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  • Py_INCREF/DECREF: When

    - by Izz ad-Din Ruhulessin
    Is one correct in stating the following: If a Python object is created in a C function, but the function doesn't return it, no INCREF is needed, but a DECREF is. [false]If the function does return it, you do need to INCREF, in the function that receives the return value.[/false] When assigning C typed variables as attributes, like double, int etc., to the Python object, no INCREF or DECREF is needed. Assigning Python objects as attributes to your other Python objects goes like this: PyObject *foo; foo = bar // A Python object tmp = self->foo; Py_INCREF(foo); self->foo = foo; Py_XDECREF(tmp); //taken from the manual, but it is unclear if this works in every situation EDIT: -- can I safely use this in every situation? (haven't run into one where it caused me problems) dealloc of a Python object needs to DECREF for every other Python object that it has as an attribute, but not for attributes that are C types. Edit With 'C type as an attribute I mean bar and baz: typedef struct { PyObject_HEAD PyObject *foo; int bar; double baz; } FooBarBaz;

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  • URL development and mod_rewrite

    - by iRector
    My site is made-up of the main page, and multiple sub-directories, all under the same domain. My URLS are currently like .................| Ideal clean version: mysite.com mysite.com/?content=content1 ......................| mysite.com/content1/ mysite.com/?content=content2&page=4 ........| mysite.com/content2/4/ mysite.com/?content=content3 ......................| mysite.com/content3/ mysite.com/?content=content4 ......................| mysite.com/content4/ mysite.com/?content=article&id=34 ............| mysite.com/article/34/ Then the sub-directories are essentially the same: mysite.com/subdir, mysite.com/subdir2, mysite.com/subdir3, etc mysite.com/subdir/?content=content1 ...................| mysite.com/subdir/content1/ mysite.com/subdir/?content=content2&page=4 .....| mysite.com/subdir/content2/4/ mysite.com/subdir/?content=content3 ...................| mysite.com/subdir/content3/ mysite.com/subdir/?content=content4 ...................| mysite.com/subdir/content4/ mysite.com/subdir/?content=article&id=34 .........| mysite.com/subdir/article/34/ I've used mod_rewrite briefly, but I'm not sure how to approach these multiple variables. Also, how would I differentiate between the actually subfolders, and the content variable. As so to prevent 'subdir' or 'subdir2' from being plugged in as the content variable for the root site. I've played around with plenty of code snippets, but I've wiped my .htaccess slate clean, and approach you all in an attempt to help me repopulate it. Your input would thoroughly be appreciated. Note: The only time the page query string will be needed is when 'content' == 'content2' ?content=content2&page=4 **Same rule is shared by the article/id relationship, all other 'content' values are expected to be dynamic.

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  • Multiple ajax request and progress bar

    - by hunt
    Hi, In a following piece of code i am create a progress bar and showing its progress as the ajax request get processed. i am faking the progress shown here just by adding 5 in to cnt counter variable after that i made a check when counter reach to 90. at this point if the request is not executed successfully then i will pause/disable the progress bar and whenever response come i will complete the whole progress bar with 100. now the problem is i want to add multiple progress bar as i am firing multiple ajax request. so following is the code to implement only for one request and one progress bar but i want it for more than one. as global variables are used over here for checking response and timer id so i don't know how well i can handle it for multiple request var cnt=0; var res=null; function getProgress(data){ res=data; } var i =0; $('#start').click(function(){ i = setInterval(function() { if(res!=null) { clearInterval(i); $("#pb1").progressbar( "option", "value", cnt=cnt+100 ); } var value = $("#pb1").progressbar("option", "value"); if(value >=90 && res==null){ $("#pb1").progressbar("option", "disable"); } else{ $("#pb1").progressbar( "option", "value", cnt=cnt+5 ); } },2500); $.ajax({ url: 'http://localhost/beta/demo.php', success: getProgress }); }); $("#pb1").progressbar({ value: 0 , change: function(event, ui) { if(res!=null) clearInterval(i); } });

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  • zend session exception on zend_session::start with forms

    - by Grant Collins
    Hi I'm having issues with trying to use Zend_Form_SubForm and sessions. My controller is in essance acting a wizard showing different subforms depending on the stage of the wizard. Using the example I am planning on storing the forms in a session namespace. My controller looks like this. include 'mylib/Form/addTaskWizardForm.php'; class AddtaskController extends Zend_Controller_Action{ private $config = null; private $log = null; private $subFormSession = null; /** * This function is called and initialises the global variables to this object * which is the configuration details and the logger to write to the log file. */ public function init(){ $this->config = Zend_Registry::getInstance()->get('config'); $this->log = Zend_Registry::getInstance()->get('log'); //set layout $this->_helper->layout->setLayout('no-sidemenus'); //we need to get the subforms and $wizardForms = new addTaskWizardForm(); $this->subFormSession = new Zend_Session_Namespace('addTaskWizardForms'); if(!isset($this->subFormSession->subforms)){ $this->subFormSession->subforms = $wizardForms; } } /** * The Landing page controller for the site. */ public function indexAction(){ $form = $this->subFormSession->subforms->getSubForm('start'); $this->view->form = $form; } However this is causing the application session to crash out with Uncaught exception 'Zend_Session_Exception' with message 'Zend_Session::start() Any idea why this is having issues with the Zend Session?? thanks.

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  • pass a number value to a Timer, XML and AS3

    - by VideoDnd
    I want to pass a number value to a Timer. How do I do this? My number and integer values for other variables work fine. Error I get null object reference and coercion of value, because I'm not passing to 'timer' properly. I don't want to say my variable's a number, I want to say it has a number value. Variable //what I have now var timer:Timer; timer = new Timer(100); Path myXML.COUNT.text(); XML <?xml version="1.0" encoding="utf-8"?> <SESSION> <TIMER TITLE="speed">100</TIMER> </SESSION> Parse and Load //LOAD XML var myXML:XML; var myLoader:URLLoader = new URLLoader(); myLoader.load(new URLRequest("time.xml")); myLoader.addEventListener(Event.COMPLETE, processXML); //PARSE XML function processXML(e:Event):void { myXML = new XML(e.target.data);

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  • Mmap and structure

    - by blid..pl
    I'm working some code including communication between processes, using semaphores. I made structure like this: typedef struct container { sem_t resource, mutex; int counter; } container; and use in that way (in main app and the same in subordinate processes) container *memory; shm_unlink("MYSHM"); //just in case fd = shm_open("MYSHM", O_RDWR|O_CREAT|O_EXCL, 0); if(fd == -1) { printf("Error"); exit(EXIT_FAILURE); } memory = mmap(NULL, sizeof(container), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); ftruncate(fd, sizeof(container)); Everything is fine when I use one of the sem_ functions, but when I try to do something like memory->counter = 5; It doesn't work. Probably I got something wrong with pointers, but I tried almost everything and nothing seems to work. Maybe there's a better way to share variables, structures etc between processes ? Unfortunately I'm not allowed to use boost or something similiar, the code is for educational purposes and I'm intentend to keep as simple as it's possible.

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  • Calc_Anniversary Function with a Loop

    - by Rachel Ann Arndt
    Name: Calc_Anniversary Input: Pay_Date, Hire_Date, Termination_Date Output: "Y" if is the anniversary of the employee's Hire_Date, "N" if it is not, and "T" if he has been terminated before his anniversary. Description: Create local variables to hold the month and day of the employee's Date_of_Hire, Termination_Date, and of the processing date using the TO_CHAR function. First check to see if he was terminated before his anniversary. The anniversary could be on any day during the pay period, so there will be a loop to check all 14 days in the pay period to see if one was his anniversary. CREATE OR replace FUNCTION Calc_anniversary( incoming_anniversary_date IN VARCHAR2) RETURN BOOLEAN IS hiredate VARCHAR2(20); terminationdate VARCHAR(20); employeeid VARCHAR2(38); paydate NUMBER := 0; BEGIN SELECT Count(arndt_raw_time_sheet_data.pay_date) INTO paydate FROM arndt_raw_time_sheet_data; WHILE paydate <= 14 LOOP SELECT To_char(employee_id, '999'), To_char(hire_date, 'DD-MON'), To_char(termination_date, 'DD-MON') INTO employeeid, hiredate, terminationdate FROM employees, time_sheet WHERE employees.employee_id = time_sheet.employee_id AND paydate = pay_date; IF terminationdate > hiredate THEN RETURN 'T'; ELSE IF To_char(SYSDATE, 'DD-MON') = To_char(hiredate, 'DD-MON')THEN RETURN 'Y'; ELSE RETURN 'N'; END IF; END IF; paydate := paydate + 1; END LOOP; END; I need help with the loop..

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  • translate a PHP $string using google translator API

    - by Toni Michel Caubet
    hey there! been google'ing for a while how is the best way to translate with google translator in PHP, found very different ways converting URLS, or using Js but i want to do it only with php (or with a very simple solution JS/JQUery) example: //hopefully with $from_lan and $to_lan being like 'en','de', .. or similar function translate($from_lan, $to_lan, $text){ // do return $translated_text; } can you give me a clue? or maybe you already have this function.. my intention it's to use it only for the languages i have not already defined (or keys i haven't defined), that's why i wan it so simple, will be only temporal.. EDIT thanks for your replies we are now trying this soulutions: function auto_translate($from_lan, $to_lan, $text){ // do $json = json_decode(file_get_contents('https://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q=' . urlencode($text) . '&langpair=' . $from_lan . '|' . $to_lan)); $translated_text = $json->responseData->translatedText; return $translated_text; } (there was a extra 'g' on variables for lang... anyway) it returns: works now :) i don't really understand much the function, so any idea why is not acepting the object? (now i do) OR: unction auto_translate($from_lan, $to_lan, $text){ // do // $json = json_decode(file_get_contents('https://ajax.googleapis.com/ajax/services/language/translate?v=1.0&q=' . urlencode($text) . '&langpair=' . $from_lan . '|' . $to_lan)); // $translated_text = $json['responseData']['translatedText']; error_reporting(1); require_once('GTranslate.php'); try{ $gt = new Gtranslate(); $translated_text = $gt-english_to_german($text); } catch (GTranslateException $ge) { $translated_text= $ge->getMessage(); } return $translated_text; } And this one looks great but it doesn't even gives me an error, the page won't load (error_report(1) :S) thanks in advance!

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  • jQuery attribute question

    - by Nick Simone
    I'm trying to select a series of divs one at a time. I'm sure theres a better way to do this, but I gave them all unique rels and I'm using the rels to select them one at a time. I want to move them over the width of the div, then animate it dropping down the screen. What I have is: $(document).ready(function(){ var totalbricks = 7; var index = 2; $(".brick").animate({top:"600px"}); while(index < totalbricks) { var postion = 45*index; $(".brick[rel='+index+']").css('left', postion+'px'); $(".brick[rel='+index+']").animate({top:"600px"}); index++; } }); All the divs are in a container div. Jquery docs say, 'Variables can be used using the following syntax: [name='" +MyVar+ "']' What am I doing wrong? Here is the HTML that is being used by the jQuery <body> <div id="container"> <div id="canvas"> <div class="brick" rel="1"> </div> <div class="brick" rel="2"> </div> <div class="brick" rel="3"> </div> <div class="brick" rel="4"> </div> <div class="brick" rel="5"> </div> <div class="brick" rel="6"> </div> <div class="brick" rel="7"> </div> </div> </div> </body>

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  • Change classloader

    - by Chris
    I'm trying to switch the class loader at runtime: public class Test { public static void main(String[] args) throws Exception { final InjectingClassLoader classLoader = new InjectingClassLoader(); Thread.currentThread().setContextClassLoader(classLoader); Thread thread = new Thread("test") { public void run() { System.out.println("running..."); // approach 1 ClassLoader cl = TestProxy.class.getClassLoader(); try { Class c = classLoader.loadClass("classloader.TestProxy"); Object o = c.newInstance(); c.getMethod("test", new Class[] {}).invoke(o); } catch (Exception e) { e.printStackTrace(); } // approach 2 new TestProxy().test(); }; }; thread.setContextClassLoader(classLoader); thread.start(); } } and: public class TestProxy { public void test() { ClassLoader tcl = Thread.currentThread().getContextClassLoader(); ClassLoader ccl = ClassToLoad.class.getClassLoader(); ClassToLoad classToLoad = new ClassToLoad(); } } (it is not relevant what the InjectingClassLoader is) I'd like to make the result of "approach 1" and "approach 2" exactly same, but it looks like thread.setContextClassLoader(classLoader) does nothing and the "approach 2" always uses the system classloader (can be determined by comparing tcl and ccl variables while debugging). Is it possible to make all classes loaded by new thread use given classloader?

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  • C++ ofstream cannot write to file....

    - by user69514
    Hey I am trying to write some numbers to a file, but when I open the file it is empty. Can you help me out here? Thanks. /** main function **/ int main(){ /** variables **/ RandGen* random_generator = new RandGen; int random_numbers; string file_name; /** ask user for quantity of random number to produce **/ cout << "How many random number would you like to create?" << endl; cin >> random_numbers; /** ask user for the name of the file to store the numbers **/ cout << "Enter name of file to store random number" << endl; cin >> file_name; /** now create array to store the number **/ int random_array [random_numbers]; /** file the array with random integers **/ for(int i=0; i<random_numbers; i++){ random_array[i] = random_generator -> randInt(-20, 20); cout << random_array[i] << endl; } /** open file and write contents of random array **/ const char* file = file_name.c_str(); ofstream File(file); /** write contents to the file **/ for(int i=0; i<random_numbers; i++){ File << random_array[i] << endl; } /** close the file **/ File.close(); return 0; /** END OF PROGRAM **/ }

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  • Create a model that switches between two different states using Temporal Logic?

    - by NLed
    Im trying to design a model that can manage different requests for different water sources. Platform : MAC OSX, using latest Python with TuLip module installed. For example, Definitions : Two water sources : w1 and w2 3 different requests : r1,r2,and r3 - Specifications : Water 1 (w1) is preferred, but w2 will be used if w1 unavailable. Water 2 is only used if w1 is depleted. r1 has the maximum priority. If all entities request simultaneously, r1's supply must not fall below 50%. - The water sources are not discrete but rather continuous, this will increase the difficulty of creating the model. I can do a crude discretization for the water levels but I prefer finding a model for the continuous state first. So how do I start doing that ? Some of my thoughts : Create a matrix W where w1,w2 ? W Create a matrix R where r1,r2,r3 ? R or leave all variables singular without putting them in a matrix I'm not an expert in coding so that's why I need help. Not sure what is the best way to start tackling this problem. I am only interested in the model, or a code sample of how can this be put together. edit Now imagine I do a crude discretization of the water sources to have w1=[0...4] and w2=[0...4] for 0, 25, 50, 75,100 percent respectively. == means implies Usage of water sources : if w1[0]==w2[4] -- meaning if water source 1 has 0%, then use 100% of water source 2 etc if w1[1]==w2[3] if w1[2]==w2[2] if w1[3]==w2[1] if w1[4]==w2[0] r1=r2=r3=[0,1] -- 0 means request OFF and 1 means request ON Now what model can be designed that will give each request 100% water depending on the values of w1 and w2 (w1 and w2 values are uncontrollable so cannot define specific value, but 0...4 is used for simplicity )

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  • Dynamically add data stored in php to nested json

    - by HoGo
    I am trying to dynamicaly generate data in json for jQuery gantt chart. I know PHP but am totally green with JavaScript. I have read dozen of solutions on how dynamicaly add data to json, and tried few dozens of combinations and nothing. Here is the json format: var data = [{ name: "Sprint 0", desc: "Analysis", values: [{ from: "/Date(1320192000000)/", to: "/Date(1322401600000)/", label: "Requirement Gathering", customClass: "ganttRed" }] },{ name: " ", desc: "Scoping", values: [{ from: "/Date(1322611200000)/", to: "/Date(1323302400000)/", label: "Scoping", customClass: "ganttRed" }] }, <!-- Somoe more data--> }]; now I have all data in php db result. Here it goes: $rows=$db->fetchAllRows($result); $rowsNum=count($rows); And this is how I wanted to create json out of it: var data=''; <?php foreach ($rows as $row){ ?> data['name']="<?php echo $row['name'];?>"; data['desc']="<?php echo $row['desc'];?>"; data['values'] = {"from" : "/Date(<?php echo $row['from'];?>)/", "to" : "/Date(<?php echo $row['to'];?>)/", "label" : "<?php echo $row['label'];?>", "customClass" : "ganttOrange"}; } However this does not work. I have tried without loop and replacing php variables with plain text just to check, but it did not work either. Displays chart without added items. If I add new item by adding it to the list of values, it works. So there is no problem with the Gantt itself or paths. Based on all above I assume the problem is with adding plain data to json. Can anyone please help me to fix it?

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  • Struts2 Converting Enum Array fills array with single null value

    - by Kyle Partridge
    For a simple action class with these member variables: ... private TestConverterEnum test; private TestConverterEnum[] tests; private List<TestConverterEnum> tList; ... And a simple enum: public enum TestConverterEnum { A, B, C; } Using the default struts2 enum conversion, when I send the request like so: TestConterter.action?test=&tests=&tList=&b=asdf For test I get a null value, which is expected. For the Array and List, however, I get and Array (or list) with one null element. Is this what is expected? Is there a way to prevent this. We recently upgraded our struts2 version, and we had our own converters, which also don't work in this case, so I was hoping to use the default conversion method. We already have code that is validating these arrays for null and length, and I don't want to have to add another condition to these branches. Is there a way to prevent this bevavior?

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  • JSLINT error: Move all 'var' declarations to the top of the function.

    - by Oleg Yaroshevych
    JSLINT site updated, and I cannot check JS scripts anymore. For me, this warning is not critical, and I don't want to go through thousands of lines to fix this, I want to find more critical problems. Does anybody know how to turn off this error, or use legacy JSLINT? UPDATE Example: function doSomethingWithNodes(nodes){ this.doSomething(); for (var i = 0; i < nodes.length; ++i){ this.doSomethingElse(nodes[i]); } doSomething(); // want to find this problem } jslint.com output: Error: Problem at line 4 character 8: Move all 'var' declarations to the top of the function. for (var i = 0; i < nodes.length; ++i){ Problem at line 4 character 8: Stopping, unable to continue. (44% scanned). Problem: Having variables on top of the functions is new requirement. I cannot use JSLINT to test code, because it stops scanning script on this error. I have a lot of code, and do not want to threat this warning as critical error.

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  • When NOT TO USE 'this' keyword?

    - by LifeH2O
    Sorry for asking it again, there are already 3 questions about this keyword. But all of them tell the purpose of 'this'. My question is when not to use 'this' keyword . OR Is it all right to use this keyword always in situation like the code class RssReader { private XmlTextReader _rssReader; private XmlDocument _rssDoc; private XmlNodeList _xn; protected XmlNodeList Item { get { return _xn; } } public int Count { get { return _count; } } public bool FetchFeed(String url) { this._rssReader = new XmlTextReader(url); this._rssDoc = new XmlDocument(); _rssDoc.Load(_rssReader); _xn = _rssDoc.SelectNodes("/rss/channel/item"); _count = _xn.Count; return true; } } here i have not used 'this' with "_xn" and "_count" also not with "_rssDoc.Load(_rssReader);" is it fine? Should i use "this" with all occurrences of class variables within the class?

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  • How can I find out if the MainActivity is being paused from my Java class?

    - by quinestor
    I am using motion sensor detection in my application. My design is this: a class gets the sensor services references from the main activity and then it implements SensorEventListener. That is, the MainActivity does not listen for sensor event changes: public void onCreate(Bundle savedInstanceState) { // ... code mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE); mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); // The following is my java class, it does not extends any android fragment/activty mShakeUtil = new ShakeUtil(mSensorManager,mAccelerometer,this); // ..more code.. } I can't redesign ShakeUtil so it is a fragment nor activity, unfortunately. Now to illustrate the problem consider: MainActivity is on its way to be destroyed/paused. I.e screen rotation ShakeUtil's onSensorChanged(SensorEvent event) gets called in the process.. One of the things that happen inside onSensorChanged is a dialog interaction, which gives the error: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState When the previous happens between MainActivity's onSaveInstanceState and onPause. I know this can be prevented if I successfully detect that MainActivity is being pause in ShakeUtil. How can I detect that MainActivity is being paused or onSaveInstanceState was called from ShakeUtil? Alternatively, how can I avoid this issue without making Shakeutil extend activity? So far I have tried with flag variables but that isn't good enough, I guess these are not atomic operations. I tried using Activity's isChangingConfigurations(), but I get an undocummented "NoSuchMethodFound" error.. I am unregistering the sensors by calling ShakeUtil when onPause in main ACtivity

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  • Interface vs Abstract Class (general OO)

    - by Kave
    Hi, I have had recently two telephone interviews where I've been asked about the differences between an Interface and an Abstract class. I have explained every aspect of them I could think of, but it seems they are waiting for me to mention something specific, and I dont know what it is. From my experience I think the following is true, if i am missing a major point please let me know: Interface: Every single Method declared in an Interface will have to be implemented in the subclass. Only Events, Delegates, Properties (C#) and Methods can exist in a Interface. A class can implement multiple Interfaces. Abstract Class Only Abstract methods have to be implemented by the subclass. An Abstract class can have normal methods with implementations. Abstract class can also have class variables beside Events, Delegates, Properties and Methods. A class can only implement one abstract class only due non-existence of Multi-inheritance in C#. 1) After all that the interviewer came up with the question What if you had an Abstract class with only abstract methods, how would that be different from an interface? I didnt know the answer but I think its the inheritance as mentioned above right? 2) An another interviewer asked me what if you had a Public variable inside the interface, how would that be different than in Abstract Class? I insisted you can't have a public variable inside an interface. I didn't know what he wanted to hear but he wasn't satisfied either. Many Thanks for clarification, Kave See Also: When to use an interface instead of an abstract class and vice versa Interfaces vs. Abstract Classes How do you decide between using an Abstract Class and an Interface?

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  • PAYPAL IPN Response Problem

    - by Gorkem Tolan
    I am having a problem with Paypal IPN response. After payment is made by the customer, paypal ipn returns this url www.mywebsite.com?orderid=32&tx=2AC67201DL3533325&st=Pending&amt=2.50&cc=USD&cm=&item_number=32 There are a couple of issues 1- Postback field names are undefined or missing. Thus I can get the INVALID message. I am not sure if my website does not read POST variables. When I looked at IPN history, it shows that each IPN has been sent with the complete url. 2- Payment status keeps coming Pending. Does this issue cause the first issue? Thank you for your responses in advance. Here is the code: Dim strSandbox As String, strLive As String Dim req As HttpWebRequest strSandbox = "http://www.sandbox.paypal.com/cgi-bin/webscr/" strLive = "https://www.paypal.com/cgi-bin/webscr" req = CType(WebRequest.Create(strSandbox), HttpWebRequest) 'Set values for the request back req.Method = "POST" req.ContentType = "application/x-www-form-urlencoded" Dim param() As Byte param = Request.BinaryRead(HttpContext.Current.Request.ContentLength) Dim strRequest As String strRequest = Encoding.ASCII.GetString(param) strRequest = strRequest & "&cmd=_notify-validate" req.ContentLength = strRequest.Length 'Response.Write(strRequest) 'Send the request to PayPal and get the response Dim streamOut As StreamWriter streamOut = New StreamWriter(req.GetRequestStream(), System.Text.Encoding.ASCII) streamOut.Write(strRequest) streamOut.Close() Dim streamIn As StreamReader streamIn = New StreamReader(req.GetResponse().GetResponseStream()) Dim strResponse As String strResponse = streamIn.ReadToEnd() Response.Write(strResponse) streamIn.Close() If (strResponse = "VERIFIED") Then Response.Redirect("thankyou.aspx") ElseIf (strResponse = "INVALID") Then End If

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  • floating point equality in Python and in general

    - by eric.frederich
    I have a piece of code that behaves differently depending on whether I go through a dictionary to get conversion factors or whether I use them directly. The following piece of code will print 1.0 == 1.0 -> False But if you replace factors[units_from] with 10.0 and factors[units_to ] with 1.0 / 2.54 it will print 1.0 == 1.0 -> True #!/usr/bin/env python base = 'cm' factors = { 'cm' : 1.0, 'mm' : 10.0, 'm' : 0.01, 'km' : 1.0e-5, 'in' : 1.0 / 2.54, 'ft' : 1.0 / 2.54 / 12.0, 'yd' : 1.0 / 2.54 / 12.0 / 3.0, 'mile' : 1.0 / 2.54 / 12.0 / 5280, 'lightyear' : 1.0 / 2.54 / 12.0 / 5280 / 5.87849981e12, } # convert 25.4 mm to inches val = 25.4 units_from = 'mm' units_to = 'in' base_value = val / factors[units_from] ret = base_value * factors[units_to ] print ret, '==', 1.0, '->', ret == 1.0 Let me first say that I am pretty sure what is going on here. I have seen it before in C, just never in Python but since Python in implemented in C we're seeing it. I know that floating point numbers will change values going from a CPU register to cache and back. I know that comparing what should be two equal variables will return false if one of them was paged out while the other stayed resident in a register. Questions What is the best way to avoid problems like this?... In Python or in general. Am I doing something completely wrong? Side Note This is obviously part of a stripped down example but what I'm trying to do is come with with classes of length, volume, etc that can compare against other objects of the same class but with different units. Rhetorical Questions If this is a potentially dangerous problem since it makes programs behave in an undetermanistic matter, should compilers warn or error when they detect that you're checking equality of floats Should compilers support an option to replace all float equality checks with a 'close enough' function? Do compilers already do this and I just can't find the information.

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  • 'Fixed' for loop - what is more efficient?

    - by pimvdb
    I'm creating a tic-tac-toe game, and one of the functions has to iterate through each of the 9 fields (tic-tac-toe is played on a 3x3 grid). I was wondering what is more efficient (which one is perhaps faster, or what is the preferred way of scripting in such situation) - using two for nested loops like this: for(var i=0; i<3; i++) { for(var j=0; j<3; j++) { checkField(i, j); } } or hard-coding it like this: checkField(0, 0); checkField(0, 1); checkField(0, 2); checkField(1, 0); checkField(1, 1); checkField(1, 2); checkField(2, 0); checkField(2, 1); checkField(2, 2); As there are only 9 combinations, it would be perhaps overkill to use two nested for loops, but then again this is clearer to read. The for loop, however, will increment variables and check whether i and j are smaller than 3 every time as well. In this example, the time saving at least might be negligible, but what is the preferred way of coding in this case? Thanks.

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  • Strange behavior with Javascript's __defineSetter__

    - by Shea Barton
    I have a large project in which I need to intercept assignments to things like element.src, element.href, element.style, etc. I figured out to do this with defineSetter, but it is behaving very strangely (using Chrome 8.0.552.231) An example: var attribs = ["href", "src", "background", "action", "onblur", "style", "onchange", "onclick", "ondblclick", "onerror", "onfocus", "onkeydown", "onkeypress", "onkeyup", "onmousedown", "onmousemove", "onmouseover", "onmouseup", "onresize", "onselect", "onunload"]; for(a = 0; a < attribs.length; a++) { var attrib_name = attribs[a]; var func = new Function("attrib_value", "this.setAttribute(\"" + attrib_name + "\", attrib_value.toUpperCase());"); HTMLElement.prototype.__defineSetter__(attrib_name, func); } What this code should do is whenever common element attribute in attribs is assigned, it uses setAttribute() to set a uppercased version of that attribute. For some very strange reason, the setter works for only ~1/3 of the assignments. For example with element.src = "test" the new src is "TEST", like it should be however with element.href = "test" the new href is "test", not uppercase then even when I try element.__lookupSetter__("href"), it returns the proper, uppercasing setter the strangest thing is different variables are intercepted properly between Chrome and Firefox help!!

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  • How is a functional programming-based javascript app laid out?

    - by user321521
    I've been working with node.js for awhile on a chat app (I know, very original, but I figured it'd be a good learning project). Underscore.js provides a lot of functional programming concepts which look interesting, so I'd like to understand how a functional program in javascript would be setup. From my understanding of functional programming (which may be wrong), the whole idea is to avoid side effects, which are basically having a function which updates another variable outside of the function so something like var external; function foo() { external = 'bar'; } foo(); would be creating a side effect, correct? So as a general rule, you want to avoid disturbing variables in the global scope. Ok, so how does that work when you're dealing with objects and what not? For example, a lot of times, I'll have a constructor and an init method that initializes the object, like so: var Foo = function(initVars) { this.init(initVars); } Foo.prototype.init = function(initVars) { this.bar1 = initVars['bar1']; this.bar2 = initVars['bar2']; //.... } var myFoo = new Foo({'bar1': '1', 'bar2': '2'}); So my init method is intentionally causing side effects, but what would be a functional way to handle the same sort of situation? Also, if anyone could point me to either a python or javascript source code of a program that tries to be as functional as possible, that would also be much appreciated. I feel like I'm close to "getting it", but I'm just not quite there. Mainly I'm interested in how functional programming works with traditional OOP classes concept (or does away with it for something different if that's the case).

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  • How do you refactor a large messy codebase?

    - by Ricket
    I have a big mess of code. Admittedly, I wrote it myself - a year ago. It's not well commented but it's not very complicated either, so I can understand it -- just not well enough to know where to start as far as refactoring it. I violated every rule that I have read about over the past year. There are classes with multiple responsibilities, there are indirect accesses (I forget the technical term - something like foo.bar.doSomething()), and like I said it is not well commented. On top of that, it's the beginnings of a game, so the graphics is coupled with the data, or the places where I tried to decouple graphics and data, I made the data public in order for the graphics to be able to access the data it needs... It's a huge mess! Where do I start? How would you start on something like this? My current approach is to take variables and switch them to private and then refactor the pieces that break, but that doesn't seem to be enough. Please suggest other strategies for wading through this mess and turning it into something clean so that I can continue where I left off!

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  • Assign sage variable values into R objects via sagetex and Sweave

    - by sheed03
    I am writing a short Sweave document that outputs into a Beamer presentation, in which I am using the sagetex package to solve an equation for two parameters in the beta binomial distribution, and I need to assign the parameter values into the R session so I can do additional processing on those values. The following code excerpt shows how I am interacting with sage: <<echo=false,results=hide>>= mean.raw <- c(5, 3.5, 2) theta <- 0.5 var.raw <- mean.raw + ((mean.raw^2)/theta) @ \begin{frame}[fragile] \frametitle{Test of Sage 2} \begin{sagesilent} var('a1, b1, a2, b2, a3, b3') eqn1 = [1000*a1/(a1+b1)==\Sexpr{mean.raw[1]}, ((1000*a1*b1)*(1000+a1+b1))/((a1+b1)^2*(a1+b1+1))==\Sexpr{var.raw[1]}] eqn2 = [1000*a2/(a2+b2)==\Sexpr{mean.raw[2]}, ((1000*a2*b2)*(1000+a2+b2))/((a2+b2)^2*(a2+b2+1))==\Sexpr{var.raw[2]}] eqn3 = [1000*a3/(a3+b3)==\Sexpr{mean.raw[3]}, ((1000*a3*b3)*(1000+a3+b3))/((a3+b3)^2*(a3+b3+1))==\Sexpr{var.raw[3]}] s1 = solve(eqn1, a1,b1) s2 = solve(eqn2, a2,b2) s3 = solve(eqn3, a3,b3) \end{sagesilent} Solutions of Beta Binomial Parameters: \begin{itemize} \item $\sage{s1[0]}$ \item $\sage{s2[0]}$ \item $\sage{s3[0]}$ \end{itemize} \end{frame} Everything compiles just fine, and in that slide I am able to see the solutions to the three equations respective parameters in that itemized list (for example the first item in the itemized list from that beamer slide is outputted as [a1=(328/667), b1=(65272/667)] (I am not able to post an image of the beamer slide but I hope you get the idea). I would like to save the parameter values a1,b1,a2,b2,a3,b3 into R objects so that I can use them in simulations. I cannot find any documentation in the sagetex package on how to save output from sage commands into variables for use with other programs (in this case R). Any suggestions on how to get these values into R?

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