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• What does the C# compiler mean when it prints "an explicit conversion exists"?

  - by Wim Coenen

  If I make an empty test class: public class Foo { } And I try to compile code with this statement: Foo foo = "test"; Then I get this error as expected: Cannot implicitly convert type 'string' to 'ConsoleApplication1.Foo' However, if I change the declaration of Foo from class to interface, the error changes to this (emphasis mine): Cannot implicitly convert type 'string' to 'ConsoleApplication1.Foo'. An explicit conversion exists (are you missing a cast?) What is this "explicit conversion" which is supposed to exist?

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• getnameinfo specifies socklen_t

  - by bobby

  The 2nd arg for the getnameinfo prototype asks for a socklen_t type but sizeof uses size_t. So how can I get socklen_t ? Prototype: int getnameinfo(const struct sockaddr *restrict sa, socklen_t salen, char *restrict node, socklen_t nodelen, char *restrict service, socklen_t servicelen, int flags); Example: struct sockaddr_in SIN; memset(&SIN, 0, sizeof(SIN)); // This should also be socklen_t ? SIN.sin_family = AF_INET; SIN.sin_addr.s_addr = inet_addr(IP); SIN.sin_port = 0; getnameinfo((struct sockaddr *)&SIN, sizeof(SIN) /* socklen_t */, BUFFER, NI_MAXHOST, NULL, 0, 0);

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• Counting entries in a list of dictionaries: for loop vs. list comprehension with map(itemgetter)

  - by Dennis Williamson

  In a Python program I'm writing I've compared using a for loop and increment variables versus list comprehension with map(itemgetter) and len() when counting entries in dictionaries which are in a list. It takes the same time using a each method. Am I doing something wrong or is there a better approach? Here is a greatly simplified and shortened data structure: list = [ {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'biscuits and gravy'}, {'key1': False, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'peaches and cream'}, {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': False, 'filenotfound': 'Abbott and Costello'}, {'key1': False, 'dontcare': False, 'ignoreme': True, 'key2': False, 'filenotfound': 'over and under'}, {'key1': True, 'dontcare': True, 'ignoreme': False, 'key2': True, 'filenotfound': 'Scotch and... well... neat, thanks'} ] Here is the for loop version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True key1 = key2 = 0 for dictionary in list: if dictionary["key1"]: key1 += 1 if dictionary["key2"]: key2 += 1 print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above: Counts: key1: 3, subset key2: 2 Here is the other, perhaps more Pythonic, version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True from operator import itemgetter KEY1 = 0 KEY2 = 1 getentries = itemgetter("key1", "key2") entries = map(getentries, list) key1 = len([x for x in entries if x[KEY1]]) key2 = len([x for x in entries if x[KEY1] and x[KEY2]]) print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above (same as before): Counts: key1: 3, subset key2: 2 I'm a tiny bit surprised these take the same amount of time. I wonder if there's something faster. I'm sure I'm overlooking something simple. One alternative I've considered is loading the data into a database and doing SQL queries, but the data doesn't need to persist and I'd have to profile the overhead of the data transfer, etc., and a database may not always be available. I have no control over the original form of the data. The code above is not going for style points.

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• What is the fastest way to copy content of DVD to hard disc using Linux

  - by Ritesh

  I have gone through some of the links Which talks about fastest way of copying files in windows using FILE_FLAG_NO_BUFFERING and FILE_FLAG_OVERLAPPED . It also talks about how request made for read and write opeartions with BUFFER SIZE as 256KB and 128KB are faster than 1Mb .The link for that is :- Explanation for tiny reads (overlapped, buffered) outperforming large contiguous reads? I am also loking for a Similar method in linux Which allows me to copy the content of my DVD to Hard Disc in a fast Way . So I wanted to know Is there some file operation flags in Linux which would provide me the best result or Which way of Copy in Linux is the best ? My codes are all in c++.

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• How do I implement Advanced combobox in CakePHP

  - by skr

  I have implemented combobox in cakephp using following statement - echo $form->select('brand_id',array($brands),null,array(),'Choose Brand'); for brand and input form for category - echo $form->input('category_id',array('type'=>'select',$categories,'empty'=>'Choose Category')); but none of above option allows me to add my text input to brand or category, like say I want to add an input which is not there in the combobox, how should i go about it. Like a link in the combobox or textbox in combobox? -skr

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• POSTmethod and PHP- login verification

  - by Neethusha

  I wrote a code for login verification..I got output with GET. But i need output with POST since it is more secure.pls let me know if there is any error in my code. javascript code: var xml; function verifyusernamepasswd(pass) { //pass is password that will be passed as parameter xml=new XMLHttpRequest(); var url="http://localhost/loginvalidate.php"; var para="q="+username+"&p="+pass;//username is global xml.setRequestHeader("Content-type", "application/x-www-form-urlencoded"); xml.setRequestHeader("Content-length", para.length); xml.setRequestHeader("Connection", "close"); xml.open("POST",url,true); xml.onreadystatechange=statechanged1; xml.send(para); } function statechanged1() { if(xml.readyState==4) alert(xml.responseText); } php code: <?php $username=$_POST["q"]; $password=$_POST["p"]; $con=mysql_connect("localhost","root","blaze"); if(!$con) { die('Could not connect: '.mysql.error()); } mysql_select_db("BLAZE",$con) or die("No such Db"); $result=mysql_query("SELECT Passwword FROM USERTABLE WHERE Userhandle='$username'"); if($result==null) echo "false"; else if($result!=null) { $row=mysql_fetch_array($result); if((strcmp($row['Passwword'],$password)==0)) echo "true"; else echo "false"; } ?> the verification does not return anything, cos my alert is not displayed at all...pls tell me whats wrong....

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• How do I implement a TextBox that displays "Type here"?

  - by mafutrct

  Displaying "Type here to ..." until the user enters text into a TextBox is a well-known usability feature nowadays. How would one implement this feature in C#? My idea is to override OnTextChanged, but the logic to handle the changes of Text from and to "Type here" is a bit tricky... Displaying "Type here" on initialization and removing it on first input is easy, but I want to display the message every time the entered text becomes empty.

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• Implementing a scrabble trainer

  - by bstullkid

  Hello, I've recently been playing alot of online scrabble so I decided to make a program that quickly searches through a dictionary of 200,000+ words with an input of up to any 26 letters. My first attempt was fail as it took a while when you input 8 or more letters (just a basic look through dictionary and cancel out a letter if its found kind of thing), so I made a tree like structure containing only an array of 26 of the same structure and a flag to indicate the end of a word, doing that It can output all possible words in under a second even with an input of 26 characters. But it seems that when I input 12 or more letters with some of the same characters repeated i get duplicates; can anyone see why I would be getting duplicates with this code? (ill post my program at the bottom) Also, the next step once the duplicates are weeded out is to actually be able to input the letters on the game board and then have it calculate the best word you can make on a given board. I am having trouble trying to figure out a good algorithm that can analyze a scrabble board and an input of letters and output a result; the possible words that could be made I have no problem with but actually checking a board efficiently (ie can this word fit here, or here etc... without creating a non dictionary word in the process on some other string of letters) Anyone have a idea for an approach at that? (given a scrabble board, and an input of 7 letters, find all possible valid words or word sets that you can make) lol crap i forgot to email myself the code from my other computer thats in another state... ill post it on monday when I get back there! btw the dictionary im using is sowpods (http://www.calvin.edu/~rpruim/scrabble/ospd3.txt)

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• mysql display each day in a month

  - by Jason

  during a month, display the infor each date, order by date, but this infor is empty in some day. how can i still display each day as a row? Product date ----------------- 20 2008-01-01 10 2008-01-02 20 2008-01-03 10 2008-01-05 09 2008-01-08 30 2008-01-09 result: Product date ----------------- 20 2008-01-01 10 2008-01-02 20 2008-01-03 0 2008-01-04 10 2008-01-05 0 2008-01-06 0 2008-01-07 09 2008-01-08 30 2008-01-09

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• How to name variables wich are structs

  - by evilpie

  Hello, i often work on private projects using the WinApi, and as you might know, it has thousands of named and typedefed structs like MEMORY_BASIC_INFORMATION. I will stick to this one in my question, what still is preferred, or better when you want to name a variable of this type. Is there some kind of style guide for this case? For example if i need that variable for the VirtualQueryEx function. Some ideas: MEMORY_BASIC_INFORMATION memoryBasicInformation; MEMORY_BASIC_INFORMATION memory_basic_information; Just use the name of the struct non captialized and with or without the underlines. MEMORY_BASIC_INFORMATION basicInformation; MEMORY_BASIC_INFORMATION information; Short form? MEMORY_BASIC_INFORMATION mbi; I often see this style, using the abbreviation of the struct name. MEMORY_BASIC_INFORMATION buffer; VirtualQueryEx defines the third parameter lpBuffer (where you pass the pointer to the struct), so using this name might be an idea, too. Cheers

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• How to play multiple online videos on IOS continuously

  - by Matt.Z

  The scenario is like this: I have some long video, and slice it into small files(mp4, for example: 5 min per file), put them under some website. I wanna play (on IOS) these mp4 videos continuously, one by one, try to do not let user feel there has a pause between video pieces. So I need to buffer next video when I play current one. But I don't know where to start. What should I do? Can anyone give me some information of related documentation or source code I can study with?

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• Spider a Website and Return URLs Only

  - by Rob Wilkerson

  I'm not quite sure how best to define/articulate this, but I'm looking for a way to pseudo-spider a website. The key is that I don't actually want the content, but rather a simple list of URIs. I can get reasonably close to this idea with Wget using the --spider option, but when piping that output through a grep, I can't seem to find the right magic to make it work: wget --spider --force-html -r -l1 http://somesite.com | grep 'Saving to:' The grep filter seems to have absolutely no affect on the wget output. Have I got something wrong or is there another tool I should try that's more geared towards providing this kind of limited result set? Thanks. UPDATE So I just found out offline that, by default, wget writes to stderr. I missed that in the man pages (in fact, I still haven't found it if it's in there). Once I piped the return to stdout, I got closer to what I need: wget --spider --force-html -r -l1 http://somesite.com 2>&1 | grep 'Saving to:' I'd still be interested in other/better means for doing this kind of thing, if any exist.

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• clear html webpage?

  - by noname

  i am currently developing a crawler that crawls all links on the web and displays them in the web browser (and saving it of course). but after some hours there will be a huge list displayed on the web browser and i want to only display lets say 1000 links at the same time. then i clear the html and display another 1000 links. this is also good for the RAM or it will eat up all memory. how do i clear the web browser screen? EDIT: i have seen some scripts using some flush buffer functions. has this anything to do with my case?

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• add color style to value based on condition

  - by rod

  Hi All, How do I conditionally add the style 'color:red' to the .CurrentDifference if the value happens to be a negative value? Thanks, rod. <div class="sRow"> <div class="sLabel p40"> Difference: </div> <%= (!String.IsNullOrEmpty(Model.Amount)?Model.Amount.CurrentDifference.ToString("c"):string.Empty) %> </div>

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• How to properly translate the "var" result of a lambda expression to a concrete type?

  - by CrimsonX

  So I'm trying to learn more about lambda expressions. I read this question on stackoverflow, concurred with the chosen answer, and have attempted to implement the algorithm using a console app in C# using a simple LINQ expression. My question is: how do I translate the "var result" of the lambda expression into a usable object that I can then print the result? I would also appreciate an in-depth explanation of what is happening when I declare the outer => outer.Value.Frequency (I've read numerous explanations of lambda expressions but additional clarification would help) C# //Input : {5, 13, 6, 5, 13, 7, 8, 6, 5} //Output : {5, 5, 5, 13, 13, 6, 6, 7, 8} //The question is to arrange the numbers in the array in decreasing order of their frequency, preserving the order of their occurrence. //If there is a tie, like in this example between 13 and 6, then the number occurring first in the input array would come first in the output array. List<int> input = new List<int>(); input.Add(5); input.Add(13); input.Add(6); input.Add(5); input.Add(13); input.Add(7); input.Add(8); input.Add(6); input.Add(5); Dictionary<int, FrequencyAndValue> dictionary = new Dictionary<int, FrequencyAndValue>(); foreach (int number in input) { if (!dictionary.ContainsKey(number)) { dictionary.Add(number, new FrequencyAndValue(1, number) ); } else { dictionary[number].Frequency++; } } var result = dictionary.OrderByDescending(outer => outer.Value.Frequency); // How to translate the result into something I can print??

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• swfupload session problem destroy session

  - by saquib

  Hello Friends, I have a problem with swfupload. I am passing session_id() like this /upload-file.php?s=189477fcfa1ec7f630e70a09e1e84cae but its not maintaining session and destroying my current session (logging me out) here is code in file upload. <?php if(isset($_GET['s'])) { session_id($_GET['s']); session_start(); require_once 'admin/class/user.php'; $u = new User(); //Check for user logged in if($u->islogged() == FALSE) { header("location: index.php"); exit(); code continue ..... } because am not logged in server redirect me to the index.php this is swfupload debugger window output SWF DEBUG: ----- END SWF DEBUG OUTPUT ---- SWF DEBUG: SWF DEBUG: Event: fileDialogStart : Browsing files. Multi Select. Allowed file types: *.jpg SWF DEBUG: Select Handler: Received the files selected from the dialog. Processing the file list... SWF DEBUG: Event: fileQueued : File ID: SWFUpload_0_0 SWF DEBUG: Event: fileDialogComplete : Finished processing selected files. Files selected: 1. Files Queued: 1 SWF DEBUG: StartUpload: First file in queue SWF DEBUG: Event: uploadStart : File ID: SWFUpload_0_0 SWF DEBUG: ReturnUploadStart(): File accepted by startUpload event and readied for upload. Starting upload to /upload-file.php?s='189477fcfa1ec7f630e70a09e1e84cae' for File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress (OPEN): File ID: SWFUpload_0_0 SWF DEBUG: Event: uploadProgress: File ID: SWFUpload_0_0. Bytes: 317793. Total: 317793 SWF DEBUG: Event: uploadError: HTTP ERROR : File ID: SWFUpload_0_0. HTTP Status: 302. SWF DEBUG: Event: uploadComplete : Upload cycle complete. SWF DEBUG: StartUpload: First file in queue SWF DEBUG: StartUpload(): No files found in the queue.

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• Can a page opt out of IIS 7 compression?

  - by Glen Little

  My pages are automatically being compressed by IIS7 with GZIP. That is great... but, for one particular page, I need to stream it to the user, using Response.Flush() when needed. But when the output is being compressed, the IIS server seems to collect all my output until the page is done before compressing and sending it to the client. That nullifies my attempt to Flush the content out to the user. Is there a way that I can have this one page opt out of the compression? One possible option I've determined that if I manually set the content type to one that does not match the IIS configuration at c:\windows\system32\inetsrv\config\applicationhost.config, then IIS will not compress it. Eg. Response.ContentType = "x-text/html". This works okay with IE8, as it falls back to display the HTML. But Firefox will ask the user what to do with the unknown file type. This could work, if there was another Mime Type I could use that browsers would accept as HTML, that is not matched in the applicationhost.config. For reference, these are the mime types that will be compressed: <add mimeType="text/*" enabled="true" /> <add mimeType="message/*" enabled="true" /> <add mimeType="application/x-javascript" enabled="true" /> <add mimeType="application/atom+xml" enabled="true" /> <add mimeType="application/xaml+xml" enabled="true" /> Others options? Are there other options to opt out of compression?

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• adding other parameter to function

  - by Ronnie Chester Lynwood

  hello. i got a function that listing downloads in a table with foreach. it's also lists searched term, search type. public function fetchDownloads($displaySite=true) { $downloads = array(); $sqlWhere = ""; if(isset($this->q)) { if(strlen($this->q) <= $this->recents_length && !empty($this->q)) { $insertRecent = $this->processDataHook("insertRecent",$this->q); if($insertRecent) { if(!@mysql_query("INSERT INTO wcddl_recents (query) VALUES ('".$this->qSQL."')")) { @mysql_query("UPDATE wcddl_recents SET searches = searches+1 WHERE query = '".$this->qSQL."'"); } } } if($this->search_type == "narrow") { $sqlWhere = " WHERE title LIKE '%".mysql_real_escape_string(str_replace(" ","%",$this->q))."%'"; } elseif($this->search_type == "wide") { $qExp = explode(" ",$this->q); $sqlWhere = array(); foreach($qExp as $fq) $sqlWhere[] = "title LIKE '%".mysql_real_escape_string($fq)."%'"; $sqlWhere = implode(" OR ",$sqlWhere); $sqlWhere = " WHERE (".$sqlWhere.")"; } } if(isset($this->type)) { if(!empty($sqlWhere)) { $sqlWhere .= " AND type = '".$this->typeSQL."'"; } else { $sqlWhere = " WHERE type = '".$this->typeSQL."'"; } } $sqlWhere = $this->processDataHook("fetchDownloadsSQLWhere",$sqlWhere); $this->maxPages = mysql_query("SELECT COUNT(*) FROM wcddl_downloads".$sqlWhere.""); $this->maxPages = mysql_result($this->maxPages,0); $this->numRows = $this->maxPages; $this->maxPages = ceil($this->maxPages/$this->limit); $sqlMain = "SELECT id,sid,title,type,url,dat,views,rating FROM wcddl_downloads".$sqlWhere." ORDER BY ".(isset($this->sqlOrder) ? mysql_real_escape_string($this->sqlOrder) : "id DESC")." LIMIT ".$this->pg.",".$this->limit.""; $sqlMain = $this->processDataHook("whileFetchDownloadsSQL",$sqlMain); $sqlMain = mysql_query($sqlMain); $this->processHook("whileFetchDownloads"); while($row = mysql_fetch_assoc($sqlMain)) { if($displaySite) { $downloadSite = mysql_query("SELECT name as sname, url as surl, rating as srating FROM wcddl_sites WHERE id = '".$row['sid']."'"); $downloadSite = mysql_fetch_assoc($downloadSite); $row = array_merge($row,$downloadSite); } $downloads_current = $this->mapit($row,array("stripslashes","strip_tags")); $downloads_current = $this->processDataHook("fetchDownloadsRow",$downloads_current); $downloads[] = $downloads_current; } $this->pageList = $this->getPages($this->page,$this->maxPages); $this->processHook("endFetchDownloads"); return $downloads; } I want to add if $_REQUEST['site'] is set, order downloads by sname that catching from wcddl_sites.

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• What does the windbg command "kd" do?

  - by Oskar

  I ran kd by mistake and got some output that inteerested me, a reference to a line of code in my module that I can't see on the call stack of any thread. The lines weren't the beginnning of the method so I don't think the reference is to a function pointer, but possibly the result of an exception being stored in memory??? Of course, that happens to be what I'm looking for... Update: The stack trace of the exception is: 0:000> kb *** Stack trace for last set context - .thread/.cxr resets it ChildEBP RetAddr Args to Child 0174f168 734ea84f 2cb9e950 00000000 2cb9e950 kernel32!LoadTimeZoneInformation+0x2b 0174f1c4 734ead92 00000022 00000001 000685d0 msvbvm60! RUN_INSTMGR::ExecuteInitTerm+0x178 0174f1f8 734ea9ee 00000000 0000002f 2dbc2abc msvbvm60! RUN_INSTMGR::CreateObjInstanceWithParts+0x1e4 0174f278 7350414e 2cb9e96c 00000000 0174f2f0 msvbvm60! RUN_INSTMGR::CreateObjInstance+0x14d 0174f2e4 734fa071 00000000 2cb9e96c 0174f2fc msvbvm60!RcmConstructObjectInstance+0x75 0174f31c 00976ef1 2cb9e950 00591bc0 0174fddc msvbvm60!__vbaNew+0x21 and into our code (create a new Form derived class) the dds output: 0:000> dds esp-0x40 esp+0x100 0174f05c 00000000 0174f060 00000000 0174f064 00000000 0174f068 00000000 0174f06c 00000000 0174f070 00000000 0174f074 00000000 0174f078 00000000 0174f07c 00000000 0174f080 00000000 0174f084 00000000 0174f088 00000000 0174f08c 00000000 0174f090 00000000 0174f094 00000000 0174f098 00000000 0174f09c 007f4f9b ourDll!formDerivedClass::Form_Initialize+0x10b [C:\Buildbox\formDerivedClass.frm @ 1452] etc which seems to indicate that Initialize is being called even though it isn't on the stack trace of either this exception or any of the threads. As suggested, it might all be a mismatch between pdbs and dlls, but it seems a coincidence that we end up in the right classes and methods

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• Open a file with su/sudo inside Emacs

  - by Chris Conway

  Suppose I want to open a file in an existing Emacs session using su or sudo, without dropping down to a shell and doing sudoedit or sudo emacs. One way to do this is (require 'tramp) C-c C-f /sudo::/path/to/file but this requires an expensive round-trip through SSH. Is there a more direct way? [EDIT] @JBB is right. I want to be able to invoke su/sudo to save as well as open. It would be OK (but not ideal) to re-authorize when saving. What I'm looking for is variations of find-file and save-buffer that can be "piped" through su/sudo.

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• Change asp message box header / title

  - by Jb Meris

  how can i change the title of my message box here is my code behind: string myStringVariable1 = string.Empty; myStringVariable1 = "Policy Number:" + " " + txtPolNo.Text.ToString() + " " + "with Issuance office:" + " " + dropIssOff.Text.ToString() + " " + "was not found on the database. Please make sure that your inputs are correct."; ClientScript.RegisterStartupScript(this.GetType(), "myalert", "alert('" + myStringVariable1 + "');", true);

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• how to disable vim autocomplete popup for plain text files?

  - by doorfly

  After literally days of tweaking, I think I got vim's autocomplete (omnicomplete + Acp plugin) to work acceptably. But the annoying thing is that it is still enabled for plain text files so I would have to type :DisableAcp for README or plain text files. How do I add logic to my vimrc so that if it detects an empty filetype it disables the Acp on startup? here is what I wrote: if &filetype == "" let g:acp_enableStartup = 0 endif but this disables Acp on start up for all files.

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• How to handle failure to release a resource which is contained in a smart pointer?

  - by cj

  How should an error during resource deallocation be handled, when the object representing the resource is contained in a shared pointer? Smart pointers are a useful tool to manage resources safely. Examples of such resources are memory, disk files, database connections, or network connections. // open a connection to the local HTTP port boost::shared_ptr<Socket> socket = Socket::connect("localhost:80"); In a typical scenario, the class encapsulating the resource should be noncopyable and polymorphic. A good way to support this is to provide a factory method returning a shared pointer, and declare all constructors non-public. The shared pointers can now be copied from and assigned to freely. The object is automatically destroyed when no reference to it remains, and the destructor then releases the resource. /** A TCP/IP connection. */ class Socket { public: static boost::shared_ptr<Socket> connect(const std::string& address); virtual ~Socket(); protected: Socket(const std::string& address); private: // not implemented Socket(const Socket&); Socket& operator=(const Socket&); }; But there is a problem with this approach. The destructor must not throw, so a failure to release the resource will remain undetected. A common way out of this problem is to add a public method to release the resource. class Socket { public: virtual void close(); // may throw // ... }; Unfortunately, this approach introduces another problem: Our objects may now contain resources which have already been released. This complicates the implementation of the resource class. Even worse, it makes it possible for clients of the class to use it incorrectly. The following example may seem far-fetched, but it is a common pitfall in multi-threaded code. socket->close(); // ... size_t nread = socket->read(&buffer[0], buffer.size()); // wrong use! Either we ensure that the resource is not released before the object is destroyed, thereby losing any way to deal with a failed resource deallocation. Or we provide a way to release the resource explicitly during the object's lifetime, thereby making it possible to use the resource class incorrectly. There is a way out of this dilemma. But the solution involves using a modified shared pointer class. These modifications are likely to be controversial. Typical shared pointer implementations, such as boost::shared_ptr, require that no exception be thrown when their object's destructor is called. Generally, no destructor should ever throw, so this is a reasonable requirement. These implementations also allow a custom deleter function to be specified, which is called in lieu of the destructor when no reference to the object remains. The no-throw requirement is extended to this custom deleter function. The rationale for this requirement is clear: The shared pointer's destructor must not throw. If the deleter function does not throw, nor will the shared pointer's destructor. However, the same holds for other member functions of the shared pointer which lead to resource deallocation, e.g. reset(): If resource deallocation fails, no exception can be thrown. The solution proposed here is to allow custom deleter functions to throw. This means that the modified shared pointer's destructor must catch exceptions thrown by the deleter function. On the other hand, member functions other than the destructor, e.g. reset(), shall not catch exceptions of the deleter function (and their implementation becomes somewhat more complicated). Here is the original example, using a throwing deleter function: /** A TCP/IP connection. */ class Socket { public: static SharedPtr<Socket> connect(const std::string& address); protected: Socket(const std::string& address); virtual Socket() { } private: struct Deleter; // not implemented Socket(const Socket&); Socket& operator=(const Socket&); }; struct Socket::Deleter { void operator()(Socket* socket) { // Close the connection. If an error occurs, delete the socket // and throw an exception. delete socket; } }; SharedPtr<Socket> Socket::connect(const std::string& address) { return SharedPtr<Socket>(new Socket(address), Deleter()); } We can now use reset() to free the resource explicitly. If there is still a reference to the resource in another thread or another part of the program, calling reset() will only decrement the reference count. If this is the last reference to the resource, the resource is released. If resource deallocation fails, an exception is thrown. SharedPtr<Socket> socket = Socket::connect("localhost:80"); // ... socket.reset();

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• .NET SerialPort.Read skipps bytes

  - by Lukas Rieger

  Solution Reading the data byte wise via "port.ReadByte" is too slow, the problem is inside the SerialPort class. i changed it to reading bigger chunks via "port.Read" and there are now no buffer overruns. although i found the solution myself, writing it down helped me and maybe someone else has the same problem and finds this via google... (how can i mark it as answered?) EDIT 2 by setting port.ReadBufferSize = 2000000; i can delay the problem for ~30 seconds. so it seems, .Net really is too slow... since my application is not that critical, i just set the buffer to 20MB, but i am still interested in the cause. EDIT i just tested something i had not thought of before (shame on me): port.ErrorReceived += (object self, SerialErrorReceivedEventArgs se_arg) => { Console.Write("| Error: {0} | ", System.Enum.GetName(se_arg.EventType.GetType(), se_arg.EventType)); }; and it seems that i have an overrun. Is the .Net implementation too slow for 500k or is there an error on my side? Original Question i built a very primitive oszilloscope (avr, which sends adc data over uart to an ftdi chip). On the pc side i have a WPF Programm that displays this data. The Protokoll is: two sync bytes (0xaffe) - 14 data bytes - two sync bytes - 14 data bytes - ... i use 16bit values, so inside the 14 data bytes are 7 channels (lsb first). I verified the uC Firmware with hTerm, and it does send and receive everything correct. But, if i try to read the data with C#, sometimes some bytes are lost. The oszilloscop programm is a mess, but i created a small sample application, which has the same symptoms. I added two extension methods to a) read one byte from the COM Port and ignore -1 (EOF) and b) wait for the sync pattern. The sample programm first syncs onto the data stream by waiting for (0xaffe) and then compares the received bytes with the expected values. the loop runs a few times until an assert failed message pops up. I could not find anything about lost bytes via google, any help would be appreciated. Code using System; using System.Collections.Generic; using System.Diagnostics; using System.IO.Ports; using System.Linq; using System.Text; using System.Threading.Tasks; namespace SerialTest { public static class SerialPortExtensions { public static byte ReadByteSerial(this SerialPort port) { int i = 0; do { i = port.ReadByte(); } while (i < 0 || i > 0xff); return (byte)i; } public static void WaitForPattern_Ushort(this SerialPort port, ushort pattern) { byte hi = 0; byte lo = 0; do { lo = hi; hi = port.ReadByteSerial(); } while (!(hi == (pattern >> 8) && lo == (pattern & 0x00ff))); } } class Program { static void Main(string[] args) { //500000 8n1 SerialPort port = new SerialPort("COM3", 500000, Parity.None, 8, StopBits.One); port.Open(); port.DiscardInBuffer(); port.DiscardOutBuffer(); //Sync port.WaitForPattern_Ushort(0xaffe); byte hi = 0; byte lo = 0; int val; int n = 0; // Start Loop, the stream is already synced while (true) { //Read 7 16-bit values (=14 Bytes) for (int i = 0; i < 7; i++) { lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val != 0xaffe); } //Read two sync bytes lo = port.ReadByteSerial(); hi = port.ReadByteSerial(); val = ((hi << 8) | lo); Debug.Assert(val == 0xaffe); n++; } } } }

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• Ruby : UTF-8 IO

  - by subtenante

  I use ruby 1.8.7. I try to parse some text files containing greek sentences, encoded in UTF-8. (I can't much paste here sample files, because they are subject to copyright. Really just some greek text encoded in UTF-8.) I want, for each file, to parse the file, extract all the words, and make a list of each new word found in this file. All that saved to one big index file. Here is my code : #!/usr/bin/ruby -KU def prepare_line(l) l.gsub(/^\s*[ST]\d+\s*:\s*|\s+$|\(\d+\)\s*/u, "") end def tokenize(l) l.split /['·.;!:\s]+/u end $dict = {} $cpt = 0 $out = File.new 'out.txt', 'w' def lesson(file) $cpt = $cpt + 1 file.readlines.each do |l| $out.puts l l = prepare_line l tokenize(l).each do |t| unless $dict[t] $dict[t] = $cpt $out.puts " #{t}\n" end end end end Dir.new('etc/').each do |filename| f = File.new("etc/#{filename}") unless File.directory? f lesson f end end Here is part of my output : ?@???†?†?????????? ?...[snip very long hangul/hanzi mishmash]... ????????†? ???N2 : ?e?te?? (2) µ???µa (Note that the puts l part seems to work fine, at the end of the given output line.) Any idea what is wrong with my code ? (General comments about ruby idioms I could use are very welcome, I'm really a beginner.)

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