11 softtoken: Found 1 asymmetric public keys. Key #1 - RSA public key: MYPRIVATEKEY Here's another example that uses openssl instead of pktool to generate a private key and CSR: $ openssl genrsa -out cert.key 2048 $ openssl req -new -key cert.key -out MYCSR.p10 Self-Signed Cert You can use openssl or pktool to create a private key and a self-signed public key certificate. A self-signed cert is useful for development, testing, and internal use. The private key created should be stored in a secure manner, as mentioned above. The following example creates a private key, MYSELFSIGNED.key, and a public key cert, MYSELFSIGNED.pem, using pktool and displays the contents with the openssl command. $ pktool gencert keystore=file format=pem serial=0xD06F00D lifetime=20-year \ keytype=rsa hash=sha256 outcert=MYSELFSIGNED.pem outkey=MYSELFSIGNED.key \ subject="O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com" $ pktool list keystore=file objtype=cert infile=MYSELFSIGNED.pem Found 1 certificates. 1. (X.509 certificate) Filename: MYSELFSIGNED.pem ID: c8:24:59:08:2b:ae:6e:5c:bc:26:bd:ef:0a:9c:54:de:dd:0f:60:46 Subject: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Issuer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Not Before: Oct 17 23:18:00 2013 GMT Not After: Oct 12 23:18:00 2033 GMT Serial: 0xD06F00D0 Signature Algorithm: sha256WithRSAEncryption $ openssl x509 -noout -text -in MYSELFSIGNED.pem Certificate: Data: Version: 3 (0x2) Serial Number: 3496935632 (0xd06f00d0) Signature Algorithm: sha256WithRSAEncryption Issuer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Validity Not Before: Oct 17 23:18:00 2013 GMT Not After : Oct 12 23:18:00 2033 GMT Subject: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 bit) Modulus: 00:bb:e8:11:21:d9:4b:88:53:8b:6c:5a:7a:38:8b: . . . [omitted for brevity] . . . bf:77 Exponent: 65537 (0x10001) Signature Algorithm: sha256WithRSAEncryption 9e:39:fe:c8:44:5c:87:2c:8f:f4:24:f6:0c:9a:2f:64:84:d1: . . . [omitted for brevity] . . . 5f:78:8e:e8 $ openssl rsa -noout -text -in MYSELFSIGNED.key Private-Key: (2048 bit) modulus: 00:bb:e8:11:21:d9:4b:88:53:8b:6c:5a:7a:38:8b: . . . [omitted for brevity] . . . bf:77 publicExponent: 65537 (0x10001) privateExponent: 0a:06:0f:23:e7:1b:88:62:2c:85:d3:2d:c1:e6:6e: . . . [omitted for brevity] . . . 9c:e1:e0:0a:52:77:29:4a:75:aa:02:d8:af:53:24: c1 prime1: 00:ea:12:02:bb:5a:0f:5a:d8:a9:95:b2:ba:30:15: . . . [omitted for brevity] . . . 5b:ca:9c:7c:19:48:77:1e:5d prime2: 00:cd:82:da:84:71:1d:18:52:cb:c6:4d:74:14:be: . . . [omitted for brevity] . . . 5f:db:d5:5e:47:89:a7:ef:e3 exponent1: 32:37:62:f6:a6:bf:9c:91:d6:f0:12:c3:f7:04:e9: . . . [omitted for brevity] . . . 97:3e:33:31:89:66:64:d1 exponent2: 00:88:a2:e8:90:47:f8:75:34:8f:41:50:3b:ce:93: . . . [omitted for brevity] . . . ff:74:d4:be:f3:47:45:bd:cb coefficient: 4d:7c:09:4c:34:73:c4:26:f0:58:f5:e1:45:3c:af: . . . [omitted for brevity] . . . af:01:5f:af:ad:6a:09:bf Step 2: Sign the ELF File object By now you should have your private key, and obtained, by hook or crook, a cert (either from a CA or use one you created (a self-signed cert). The next step is to sign one or more objects with your private key and cert. Here's a simple example that creates an object file, signs, verifies, and lists the contents of the ELF signature. $ echo '#include <stdio.h>\nint main(){printf("Hello\\n");}'>hello.c $ make hello cc -o hello hello.c $ elfsign verify -v -c MYSELFSIGNED.pem -e hello elfsign: no signature found in hello. $ elfsign sign -F rsa_sha256 -v -k MYSELFSIGNED.key -c MYSELFSIGNED.pem -e hello elfsign: hello signed successfully. format: rsa_sha256. signer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com. signed on: October 17, 2013 04:22:49 PM PDT. $ elfsign list -f format -e hello rsa_sha256 $ elfsign list -f signer -e hello O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com $ elfsign list -f time -e hello October 17, 2013 04:22:49 PM PDT $ elfsign verify -v -c MYSELFSIGNED.key -e hello elfsign: verification of hello failed. format: rsa_sha256. signer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com. signed on: October 17, 2013 04:22:49 PM PDT. Signing using the pkcs11 keystore To sign the ELF file using a private key in the secure pkcs11 keystore, replace "-K MYSELFSIGNED.key" in the "elfsign sign" command line with "-T MYPRIVATEKEY", where MYPRIVATKEY is the pkcs11 token label. Step 3: Install the cert and test on another system Just signing the object isn't enough. You need to copy or install the cert and the signed ELF file(s) on another system to test that the signature is OK. Your public key cert should be installed in /etc/certs. Use elfsign verify to verify the signature. Elfsign verify checks each cert in /etc/certs until it finds one that matches the elfsign signature in the file. If one isn't found, the verification fails. Here's an example: $ su Password: # rm /etc/certs/MYSELFSIGNED.key # cp MYSELFSIGNED.pem /etc/certs # exit $ elfsign verify -v hello elfsign: verification of hello passed. format: rsa_sha256. signer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com. signed on: October 17, 2013 04:24:20 PM PDT. After testing, package your cert along with your ELF object to allow elfsign verification after your cert and object are installed or copied. Under the Hood: elfsign verification Here's the steps taken to verify a ELF file signed with elfsign. The steps to sign the file are similar except the private key exponent is used instead of the public key exponent and the .SUNW_signature section is written to the ELF file instead of being read from the file. Generate a digest (SHA-256) of the ELF file sections. This digest uses all ELF sections loaded in memory, but excludes the ELF header, the .SUNW_signature section, and the symbol table Extract the RSA signature (RSA-2048) from the .SUNW_signature section Extract the RSA public key modulus and public key exponent (65537) from the public key cert Calculate the expected digest as follows:     signaturepublicKeyExponent % publicKeyModulus Strip the PKCS#1 padding (most significant bytes) from the above. The padding is 0x00, 0x01, 0xff, 0xff, . . ., 0xff, 0x00. If the actual digest == expected digest, the ELF file is verified (OK). Further Information elfsign(1), pktool(1), and openssl(1) man pages. "Signed Solaris 10 Binaries?" blog by Darren Moffat (2005) shows how to use elfsign. "Simple CLI based CA on Solaris" blog by Darren Moffat (2008) shows how to set up a simple CA for use with self-signed certificates. "How to Create a Certificate by Using the pktool gencert Command" System Administration Guide: Security Services (available at docs.oracle.com)

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  • Class design issue

    - by user2865206
    I'm new to OOP and a lot of times I become stumped in situations similar to this example: Task: Generate an XML document that contains information about a person. Assume the information is readily available in a database. Here is an example of the structure: <Person> <Name>John Doe</Name> <Age>21</Age> <Address> <Street>100 Main St.</Street> <City>Sylvania</City> <State>OH</State> </Address> <Relatives> <Parents> <Mother> <Name>Jane Doe</Name> </Mother> <Father> <Name>John Doe Sr.</Name> </Father> </Parents> <Siblings> <Brother> <Name>Jeff Doe</Name> </Brother> <Brother> <Name>Steven Doe</Name> </Brother> </Siblings> </Relatives> </Person> Ok lets create a class for each tag (ie: Person, Name, Age, Address) Lets assume each class is only responsible for itself and the elements directly contained Each class will know (have defined by default) the classes that are directly contained within them Each class will have a process() function that will add itself and its childeren to the XML document we are creating When a child is drawn, as in the previous line, we will have them call process() as well Now we are in a recursive loop where each object draws their childeren until all are drawn But what if only some of the tags need to be drawn, and the rest are optional? Some are optional based on if the data exists (if we have it, we must draw it), and some are optional based on the preferences of the user generating the document How do we make sure each object has the data it needs to draw itself and it's childeren? We can pass down a massive array through every object, but that seems shitty doesnt it? We could have each object query the database for it, but thats a lot of queries, and how does it know what it's query is? What if we want to get rid of a tag later? There is no way to reference them. I've been thinking about this for 20 hours now. I feel like I am misunderstanding a design principle or am just approaching this all wrong. How would you go about programming something like this? I suppose this problem could apply to any senario where there are classes that create other classes, but the classes created need information to run. How do I get the information to them in a way that doesn't seem fucky? Thanks for all of your time, this has been kicking my ass.

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  • Lifetime issue of IDisposable unmanaged resources in a complex object graph?

    - by stakx
    This question is about dealing with unmanaged resources (COM interop) and making sure there won't be any resource leaks. I'd appreciate feedback on whether I seem to do things the right way. Background: Let's say I've got two classes: A class LimitedComResource which is a wrapper around a COM object (received via some API). There can only be a limited number of those COM objects, therefore my class implements the IDisposable interface which will be responsible for releasing a COM object when it's no longer needed. Objects of another type ManagedObject are temporarily created to perform some work on a LimitedComResource. They are not IDisposable. To summarize the above in a diagram, my classes might look like this: +---------------+ +--------------------+ | ManagedObject | <>------> | LimitedComResource | +---------------+ +--------------------+ | o IDisposable (I'll provide example code for these two classes in just a moment.) Question: Since my temporary ManagedObject objects are not disposable, I obviously have no control over how long they'll be around. However, in the meantime I might have Disposed the LimitedComObject that a ManagedObject is referring to. How can I make sure that a ManagedObject won't access a LimitedComResource that's no longer there? +---------------+ +--------------------+ | managedObject | <>------> | (dead object) | +---------------+ +--------------------+ I've currently implemented this with a mix of weak references and a flag in LimitedResource which signals whether an object has already been disposed. Is there any better way? Example code (what I've currently got): LimitedComResource: class LimitedComResource : IDisposable { private readonly IUnknown comObject; // <-- set in constructor ... void Dispose(bool notFromFinalizer) { if (!this.isDisposed) { Marshal.FinalReleaseComObject(comObject); } this.isDisposed = true; } internal bool isDisposed = false; } ManagedObject: class ManagedObject { private readonly WeakReference limitedComResource; // <-- set in constructor ... public void DoSomeWork() { if (!limitedComResource.IsAlive()) { throw new ObjectDisposedException(); // ^^^^^^^^^^^^^^^^^^^^^^^ // is there a more suitable exception class? } var ur = (LimitedComResource)limitedComResource.Target; if (ur.isDisposed) { throw new ObjectDisposedException(); } ... // <-- do something sensible here! } }

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  • What makes the availability of both primitive and object-wrapped values in JavaScript useful?

    - by Delan Azabani
    I wrote a blog post a while ago detailing how the availability of both primitive and object-wrapped value types in JavaScript (for things such as Number, String and Boolean) causes trouble, including but not limited to type-casting to a boolean (e.g. object-wrapped NaN, "" and false actually type-cast to true). My question is, with all this confusion and problems, is there any benefit to JavaScript having both types of values for the built-in classes?

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  • Object Building in ActionScript

    - by kumar
    I am getting an object structure like Object-- --- Object STRING1:VALUE STRING2:VALUE STRING3:VALUE ---- OBJECT STRING1:VALUE STRING2:VALUE STRING3:VALUE Now I want to filter this object because i need only STRING2:VALUE in the same object structure and need to a an structure similar to: Object STRING2:VALUE Object STRING2:VALUE and I need to do it in runtime can somebody please let me know ..

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  • Detect when a new property is added to a Javascript object?

    - by UICodes
    A simple example using a built-in javascript object: navigator.my_new_property = "some value"; //can we detect that this new property was added? I don't want to constantly poll the object to check for new properties. Is there some type of higher level setter for objects instead of explicitly stating the property to monitor? Again, I don't want to detect if the property value changed, but rather when a new property is added. Ideas? thanks

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  • Android: canvas.drawBitmap with Orientation(MagnetField)Sensor

    - by user368374
    hallo, i am developing Android app with orientation sensor. now i got problem. What i want to do is, change scale and position of bitmap which read from sd card. The scale and position depend on value from orientation sensor. i use canvas.drawBitmap(), then it cause problem. the app is just shut down. other drawXXX()methods have no problem..any suggestion? public class AnMagImgtestActivity extends Activity implements SensorEventListener { private SensorManager sensorManager; private MySurfaceView view; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); sensorManager = (SensorManager)getSystemService(SENSOR_SERVICE); view = new MySurfaceView(this); ///make it fullscreen getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN); requestWindowFeature(Window.FEATURE_NO_TITLE); ///give screen a hiropon getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON); setContentView(view); } @Override protected void onResume() { super.onResume(); List sensors = sensorManager.getSensorList(Sensor.TYPE_ORIENTATION); if (sensors.size() 0) { Sensor sensor = sensors.get(0); sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_GAME); } } @Override protected void onPause() { super.onPause(); sensorManager.unregisterListener(this); } @Override public void onAccuracyChanged(Sensor sensor, int accuracy) { } @Override public void onSensorChanged(SensorEvent event) { view.onValueChanged(event.values); } class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback{ public MySurfaceView(Context context) { super(context); getHolder().addCallback(this); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { onValueChanged(new float[3]); } @Override public void surfaceCreated(SurfaceHolder holder) { } @Override public void surfaceDestroyed(SurfaceHolder holder) { } void onValueChanged(float[] values) { Canvas canvas = getHolder().lockCanvas(); //String imgfn = "/sdcard/seekcamera"+"/"+regcode+"/to"+"/"+tempnum+".jpg"; String imgfn = "/sdcard/seekcamera"+"/de"+"/to"+"1.jpg"; //String imgfn = "/sdcard/seekcamera"+"/00"+"/00"+"/"+"42.jpg"; File mf = new File(imgfn); Bitmap bitmap0 = BitmapFactory.decodeFile(mf.getPath()); if (canvas != null) { Paint paint = new Paint(); paint.setAntiAlias(true); paint.setColor(Color.GREEN); paint.setTextSize(12); canvas.drawColor(Color.BLACK); paint.setAlpha(200); for (int i = 0; i < values.length; i++) { canvas.drawText("values[" + i + "]: " + values[i], 0, paint.getTextSize() * (i + 1), paint); } paint.setColor(Color.WHITE); paint.setTextSize(100+values[2]); paint.setAlpha( (int) (255-values[2])); canvas.drawText("Germany", values[0]*1+20, paint.getTextSize() * 1+values[2]-80, paint); ///here is the problem.. canvas.drawBitmap(bitmap0, values[0],values[1], paint); getHolder().unlockCanvasAndPost(canvas); } } } }

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  • Looping through a SimpleXML object, or turning the whole thing into an array.

    - by Coffee Cup
    I'm trying to work out how to iterate though a returned SimpleXML object. I'm using a toolkit called Tarzan AWS, which connects to Amazon Web Services (SimpleDB, S3, EC2, etc). I'm specifically using SimpleDB. I can put data into the Amazon SimpleDB service, and I can get it back. I just don't know how to handle the SimpleXML object that is returned. The Tarzan AWS documentation says this: Look at the response to navigate through the headers and body of the response. Note that this is an object, not an array, and that the body is a SimpleXML object. Here's a sample of the returned SimpleXML object: [body] = SimpleXMLElement Object ( [QueryWithAttributesResult] = SimpleXMLElement Object ( [Item] = Array ( [0] = SimpleXMLElement Object ( [Name] = message12413344443260 [Attribute] = Array ( [0] = SimpleXMLElement Object ( [Name] = active [Value] = 1 ) [1] = SimpleXMLElement Object ( [Name] = user [Value] = john ) [2] = SimpleXMLElement Object ( [Name] = message [Value] = This is a message. ) [3] = SimpleXMLElement Object ( [Name] = time [Value] = 1241334444 ) [4] = SimpleXMLElement Object ( [Name] = id [Value] = 12413344443260 ) [5] = SimpleXMLElement Object ( [Name] = ip [Value] = 10.10.10.1 ) ) ) [1] = SimpleXMLElement Object ( [Name] = message12413346907303 [Attribute] = Array ( [0] = SimpleXMLElement Object ( [Name] = active [Value] = 1 ) [1] = SimpleXMLElement Object ( [Name] = user [Value] = fred ) [2] = SimpleXMLElement Object ( [Name] = message [Value] = This is another message ) [3] = SimpleXMLElement Object ( [Name] = time [Value] = 1241334690 ) [4] = SimpleXMLElement Object ( [Name] = id [Value] = 12413346907303 ) [5] = SimpleXMLElement Object ( [Name] = ip [Value] = 10.10.10.2 ) ) ) ) So what code do I need to get through each of the object items? I'd like to loop through each of them and handle it like a returned mySQL query. For example, I can query SimpleDB and then loop though the SimpleXML so I can display the results on the page. Alternatively, how do you turn the whole shebang into an array? I'm new to SimpleXML, so I apologise if my questions aren't specific enough.

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  • C# using the "this" keyword in this situation?

    - by Alex
    Hi, I've completed a OOP course assignment where I design and code a Complex Number class. For extra credit, I can do the following: Add two complex numbers. The function will take one complex number object as a parameter and return a complex number object. When adding two complex numbers, the real part of the calling object is added to the real part of the complex number object passed as a parameter, and the imaginary part of the calling object is added to the imaginary part of the complex number object passed as a parameter. Subtract two complex numbers. The function will take one complex number object as a parameter and return a complex number object. When subtracting two complex numbers, the real part of the complex number object passed as a parameter is subtracted from the real part of the calling object, and the imaginary part of the complex number object passed as a parameter is subtracted from the imaginary part of the calling object. I have coded this up, and I used the this keyword to denote the current instance of the class, the code for my add method is below, and my subtract method looks similar: public ComplexNumber Add(ComplexNumber c) { double realPartAdder = c.GetRealPart(); double complexPartAdder = c.GetComplexPart(); double realPartCaller = this.GetRealPart(); double complexPartCaller = this.GetComplexPart(); double finalRealPart = realPartCaller + realPartAdder; double finalComplexPart = complexPartCaller + complexPartAdder; ComplexNumber summedComplex = new ComplexNumber(finalRealPart, finalComplexPart); return summedComplex; } My question is: Did I do this correctly and with good style? (using the this keyword)?

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  • jQuery accessing objects

    - by user1275268
    I'm trying to access the values of an object from a function I created with a callback, but have run into some trouble. I'm still fairly new at jQuery/javascript. I call the function as follows: siteDeps(id,function(data){ $.each(data,function(key,val) { console.log(key); console.log(val); }); }); The function runs 5 ajax queries from XML data and returns data as an multidimensional object; here is a excerpt showing the meat of it: function siteDeps(id,callback) { var result = { sitecontactid : {}, siteaddressid : {}, sitephoneid : {}, contactaddressid : {}, contactphoneid : {} }; ...//.... var url5 = decodeURIComponent("sql2xml.php?query=xxxxxxxxxxx"); $.get(url5, function(data){ $(data).find('ID').each(function(i){ result.delsitephoneid[i] = $(this).text(); }); }); callback(result); } The console.log output shows this: sitecontactid Object 0: "2" 1: "3" __proto__: Object siteaddressid Object 0: "1" __proto__: Object sitephoneid Object 0: "1" 1: "5" 2: "54" __proto__: Object contactaddressid Object 0: "80" __proto__: Object contactphoneid Object 0: "6" __proto__: Object How can I extract the callback data in a format I can use, for instance sitephoneid: "1","5","54" Or is there a better/simpler way to do this? Thanks in advance.

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  • Can static methods be called using object/instance in .NET

    Ans is Yes and No   Yes in C++, Java and VB.NET No in C#   This is only compiler restriction in c#. You might see in some websites that we can break this restriction using reflection and delegates, but we can’t, according to my little research J I shall try to explain you…   Following is code sample to break this rule using reflection, it seems that it is possible to call a static method using an object, p1 using System; namespace T {     class Program     {         static void Main()         {             var p1 = new Person() { Name = "Smith" };             typeof(Person).GetMethod("TestStatMethod").Invoke(p1, new object[] { });                     }         class Person         {             public string Name { get; set; }             public static void TestStatMethod()             {                 Console.WriteLine("Hello");             }         }     } } but I do not think so this method is being called using p1 rather Type Name “Person”. I shall try to prove this… look at another example…  Test2 has been inherited from Test1. Let’s see various scenarios… Scenario1 using System; namespace T {     class Program     {         static void Main()         {             Test1 t = new Test1();            typeof(Test2).GetMethod("Method1").Invoke(t,                                  new object[] { });         }     }     class Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method1");         }     }       class Test2 : Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method2");         }     } } Output:   At test1::Method2 Scenario2         static void Main()         {             Test2 t = new Test2();            typeof(Test2).GetMethod("Method1").Invoke(t,                                          new object[] { });         }   Output:   At test1::Method2   Scenario3         static void Main()         {             Test1 t = new Test2();            typeof(Test2).GetMethod("Method1").Invoke(t,                             new object[] { });         }   Output: At test1::Method2 In all above scenarios output is same, that means, Reflection also not considering the object what you pass to Invoke method in case of static methods. It is always considering the type which you specify in typeof(). So, what is the use passing instance to “Invoke”. Let see below sample using System; namespace T {     class Program     {         static void Main()         {            typeof(Test2).GetMethod("Method1").                Invoke(null, new object[] { });         }     }       class Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method1");         }     }     class Test2 : Test1     {         public static void Method1()         {             Console.WriteLine("At test1::Method2");         }     } }   Output is   At test1::Method2   I was able to call Invoke “Method1” of Test2 without any object.  Yes, there no wonder here as Method1 is static. So we may conclude that static methods cannot be called using instances (only in c#) Why Microsoft has restricted it in C#? Ans: Really there Is no use calling static methods using objects because static methods are stateless. but still Java and C++ latest compilers allow calling static methods using instances. Java sample class Test {      public static void main(String str[])      {            Person p = new Person();            System.out.println(p.GetCount());      } }   class Person {   public static int GetCount()   {      return 100;   } }   Output          100 span.fullpost {display:none;}

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  • Unity3d: calculate the result of a transform without modifying transform object itself

    - by Heisenbug
    I'm in the following situation: I need to move an object in some way, basically rotating it around its parent local position, or translating it in its parent local space (I know how to do this). The amount of rotation and translation is know at runtime (it depends on several factors, the speed of the object, enviroment factors, etc..). The problem is the following: I can perform this transformation only if the result position of the transformed object fit some criterias. An example could be this: the distance between the position before and after the transformation must be less than a given threshold. (Actually the conditions could be several and more complex) The problem is that if I use Transform.Rotate and Transform.Translate methods of my GameObject, I will loose the original Transform values. I think I can't copy the original Transform using instantiate for performance issues. How can I perform such a task? I think I have more or less 2 possibilities: First Don't modify the GameObject position through Transform. Calculate which will be the position after the transform. If the position is legal, modify transform through Translate and Rotate methods Second Store the original transform someway. Transform the object using Translate and Rotate. If the transformed position is illegal, restore the original one.

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  • How to write constructors which might fail to properly instantiate an object

    - by whitman
    Sometimes you need to write a constructor which can fail. For instance, say I want to instantiate an object with a file path, something like obj = new Object("/home/user/foo_file") As long as the path points to an appropriate file everything's fine. But if the string is not a valid path things should break. But how? You could: 1. throw an exception 2. return null object (if your programming language allows constructors to return values) 3. return a valid object but with a flag indicating that its path wasn't set properly (ugh) 4. others? I assume that the "best practices" of various programming languages would implement this differently. For instance I think ObjC prefers (2). But (2) would be impossible to implement in C++ where constructors must have void as a return type. In that case I take it that (1) is used. In your programming language of choice can you show how you'd handle this problem and explain why?

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  • Object pools for efficient resource management

    - by GameDevEnthusiast
    How can I avoid using default new() to create each object? My previous demo had very unpleasant framerate hiccups during dynamic memory allocations (usually, when arrays are resized), and creating lots of small objects which often contain one pointer to some DirectX resource seems like an awful lot of waste. I'm thinking about: Creating a master look-up table to refer to objects by handles (for safety & ease of serialization), much like EntityList in source engine Creating a templated object pool, which will store items contiguously (more cache-friendly, fast iteration, etc.) and the stored elements will be accessed (by external systems) via the global lookup table. The object pool will use the swap-with-last trick for fast removal (it will invoke the object's ~destructor first) and will update the corresponding indices in the global table accordingly (when growing/shrinking/moving elements). The elements will be copied via plain memcpy(). Is it a good idea? Will it be safe to store objects of non-POD types (e.g. pointers, vtable) in such containers? Related post: Dynamic Memory Allocation and Memory Management

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  • Scrolling though objects then creating a new instace of this object

    - by gopgop
    In my game when pressing the right mouse button you will place an object on the ground. all objects have the same super class (GameObject). I have a field called selected and will be equal to one certain gameobject at a time. when clicking the right mouse button it checks whats the instance of selected and that how it determines which object to place on the ground. code exapmle: t is the "slot" for which the object will go to. if (selected instanceof MapleTree) { t = new MapleTree(game,highLight); } else if (selected instanceof OakTree) { t = new OakTree(game,highLight); } Now it has to be a "new" instance of the object. Eventually my game will have hundreds of GameObjects and I don't want to have a huge if else statement. How would I make it so it scrolls though the possible kinds of objects and if its the correct type then create a new instance of it...? When pressing E it will switch the type of selected and is an if else statement as well. How would I do it for this too? here is a code example: if (selected instanceof MapleTree) { selected = new OakTree(game); } else if (selected instanceof OakTree) { selected = new MapleTree(game); }

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  • Draw contour around object in Opengl

    - by Maciekp
    I need to draw contour around 2d objects in 3d space. I tried drawing lines around object(+points to fill the gap), but due to line width, some part of it(~50%) was covering object. I tried to use stencil buffer, to eliminate this problem, but I got sth like this(contour is green): http://goo.gl/OI5uc (sorry I can't post images, due to my reputation) You can see(where arrow points), that some parts of line are behind object, and some are above. This changes when I move camera, but always there is some part, that is covering it. Here is code, that I use for drawing object: glColorMask(1,1,1,1); std::list<CObjectOnScene*>::iterator objIter=ptr->objects.begin(),objEnd=ptr->objects.end(); int countStencilBit=1; while(objIter!=objEnd) { glColorMask(1,1,1,1); glStencilFunc(GL_ALWAYS,countStencilBit,countStencilBit); glStencilOp(GL_REPLACE,GL_KEEP,GL_REPLACE ); (*objIter)->DrawYourVertices(); glStencilFunc(GL_NOTEQUAL,countStencilBit,countStencilBit); glStencilOp(GL_KEEP,GL_KEEP,GL_REPLACE); (*objIter)->DrawYourBorder(); ++objIter; ++countStencilBit; } I've tried different settings of stencil buffer, but always I was getting sth like that. Here is question: 1.Am I setting stencil buffer wrong? 2. Are there any other simple ways to create contour on such objects? Thanks in advance.

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  • [EF + Oracle]Object Context

    - by JTorrecilla
    Prologue After EF episodes I and II, we are going to see the Object Context. What is Object Context? It is a class which manages the DB connection, and the different Entities of our model. When Visual Studio creates the EF model, like I explain previously, also generates a Class that extends ObjectContext. ObjectContext provides: - DB connection - Add, update and delete functions. - Object Sets of Entities. - State of Pending Changes. This class will give a function, for each Entity, like  Esta clase va a contar con una función, para cada entidad, del tipo “AddTo{ENTITY}({Entity_Type } value)”, which are going to add a Entity to the related ObjectSet. In addition, it has a property, for each Entity, like “ObjectSet<TEntity> Entity”, does will keep the related record set. It will be filled with the CreateObjectSet<TEntity> function of Base class (ObjectContext). What is an ObjectSet? It is a class that allows us to manage the Entity Set from a Type. It inherits from: · ObjectQuery<TEntity> · IObjectSet<TEntity> · IQueryAble<TEntity · IEnumerable<TEntity · IQueryAble · IEnumerable An ObjectSet is a class property that allows query, insert, delete and update records from a determinate Entity. In following chapters we will see how to query Entities. LazyLoadingEnabled A very important property of the Context is “LazyLoadingEnabled”. This Boolean property lets indicate if the data loading is lazy, in other words, the Object will not be created and query until not be needed. Finally In this post we have seen what the VS generated context is, some of the characteristics, and where to see Entity data. In next chapters we will see, CRUD operations, and how to query ObjectSets.

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  • COM Object Method Invoke Exception - Silverlight 4

    - by Adam Driscoll
    I'm trying to use the new AutomationFactory provided with Silverlight 4 to call a .NET COM class. .NET COM-Exposed Class: public class ObjectContainer { public bool GetObject([Out, MarshalAs((UnmanagedType.IUnknown)] out object obj) { obj = new SomeOtherObj(); return true; } } Silverlight Assembly: dynamic objectContainer; try { objectContainer = AutomationFactory.GetObject(ProgId); } catch { objectContainer = AutomationFactory.CreateObject(ProgId); } object obj; if (!objectContainer.GetObject(out obj)) { throw new Exception(); } When I call objectContainer.GetObject(out obj) an exception is thrown stating: Value does not fall within the expected range. at MS.Internal.ComAutomation.ComAutomationNative.CheckInvokeHResult(UInt32 hr, String memberName, String exceptionSource, String exceptionDescription, String exceptionHelpFile, UInt32 exceptionHelpContext) at MS.Internal.ComAutomation.ComAutomationNative.Invoke(Boolean tryInvoke, String memberName, ComAutomationInvokeType invokeType, ComAutomationInteropValue[] rgParams, IntPtr nativePeer, ComAutomationInteropValue& returnValue) at MS.Internal.ComAutomation.ComAutomationObject.InvokeImpl(Boolean tryInvoke, String name, ComAutomationInvokeType invokeType, Object& returnValue, Object[] args) at MS.Internal.ComAutomation.ComAutomationObject.Invoke(String name, ComAutomationInvokeType invokeType, Object[] args) at System.Runtime.InteropServices.Automation.AutomationMetaObjectProvider.TryInvokeMember(InvokeMemberBinder binder, Object[] args, Object& result) at System.Runtime.InteropServices.Automation.AutomationMetaObjectProviderBase.<.cctorb__4(Object obj, InvokeMemberBinder binder, Object[] args) at CallSite.Target(Closure , CallSite , Object , String , Object& ) at CallSite.Target(Closure , CallSite , Object , String , Object& ) at ApplicationModule.ObjectContainer.GetObject() Wha's the deal?

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  • Object oriented design of game in Java: How to handle a party of NPCs?

    - by Arvanem
    Hi folks, I'm making a very simple 2D RPG in Java. My goal is to do this in as simple code as possible. Stripped down to basics, my class structure at the moment is like this: Physical objects have an x and y dimension. Roaming objects are physical objects that can move(). Humanoid objects are roaming objects that have inventories of GameItems. The Player is a singleton humanoid object that can hire up to 4 NPC Humanoids to join his or her party, and do other actions, such as fight non-humanoid objects. NPC Humanoids can be hired by the Player object to join his or her party, and once hired can fight for the Player. So far I have given the Player class a "party" ArrayList of NPC Humanoids, and the NPC Humanoids class a "hired" Boolean. However, my fight method is clunky, using an if to check the party size before implementing combat, e.g. public class Player extends Humanoids { private ArrayList<Humanoids> party; // GETTERS AND SETTERS for party here //... public void fightEnemy(Enemy eneObj) { if (this.getParty().size() == 0) // Do combat without party issues else if (this.getParty().size() == 1) // Do combat with party of 1 else if (this.getParty().size() == 2) // Do combat with party of 2 // etc. My question is, thinking in object oriented design, am I on the right track to do this in as simple code as possible? Is there a better way?

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