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• wget crawling search results of news website

  - by kiltek

  I am trying to crawl the search results of a news website using wget. The name of the website is www.voanews.com. After typing in my search keyword and clicking search, it proceeds to the results. Then i can specify a "to" and a "from"-date and hit search again. After this the URL becomes: http://www.voanews.com/search/?st=article&k=mykeyword&df=10%2F01%2F2013&dt=09%2F20%2F2013&ob=dt#article and the actual content of the results is what i want to download. To achieve this I created the following wget-command: wget --reject=js,txt,gif,jpeg,jpg \ --accept=html \ --user-agent=My-Browser \ --recursive --level=2 \ www.voanews.com/search/?st=article&k=germany&df=08%2F21%2F2013&dt=09%2F20%2F2013&ob=dt#article Unfortunately, the crawler doesn't download the search results. It only gets into the upper link bar, which contains the "Home,USA,Africa,Asia,..." links and saves the articles they link to. It seems like he crawler doesn't check the search result links at all. What am I doing wrong and how can I modify the wget command to download the results search list links (and of course the sites they link to) only ?

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• Cannot access Class methods from previous windows form - C#

  - by George

  I am writing an app, still, where I need to test some devices every minute for 30 minutes. It made sense to use a timer set to kick off every 60 secs and do whats required in the event handler. However, I need the app to wait for the 30 mins until I have finished with the timer since the following code alters the state of the devices I am trying to monitor. I obviously don't want to use any form of loop to do this. I thought of using another windows form, since I also display the progress, which will simply kick off the timer and wait until its complete. The problem I am having with this is that I use a device Class and cant seem to get access to the methods in the device class from the 2nd (3rd actually - see below) windows form. I have an initial windows form where I get input from the user, then call the 2nd windows form where it work out which tests need to be done and which device classes need to be used, and then I want to call the 3rd windows form to handle the timer. I will have up to 6-7 device classes and so wanted to only instantiate them when actually requiring them, from the 2nd form. Should I have put this logic into the 1st windows form (program class ??) ? Would I not still have the problem of not being able to access device class methods from there too ? Anyway, perhaps someone knows of a better way to do the checks every minute without the rest of the code executing (and changing the status of the devices) or how I should be accessing the methods in the app ?? Well that's the problem, I cant get that part of it to work correctly. Here is the definition for the calling form including the device class - namespace NdtStart { public partial class fclsNDTCalib : Form { NDTClass NDT = new NDTClass(); public fclsNDTCalib() (new fclsNDTTicker(NDT)).ShowDialog(); Here is the class def for the called form - namespace NdtStart { public partial class fclsNDTTicker : Form { public fclsNDTTicker() I tried lots but couldn't get the arguments to work.

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• Is it important to dispose SolidBrush and Pen?

  - by Joe

  I recently came across this VerticalLabel control on CodeProject. I notice that the OnPaint method creates but doesn't dispose Pen and SolidBrush objects. Does this matter, and if so how can I demonstrate whatever problems it can cause? EDIT This isn't a question about the IDisposable pattern in general. I understand that callers should normally call Dispose on any class that implements IDisposable. What I want to know is what problems (if any) can be expected when GDI+ object are not disposed as in the above example. It's clear that, in the linked example, OnPaint may be called many times before the garbage collector kicks in, so there's the potential to run out of handles. However I suspect that GDI+ internally reuses handles in some circumstances (for example if you use a pen of a specific color from the Pens class, it is cached and reused). What I'm trying to understand is whether code like that in the linked example will be able to get away with neglecting to call Dispose. And if not, to see a sample that demonstrated what problems it can cause. I should add that I have very often (including the OnPaint documentation on MSDN) seen WinForms code samples that fail to dispose GDI+ objects.

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• Javascript Callback when variable is set to X

  - by Erik

  Hey everyone, Have an issue I can't seem to wrap my head around. I'm wanting to write a generic javascript function that will accept a variable and a callback, and continue to execute until that variable is something other than false. For example, the variable SpeedFeed.user.sid is false until something else happens in the code, but I don't want to execute a particular callback until it has been set. The call: SpeedFeed.helper_ready(SpeedFeed.user.sid, function(){ alert(SpeedFeed.user.sid); // Run function that requires sid to be set. }); The function: helper_ready: function(vtrue, callback){ if(vtrue != false){ callback(); } else { setTimeout(function(){ SpeedFeed.helper_ready(vtrue, callback); }, SpeedFeed.apiCheckTime); } } The issue I've narrowed it down to appears to be that because in the setTimeout I call vtrue instead of the actual SpeedFeed.user.sid, it's going to be set to false always. I realize I could write a specific function for each time that just evaluates the SpeedFeed.user.sid, but I'd like to have a generic method that I could use throughout the application. Thanks for any insight :)

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• Windows FTP batch sript to read & dl from external user list

  - by Will Sims

  i have several old, unused batches that i'm redoing.. I have a batch file for an old network arch from several years ago.. the main thing I'd like it to do now is read a list of files.. I'll explain the setup.. Server updates a complete list [CurrentMediaStores.txt] 2x a day. The laptops can set settings to DL this list through their start.bat which also runs addins and updates I aply to my pc's, to give my batches and myself a break from slavish folder assignments and add a lil more dynamics and less adminin the bats now call on a list the user makes by simply copying a line from the CMS.txt file and pasting it into their [Grab_List.txt] My problem is though I have the branch :: off right now and the code that detects if LAN is connected or not to switch to an ftp connection. I'd like for the ftp batch to call/ use the Grab_List also. but I just can't/ don't know how to pass and do the for loop with a ftp session to loop through x amount of files in the users req list.. Anyhelp would be greatly appreciated

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• Working with Decimal fields in SSIS

  - by CoffeeAddict

  I'm using SQL Server 2008 w/SP2. I've got an incoming decimal(9,2) field incoming through my OLE DB transformation to my recordset destination transformation. It's like it's reading it as something other than a decimal? I don't know..I'm not an SSIS guru. So continuing on...the problem I have starts here with me trying to stuff the value into a variable for this decimal field. In a foreach loop, I have a variable to represent this decimal field so I can work with it. The first problem that I believe is pretty well known is SSIS variables do not have a decimal type. And from my own testing and what I've read out there, people are using type object for the variable to make SSIS "happy" with decimal values? It makes mine happy. But, then in my foreach loop, I have a for loop. And inside that I'm using an E*xecute SQL Task transformation*. In it, I need to create a parameter mapping to my variable so I can work with that decimal field in my T-SQL call in here. So now I see a type decimal for the parameter and use it and set that to point to my variable. When I run SSIS and it hits my SQL call, I get this in my output window.: The type is not supported.DBTYPE_DECIMAL So I am hitting a wall here. All I wanna do is work with a decimal!!!

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• Python C API from C++ app - know when to lock

  - by Alex

  Hi Everyone, I am trying to write a C++ class that calls Python methods of a class that does some I/O operations (file, stdout) at once. The problem I have ran into is that my class is called from different threads: sometimes main thread, sometimes different others. Obviously I tried to apply the approach for Python calls in multi-threaded native applications. Basically everything starts from PyEval_AcquireLock and PyEval_ReleaseLock or just global locks. According to the documentation here when a thread is already locked a deadlock ensues. When my class is called from the main thread or other one that blocks Python execution I have a deadlock. Python Cfunc1() - C++ func that creates threads internally which lead to calls in "my class", It stuck on PyEval_AcquireLock, obviously the Python is already locked, i.e. waiting for C++ Cfunc1 call to complete... It completes fine if I omit those locks. Also it completes fine when Python interpreter is ready for the next user command, i.e. when thread is calling funcs in the background - not inside of a native call I am looking for a workaround. I need to distinguish whether or not the global lock is allowed, i.e. Python is not locked and ready to receive the next command... I tried PyGIL_Ensure, unfortunately I see hang. Any known API or solution for this ? (Python 2.4)

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• c# delegate and abstract class

  - by BeraCim

  Hi all: I currently have 2 concrete methods in 2 abstract classes. One class contains the current method, while the other contains the legacy method. E.g. // Class #1 public abstract class ClassCurrent<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllRootNodes(int i) { //some code } } // Class #2 public abstract class MyClassLegacy<T> : BaseClass<T> where T : BaseNode, new() { public List<T> GetAllLeafNodes(int j) { //some code } } I want the corresponding method to run in their relative scenarios in the app. I'm planning to write a delegate to handle this. The idea is that I can just call the delegate and write logic in it to handle which method to call depending on which class/project it is called from (at least thats what I think delegates are for and how they are used). However, I have some questions on that topic (after some googling): 1) Is it possible to have a delegate that knows the 2 (or more) methods that reside in different classes? 2) Is it possible to make a delegate that spawns off abstract classes (like from the above code)? (My guess is a no, since delegates create concrete implementation of the passed-in classes) 3) I tried to write a delegate for the above code. But I'm being technically challenged: public delegate List GetAllNodesDelegate(int k); GetAllNodesDelegate del = new GetAllNodesDelegate(ClassCurrent.GetAllRootNodes); I got the following error: An object reference is required for the non-static field, method, property ClassCurrent<BaseNode>.GetAllRootNodes(int) I might have misunderstood something... but if I have to manually declare a delegate at the calling class, AND to pass in the function manually as above, then I'm starting to question whether delegate is a good way to handle my problem. Thanks.

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• jQuery Ajax load images problem

  - by jackysee

  I have a code that would call $.load() to get an HTML fragment. In the fragment there will be a list of images and a script that would do some calculation based on the list size. The fragment looks like <div> <ul> <li><img .../></li> <li><img .../></li> ... </ul> </div> <script> //... script to do calculation on the list width </script> Originally, I use css's max-width to ensure that the image would not exceed 180px. But as IE has no max-width, I use the expression hack. However, it seems when the image are first load, the script cannot get a correct width of image list. Seems like the script load earlier than the CSS expression. If it is a new page, I can certainly call $(window).load() to ensure all the images are loaded. But what can I do in an ajax html fragment request?

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• I'm trying to build a query to search against a fulltext index in mysql

  - by Rockinelle

  The table's schema is pretty simple. I have a child table that stores a customer's information like address and phone number. The columns are user_id, fieldname, fieldvalue and fieldname. So each row will hold one item like phone number, address or email. This is to allow an unlimited number of each type of information for each customer. The people on the phones need to look up these customers quickly as they call into our call center. I have experimented with using LIKE% and I'm working with a FULLTEXT index now. My queries work, but I want to make them more useful because if someone searches for a telephone area code like 805 that will bring up many people, and then they add the name Bill to narrow it down, '805 Bill'. It will show EVERY customer that has 805 OR Bill. I want it to do AND searches across multiple rows within each customer. Currently I'm using the query below to grab the user_ids and later I do another query to fetch all the details for each user to build their complete record. SELECT DISTINCT `user_id` FROM `user_details` WHERE MATCH (`fieldvalue`) AGAINST ('805 Bill') Again, I want to do the above query against groups of rows that belong to a single user, but those users have to match the search keywords. What should I do?

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• parse xml with elementtree, custom sorting

  - by microspace

  I want to parse xml file in utf-8 and sort it by some field. Soring is made by custom alphabet (s1 from sourcecode). History of question is here: sorting of list containing utf-8 charachters. I've found how to sort xml here. Sorting work correctly, the problem is with elementtree, I must admit that it doesn't work on python3 Here is source code: #!/usr/bin/env python # -*- coding: utf-8 -*- #import xml.etree.ElementTree as ET # Python 2.5 import elementtree.ElementTree as ET s1='aáàAâÂbBcCçÇdDeéEfFgGgGhHiIîÎíiiIjJkKlLmMnNóoOöÖpPqQrRsSsStTuUûúÛüÜvVwWxXyYzZ' s2='11111122334455666aabbccddeeeeeeffgghhiijjkklllllmmnnooppqqrrsssssttuuvvwwxxyy' trans = str.maketrans(s1, s2) def unikey(seq): return seq[0].translate(trans) tree = ET.parse("tosort.xml") container = tree.find("entries") data = [] for elem in container: keyd = elem.findtext("k") data.append((keyd, elem)) print (data) data.sort(key=unikey) print (data) container[:] = [item[-1] for item in data] tree.write("sorted.xml", encoding="utf-8") Here are instructions to import elementtree module. When I import module this way :import xml.etree.ElementTree as ET, I get a message: Traceback (most recent call last): File "pcs.py", line 19, in <module> container[:] = [item[-1] for item in data] File "/usr/lib/python3.1/xml/etree/ElementTree.py", line 210, in __setitem__ assert iselement(element) AssertionError When I use this method to import: import elementtree.ElementTree as ET, I get this message: Traceback (most recent call last): File "pcs.py", line 4, in <module> import elementtree.ElementTree as ET File "/usr/local/lib/python3.1/dist-packages/elementtree/ElementTree.py", line 794, in <module> _escape = re.compile(eval(r'u"[&<>\"\u0080-\uffff]+"')) File "<string>", line 1 u"[&<>\"\u0080-\uffff]+" ^ SyntaxError: invalid syntax I use Python 3.1.3 (r313:86834, Nov 28 2010, 11:28:10). In python2.6 elementtree work without a problem. Content of tosort.xml: <xdxf> <entries> <ar><k>zaaaa</k>definition1</ar> <ar><k>saaaa</k>definition2</ar> ... ... </entries> </xdxf>

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• Loading Jscript files into Firefox extension

  - by colon3l

  Hi ! Let's get directly to the problem : I'm actually doing a firefox extension in which i would like to implement the jWebsocket API in order to build a small chat. I got my main script file, named test.js, and the jWebsocket lib into a js folder. Just for you to know, this is my first firefox extension ever. So in my XUL file I got this (for the script part only of course, the interface code is not shown) : <overlay id="test-overlay" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> <script type="application/x-javascript" src="chrome://test/content/test.js" /> <script type="application/x-javascript" src="chrome://test/content/js/jwebsocket.js" /> jwebsocket.js being the file I need to call according to jWebsocket website. In my main script file test.js I start with : if (jws.browserSupportsWebSockets()) { jWebSocketClient = new jws.jWebSocketJSONClient(); } else { var lMsg = jws.MSG_WS_NOT_SUPPORTED; alert(lMsg); } jws being the namespace created into the jwebsocket.js file. Of course I've got the required stand-alone server running in background, and working. So from what I understood looking on various websites, is that if a js file is loaded into the javascript allocated memory space (with the tag), all namespace/function should be available between each file. But this was mostly for HTML-oriented issues, so I'm not sure if it applies to XUL/Firefox environment. But the script keep failing at the first jws call. Any ideas on what goes wrong here ? I'm stuck for 2 days now :/

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• How to get resultset with stored procedure calls over two linked servers?

  - by räph

  I have problems filling a temporary table with the resultset from a procedure call on a linked server, in which again a procedure on another server is called. I have a Stored Procedure sproc1 with the following code, which calls another procedure sproc2 on a linked server. SET @sqlCommand = 'INSERT INTO #tblTemp ( ModuleID, ParamID) ' + '( SELECT * FROM OPENQUERY(' + @targetServer + ', ' + '''SET FMTONLY OFF; EXEC ' + @targetDB + '.usr.sproc2 ' + @param + ''' ) )' exec ( @sqlCommand ) Now in the called sproc2 I again call a third procedure sproc3 on another linked server, which returns my resultset. SET @sqlCommand = 'EXEC ' + @targetServer +'.database.usr.sproc3 ' + @param exec ( @sqlCommand ) The whole thing doen't work, as I get an SQL error 7391 The operation could not be performed because OLE DB provider "%ls" for linked server "%ls" was unable to begin a distributed transaction. I already checked the hints at this microsoft article, but without success. But maybe, I can change the code in sproc1. Would there be some alternative to the temp table and the open query? Just calling stored procedures from server A to B to C and returning the resultset is working (I do this often in the application). But this special case with the temp table and openquery doesn't work! Or is it just not possible what I am trying to do? The microsft article states: Check the object you refer on the destination server. If it is a view or a stored procedure, or causes an execution of a trigger, check whether it implicitly references another server. If so, the third server is the source of the problem. Run the query directly on the third server. If you cannot run the query directly on the third server, the problem is not actually with the linked server query. Resolve the underlying problem first. Is this my case? PS: I can't avoid the architecture with the three servers.

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• How do I implement a listener pattern over RMI using Spring?

  - by predhme

  So here is a generalized version of our application desgin: @Controller public class MyController { @Autowired private MyServiceInterface myServiceInterface; @RequestMapping("/myURL") public @ResponseBody String doSomething() { MyListenerInterface listener = new MyListenerInterfaceImpl(); myServiceInterface.doThenCallListener(listener); // do post stuff } } public interface MyListenerInterface { public void callA(); public void callB(); } public class MyListenerInterfaceImpl implements MyListenerInterface { // ... omitted for clarity } public interface MyServiceInterface { public void doThenCallListener(MyListenerInterface listener); } public class MyServiceImpl { public void doThenCallListener(MyListenerInterface listener) { // do stuff listener.callA(); } } Basically I have a controller that is being called via AJAX in which I am looking to return a response as a string. However, I need to make a call to the backend (MyServiceInterface). That guy is exposed through RMI by using Spring (man that was easy). But the service method as described requires a listener to be registered for invokation completion purposes. So what I assume I need to achieve is transparently to the backend make it so that when the listener methods are called, really the call is going over RMI. I would have thought Spring would have a simple way to wrap a POJO (not a service singleton) with RMI calls. I looked through their documentation but they had nothing besides exposing services via RMI. Could someone point me in the right direction?

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• Opening port 80 with Java application on Ubuntu

  - by Featheast

  What I need to do is running a Java application which is a RESTful service server side writtern by Restlet. And this service will be called by another app running on Google App Engine. Because of the restriction of GAE, every http call is limited to port 80 and 443 (http and https) with HttpUrlConnection class. As a result, I have to deploy my server side application on port 80 or 443. However, because the app is running on Ubuntu, and those ports under 1024 cannot be accessed by non-root user, then a Access Denied exception will be thrown when I run my app. The solutions that have come into my mind includs: Changing the security policy of JRE, which is the files resides in /lib/security/java.policy, to grantjava.net.SocketPermission "*.80" "listen, connect, accept, resolve" permission?However, neither using command line to include this file or overrides the content in JRE's java.policy file, the same exception keeps coming out. try to login as a root user, however because my unfamiliarity with Unix, I don't know how to do it. another solution I haven't try is to map all calls to 80 to a higher port like 1234, then I can deploy my app on 1234 without problem, and GAE call send request to port 80. But how to connect the missing gap is still a problem. Currently I am using a "hacking" method, which is to package the application into a jar file, and sudo running the jar file with root privilege. It works now, but definitely not appropriate in the real deployment environment. So if anyone have any idea about the solution, thanks very much!

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• c++ function scope

  - by Myx

  I have a main function in A.cpp which has the following relevant two lines of code: B definition(input_file); definition.Print(); In B.h I have the following relevant lines of code: class B { public: // Constructors B(void); B(const char *filename); ~B(void); // File input int ParseLSFile(const char *filename); // Debugging void Print(void); // Data int var1; double var2; vector<char* > var3; map<char*, vector<char* > > var4; } In B.cpp, I have the following function signatures (sorry for being redundant): B::B(void) : var1(-1), var2(numeric_limits<double>::infinity()) { } B::B(const char *filename) { B *def = new B(); def->ParseLSFile(filename); } B::~B(void) { // Free memory for var3 and var 4 } int B::ParseLSFile(const char *filename) { // assign var1, var2, var3, and var4 values } void B::Print(void) { // print contents of var1, var2, var3, and var4 to stdout } So when I call Print() from within B::ParseLSFile(...), then the contents of my structures print correctly to stdout. However, when I call definition.Print() from A.cpp, my structures are empty or contain garbage. Can anyone recommend the correct way to initialize/pass my structures so that I can access them outside of the scope of my function definition? Thanks.

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• Trying to find a PHP5 API-based embeddable CMS

  - by StrangeElement

  I've been making the rounds for a CMS that I can use as an API, in a sort of "embedded" mode. I mean by this that I don't want the CMS to do any logic or presentation. I want it to be used as an API, which I can then use within an existing site. I don't want to be tied to the architecture of the CMS. A good example of this is NC-CMS (http://www.nconsulting.ca/nc-cms/). All it needs is an include at the top, then wherever editable content is desired it's only a function call with a unique label. It's also perfect in the sense that it allows to differentiate between small strings (like titles, labels) and texts (which require a rich-text editor). It's the only CMS I found that fits this description, but it is a little too light as it does not handle site structure. I need to be able to allow my client to add pages, choosing an existing template for the layout. A minimal back-end is required. Wordpress also fits some requirements in that it handles only content editing and allows freedom for the themes by letting them call the content where and how they want it. But it is article-based and backwards, in that it embeds sites (as themes) within its structure, rather than being embeddable in sites like NC. It's funny how checking out all the CMS out there, almost all of them claim that most CMS are not self-sufficient, that they do not handle application logic, while (almost) every single on I found with only one exception do so. Many are mostly article-based blog engines, which does not fit my need. I would appreciate any CMS that fits the general description.

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• Why does this extension method throw a NullReferenceException in VB.NET?

  - by Dan

  From previous experience I had been under the impression that it's perfectly legal (though perhaps not advisable) to call extension methods on a null instance. So in C#, this code compiles and runs: // code in static class static bool IsNull(this object obj) { return obj == null; } // code elsewhere object x = null; bool exists = !x.IsNull(); However, I was just putting together a little suite of example code for the other members of my development team (we just upgraded to .NET 3.5 and I've been assigned the task of getting the team up to speed on some of the new features available to us), and I wrote what I thought was the VB.NET equivalent of the above code, only to discover that it actually throws a NullReferenceException. The code I wrote was this: ' code in module ' <Extension()> _ Function IsNull(ByVal obj As Object) As Boolean Return obj Is Nothing End Function ' code elsewhere ' Dim exampleObject As Object = Nothing Dim exists As Boolean = Not exampleObject.IsNull() The debugger stops right there, as if I'd called an instance method. Am I doing something wrong (e.g., is there some subtle difference in the way I defined the extension method between C# and VB.NET)? Is it actually not legal to call an extension method on a null instance in VB.NET, though it's legal in C#? (I would have thought this was a .NET thing as opposed to a language-specific thing, but perhaps I was wrong.) Can anybody explain this one to me?

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• Twitter O-Auth Callback url

  - by jtymann

  I am having a problem with Twitter's oauth authentication and using a callback url. I am coding in php and using the sample code referenced by the twitter wiki, http://github.com/abraham/twitteroauth I got that code, and tried a simple test and it worked nicely. However I want to programatically specify the callback url, and the example did not support that. So I quickly modified the getRequestToken() method to take in a parameter and now it looks like this: function getRequestToken($params = array()) { $r = $this->oAuthRequest($this->requestTokenURL(), $params); $token = $this->oAuthParseResponse($r); $this->token = new OAuthConsumer($token['oauth_token'], $token['oauth_token_secret']); return $token; } and my call looks like this $tok = $to->getRequestToken(array('oauth_callback' => 'http://127.0.0.1/twitter_prompt/index.php')); This is the only change I made, and the redirect works like a charm, however I am getting an error when I then try and use my newly granted access to try and make a call. I get a "Could not authenticate you" error. Also the application never actually gets added to the users authorized connections. Now I read the specs and I thought all I had to do was specify the parameter when getting the request token. Could someone a little more seasoned in oauth and twitter possibly give me a hand? Thank You

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• Correct Delphi compiler switches to stop in the user's code, not my component's

  - by Jeremy Mullin

  I'm modifying our VCL components so the end user's application links to our dcu files, instead of building our source code each time. We have everything working, but I want the debugger to stop on the user's code when an exception is raised. At first it would stop in our dcu and open the CPU window. I was able to prevent that by removing debug info from the dcu files. But now it still doesn't stop in the users code (like DevExpress libraries and others do). The following screencast is a short example. The first time I cause an exception in the DevExpress code, and the debugger correctly stops in my button event. The second time I cause an exception in my components, but the debugger doesn't have my button event on the call stack, and doesn't show me where the problem was. Any ideas why? http://screencast.com/t/NjhlOTRk Currently building the DCU's with these options: -$W+ -$D- -h -w -q Update: The TDataSet methods in between my component and the button event seem to cause this behavior. If I instead call a direct method of my table, I get the expected behavior. I'm guessing there isn't anything I can do about this, but I'm still curious why it happens.

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• Trouble with Unions in C program.

  - by Jordan S

  I am working on a C program that uses a Union. The union definition is in FILE_A header file and looks like this... // FILE_A.h**************************************************** xdata union { long position; char bytes[4]; }CurrentPosition; If I set the value of CurrentPosition.position in FILE_A.c and then call a function in FILE_B.c that uses the union, the data in the union is back to Zero. This is demonstrated below. // FILE_A.c**************************************************** int main.c(void) { CurrentPosition.position = 12345; SomeFunctionInFileB(); } // FILE_B.c**************************************************** void SomeFunctionInFileB(void) { // After the following lines execute I see all zeros in the flash memory. WriteByteToFlash(CurrentPosition.bytes[0]; WriteByteToFlash(CurrentPosition.bytes[1]; WriteByteToFlash(CurrentPosition.bytes[2]; WriteByteToFlash(CurrentPosition.bytes[3]; } Now, If I pass a long to SomeFunctionInFileB(long temp) and then store it into CurrentPosition.bytes within that function, and finally call WriteBytesToFlash(CurrentPosition.bytes[n]... it works just fine. It appears as though the CurrentPosition Union is not global. So I tried changing the union definition in the header file to include the extern keyword like this... extern xdata union { long position; char bytes[4]; }CurrentPosition; and then putting this in the source (.c) file... xdata union { long position; char bytes[4]; }CurrentPosition; but this causes a compile error that says: C:\SiLabs\Optec Programs\AgosRot\MotionControl.c:76: error 91: extern definition for 'CurrentPosition' mismatches with declaration. C:\SiLabs\Optec Programs\AgosRot\/MotionControl.h:48: error 177: previously defined here So what am I doing wrong? How do I make the union global?

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• ControlCollection extension method optimazation

  - by Johan Leino

  Hi, got question regarding an extension method that I have written that looks like this: public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance) where T : class { T control; foreach (Control ctrl in instance) { if ((control = ctrl as T) != null) { yield return control; } foreach (T child in FindControlsOfType<T>(ctrl.Controls)) { yield return child; } } } public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance, Func<T, bool> match) where T : class { return FindControlsOfType<T>(instance).Where(match); } The idea here is to find all controls that match a specifc criteria (hence the Func<..) in the controls collection. My question is: Does the second method (that has the Func) first call the first method to find all the controls of type T and then performs the where condition or does the "runtime" optimize the call to perform the where condition on the "whole" enumeration (if you get what I mean). secondly, are there any other optimizations that I can do to the code to perform better. An example can look like this: var checkbox = this.Controls.FindControlsOfType<MyCustomCheckBox>( ctrl => ctrl.CustomProperty == "Test" ) .FirstOrDefault();

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• C++0x rvalue references and temporaries

  - by Doug

  (I asked a variation of this question on comp.std.c++ but didn't get an answer.) Why does the call to f(arg) in this code call the const ref overload of f? void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } My intuition says that the f(string &&) overload should be chosen, because arg needs to be converted to a temporary no matter what, and the temporary matches the rvalue reference better than the lvalue reference. This is not what happens in GCC and MSVC. In at least G++ and MSVC, any lvalue does not bind to an rvalue reference argument, even if there is an intermediate temporary created. Indeed, if the const ref overload isn't present, the compilers diagnose an error. However, writing f(arg + 0) or f(std::string(arg)) does choose the rvalue reference overload as you would expect. From my reading of the C++0x standard, it seems like the implicit conversion of a const char * to a string should be considered when considering if f(string &&) is viable, just as when passing a const lvalue ref arguments. Section 13.3 (overload resolution) doesn't differentiate between rvalue refs and const references in too many places. Also, it seems that the rule that prevents lvalues from binding to rvalue references (13.3.3.1.4/3) shouldn't apply if there's an intermediate temporary - after all, it's perfectly safe to move from the temporary. Is this: Me misreading/misunderstand the standard, where the implemented behavior is the intended behavior, and there's some good reason why my example should behave the way it does? A mistake that the compiler vendors have somehow all made? Or a mistake based on common implementation strategies? Or a mistake in e.g. GCC (where this lvalue/rvalue reference binding rule was first implemented), that was copied by other vendors? A defect in the standard, or an unintended consequence, or something that should be clarified?

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• Should java try blocks be scoped as tightly as possible?

  - by isme

  I've been told that there is some overhead in using the Java try-catch mechanism. So, while it is necessary to put methods that throw checked exception within a try block to handle the possible exception, it is good practice performance-wise to limit the size of the try block to contain only those operations that could throw exceptions. I'm not so sure that this is a sensible conclusion. Consider the two implementations below of a function that processes a specified text file. Even if it is true that the first one incurs some unnecessary overhead, I find it much easier to follow. It is less clear where exactly the exceptions come from just from looking at statements, but the comments clearly show which statements are responsible. The second one is much longer and complicated than the first. In particular, the nice line-reading idiom of the first has to be mangled to fit the readLine call into a try block. What is the best practice for handling exceptions in a funcion where multiple exceptions could be thrown in its definition? This one contains all the processing code within the try block: void processFile(File f) { try { // construction of FileReader can throw FileNotFoundException BufferedReader in = new BufferedReader(new FileReader(f)); // call of readLine can throw IOException String line; while ((line = in.readLine()) != null) { process(line); } } catch (FileNotFoundException ex) { handle(ex); } catch (IOException ex) { handle(ex); } } This one contains only the methods that throw exceptions within try blocks: void processFile(File f) { FileReader reader; try { reader = new FileReader(f); } catch (FileNotFoundException ex) { handle(ex); return; } BufferedReader in = new BufferedReader(reader); String line; while (true) { try { line = in.readLine(); } catch (IOException ex) { handle(ex); break; } if (line == null) { break; } process(line); } }

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• SIP UAS asks for OPTIONS

  - by TacB0sS

  Hey, I have UAC that registers to a UAS, after registration the UAS sends me an OPTIONS request, what should I answer it? only the audio media streams? Update I: Allow me to explain myself better... if I want to invite someone to a session I USE the INVITE method and negotiate the media then, for that specific session. But once I register to the server, and it asks me for OPTIONS, then what should I supply, everything my client supports? once I answer it would it deduce that every INVITE I would request from now on would use these medias? or would I need to supply new media with every request? Update II: Hi Wiz, I was in the process of building a negotiation system, so i tried it out and replied the UAS here is the sort dialog we had: OPTIONS sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP xx.xx.xx.xx:5060;branch=z9hG4bK45b197cb;rport=5060;received=xx.xx.xx.xx From: "Unknown" <sip:[email protected]>;tag=as66cf26df To: <sip:[email protected]> Contact: <sip:[email protected]> Call-ID: [email protected] CSeq: 102 OPTIONS User-Agent: Freeswitch 1.2.3 Max-Forwards: 70 Date: Sat, 05 Jun 2010 12:06:43 GMT Allow: INVITE,ACK,CANCEL,OPTIONS,BYE,REFER,SUBSCRIBE,NOTIFY,INFO Supported: replaces Content-Length: 0 OPTIONS In Response To 102: SIP/2.0 200 OK Via: SIP/2.0/UDP xx.xx.xx.xx:5060;branch=z9hG4bK45b197cb;rport=5060;received=xx.xx.xx.xx From: "Unknown" <sip:[email protected]>;tag=as66cf26df To: <sip:[email protected]> CSeq: 102 OPTIONS Call-ID: [email protected] Allow: INVITE,CANCEL,ACK,BYE,OPTIONS Content-Type: application/sdp Content-Length: 248 v=0 o=310 4515233118481497946 4515233118481497946 IN IP4 10.0.0.1 s=- i=Nu-Art Software - TacB0sS VoIP information c=IN IP4 10.0.0.1 m=audio 40000 RTP/AVP 0 8 101 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:101 telephone-event/8000 This response caused the server to stop sending me the options request, does this means I can only use these parameters with the server now? or as you said, it does not matter? Thanks, Adam.

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