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• Why are Python exceptions named "Error"?

  - by Elena

  Why are Python exceptions named "Error" (e.g. ZeroDivisionError, NameError, TypeError etc) and not "Exception" (e.g. ZeroDivisionException, NameException, TypeException etc). I come from a Java background and started to learn Python recently, as such this is confusing because in java there is a distinction between error and exception. Is there a difference in Python also or not? Can someone explain or point me to some documentation explaining it? Thank you!

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• Java: dangerous self-returning-recursive function by IOException?

  - by HH

  I had very errorsome Exception handling with if-clauses. An exception occurs if not found path. An exception returns the function again. The function is recursive. Safe? $ javac SubDirs.java $ java SubDirs Give me an path. . HELLO com TOASHEOU google common annotations base collect internal Give me an path. IT WON'T FIND ME, SO IT RETURNS ITSELF due to Exception caught Give me an path. $ cat SubDirs.java import java.io.*; import java.util.*; public class SubDirs { private List<File> getSubdirs(File file) throws IOException { List<File> subdirs = Arrays.asList(file.listFiles(new FileFilter() { public boolean accept(File f) { return f.isDirectory(); } })); subdirs = new ArrayList<File>(subdirs); List<File> deepSubdirs = new ArrayList<File>(); for(File subdir : subdirs) { deepSubdirs.addAll(getSubdirs(subdir)); } subdirs.addAll(deepSubdirs); return subdirs; } public static void search() { try{ BufferedReader in = new BufferedReader(new InputStreamReader(System.in)); String s; System.out.println("Give me an path."); while ((s = in.readLine()) != null && s.length() != 0){ SubDirs dirs = new SubDirs(); List<File> subDirs = dirs.getSubdirs(new File(s)); for ( File f : subDirs ) { System.out.println(f.getName()); } System.out.println("Give me an path."); } }catch(Exception e){ // Simple but is it safe? search(); } } public static void main(String[] args) throws IOException { search(); } }

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• How to do REST securely and with sensitive data?

  - by Earlz

  Hello, we are implementing a new web service. The web service will be a store of sensitive data and there are multiple users types with different permissions. So some user types can't access(and some can't change, and so on) certain types of data. How would this work in REST? I'm very new to REST, so sorry if this sounds noobish.

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• Easiest Java image processing solution

  - by Daniel Fath

  Here is the deal, in my Java project I have to make a composite document that combines both text and images; So I'm looking for a way to manipulate pictures (rotate, change size, that sort of thing). The API I'm looking for should be clear and easy to learn (preferably with some examples), it should cover the basic transformations I made above - rotate,change size, eventually crop.

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• Unable to connect on socket across different networks.

  - by maleki

  I am having trouble connecting my online application to others across another network. I am able to give them the hostAddress to connect when we are on the same network but when we are doing it across the internet the generated host address doesn't allow a connection, nor does using the ip address gotten from online sites such as whatismyip.com My biggest issue isn't debugging this code, because it works over intra-network but The server doesn't see attempts when we try to move to different networks. Also, the test ip I am using is 2222. InetAddress addr = InetAddress.getLocalHost(); String hostname = addr.getHostName(); System.out.println("Hostname: " + hostname); System.out.println("IP: " + addr.getHostAddress()); I display the host to the server when it is starting if (isClient) { System.out.println("Client Starting.."); clientSocket = new Socket(host, port_number); } else { System.out.println("Server Starting.."); echoServer = new ServerSocket(port_number); clientSocket = echoServer.accept(); System.out.println("Warning, Incoming Game.."); }

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• bitset to dynamic bitset

  - by mr.bio

  Hi.. I have a function where i use bitset.Now i need to convert it to a dynamic bitset.. but i don't know how. Can somebody help me ? set<string> generateCandidates(set<string> ck,unsigned int k){ set<string> nk ; for (set<string>::const_iterator p = ck.begin( );p != ck.end( ); ++p){ for (set<string>::const_iterator q = ck.begin( );q != ck.end( ); ++q){ bitset<4> bs1(*p); bitset<4> bs2(*q); bs1|= bs2 ; if(bs1.count() == k){ nk.insert(bs1.to_string<char,char_traits<char>,allocator<char> >()); } } } return nk; }

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• Unreachable statement when using return in finally?

  - by abson

  this compiles class ex1 { public int show() { try { int a=10/10; return 10; } catch(ArithmeticException e) { System.out.println(e); } finally { System.out.println("Finally"); } System.out.println("hello"); return 20; } } on the other hand this doesn't class ex15 { public int show() { try { int a=10/0; return 10; } catch(ArithmeticException e) { System.out.println(e); } finally { System.out.println("Finally"); return 40; } System.out.println("hello"); return 20; } } and gives unreachable statement System.out.println("hello"); error. why is it so?

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• Why can't I find `len(list)` in Python?

  - by FarmBoy

  I'm new to Python. I have a method that begins: def foo(self, list): length = len(list) I've called len() successfully in other cases, but here I get: TypeError: object of type 'type' has no len() How do I convince Python that this object passed in is a list? What am I missing?

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• How do I begin reading source code?

  - by anonnoir

  I understand the value of reading source code, and I am trying my best to read as much as I can. However, every time I try getting into a 'large' (i.e. complete) project of sorts, I am overwhelmed. For example, I use Anki a lot when revising languages. Also, I'm interested in getting to know how an audio player works (because I have some project ideas), hence quodlibet on Google Code. But whenever I open the source code folders for the above programs, there are just so many files that I don't know where or what to begin with. I think that I should start with files marked init.py but I can't see the logical structure of the programs, or what reasoning was applied when the original writer divided his modules the way he did. Hence, my questions: How/where should I begin reading source? Any general tips or ideas? How does a programmer keep in mind the overall structure and logic of the program, especially for large projects, and is it common not to document that structure? As an open source reader, must I look through all of the code and get a bird's eye view of the code and libraries, before even being able to proceed? Would an IDE like Eclipse SDK (with PyDev) help with code-reading? Thanks for the help; I really appreciate your helping me.

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• Type-conditional controls in Haskell

  - by estanford

  I'm going through the 99 Haskell problems to build my proficiency with the language. On problem 7 ("Flatten a nested list structure"), I found myself wanting to define a conditional behavior based on the type of argument passed to a function. That is, since *Main> :t 1 1 :: (Num t) => t *Main> :t [1,2] [1,2] :: (Num t) => [t] *Main> :t [[1],[2]] [[1],[2]] :: (Num t) => [[t]] (i.e. lists nested at different levels have different data types) it seems like I should be able to write a function that can read the type of the argument, and then behave accordingly. My first attempt was along these lines: listflatten l = do if (:t l) /= ((Num t) => [t]) then listflatten (foldl (++) [] l) else id l But when I try to do that, Haskell returns a parse error. Is Haskell flexible enough to allow this sort of type manipulation, do I need to find another way?

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• How do I exit from a function?

  - by every_answer_gets_a_point

  i know that in vb.net you can just do Exit Sub but i would like to know how do i exit a click event in a button? here's my code: private void button1_Click(object sender, EventArgs e) { if (textBox1.Text == "" || textBox2.Text == "" || textBox3.Text == "") { //exit this event } }

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• jQuery: Checking for length of ul and removing an li element?

  - by Legend

  I am trying to remove the last <li> element from a <ul> element only if it exceeds a particular length. For this, I am doing something like this: var selector = "#ulelement" if($(selector).children().length > threshold) { $(selector + " >:last").remove(); } I don't like the fact that I have to use the selector twice. Is there a shorter way to do this? Something like a "remove-if-length-greater-than-threshold" idea. I was thinking that maybe there is a way to do this using the live() function but I have no idea how.

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• Changing classes on multiple divs when selecting specific radio buttons

  - by Rob

  Hey everyone I got a javascript problem I can't seem to find a specific solution for on the web. What I want to be able to do is select one of the radio buttons and have that change the class of #home-right to either .rackmount or .shipping and add the class of .displaynone to the type of dimensions I don't want shown. <div id="home-right" class="rackmount"> <h4 class="helvneuebcn">Case Finder</h4> <div class="cta-options"> <input type="radio" value="Shipping and Storage" name="" checked> Shipping and Storage<br/> <input type="radio" value="Rackmount Enclosures" name=""> Rackmount Enclosures<br/> </div> <div class="shipping-dimensions displaynone"> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">H x </span></div> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">W x </span></div> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">L</span></div> </div> <div class="rackmount-dimensions"> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">U Height x </span></div> <div class="dimensions"><input type="text" class="size"><span class="helvneuemd">Rack Depth</span></div> </div> <div class="clear"></div> <input type="button" value="Submit" class="findcase"> </div>

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• exceptions with python unicode encode/decode functions (why doesn't errors=ignore actually ignore th

  - by gatoatigrado

  Does anyone know why the string conversion functions throw exceptions when errors="ignore" is passed? How can I convert from regular Python string objects to unicode without errors being thrown? Thanks very much! python -c "import codecs; codecs.open('tmp', 'wb', encoding='utf8', errors='ignore').write('?????')" returns Traceback (most recent call last): File "", line 1, in File "/usr/lib/python2.6/codecs.py", line 686, in write return self.writer.write(data) File "/usr/lib/python2.6/codecs.py", line 351, in write data, consumed = self.encode(object, self.errors) UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 0: ordinal not in range(128)

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• I'm having trouble with using std::stack to retrieve the values from a recursive function.

  - by Peter Stewart

  Thanks to the help I received in this post: http://stackoverflow.com/questions/2761918/how-do-i-use-this-in-a-member-function I have a nice, concise recursive function to traverse a tree in postfix order: void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } cout<<cargo<<"\n"; return; }; Now I need to evaluate the values and operators as they are returned. My problem is how to retrieve them. I tried the std::stack: #include <stack> stack <char*> s; void Node::postfix() { if (left != __nullptr) { left->postfix(); } if (right != __nullptr) { right->postfix(); } s.push(cargo); return; }; but when I tried to access it in main() while (!s.empty()) { cout<<s.top<<"\n"; s.pop; } I got the error: 'std::stack<_Ty::top': function call missing argument list; use '&std::stack<_Ty::top' to create a pointer to member' I'm stuck. Another question to follow shortly.

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• I'm capturing keys on my WinForm but I'm trying to see if the pressed key is a 'String' - getting an

  - by Sergio Tapia

  Here's my code: void gkh_KeyDown(object sender, KeyEventArgs e) { if (e.KeyCode == neededLetter as Keys) { if (neededLetter == "n") { neededLetter = "o"; } else if (neededLetter == "o") { neededLetter = "t"; } else if (neededLetter == "t") { neededLetter = "e"; } else if (neededLetter == "e") { this.Show(); } } else { neededLetter = "n"; } } I'm getting an error on the first If block: The as operator must be used with a reference type or nullable type

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• ActionScript 3.0: placing code on stage/MC timelines a la AS2 instead of in classes

  - by BoltClock

  I'm aware that ActionScript 3.0 is designed from the ground up to be a largely object-oriented language and using it means less or even no timeline code in Flash documents. I'm quite experienced with OOP and am comfortable writing classes. However, since I mostly use Flash for animations, I hardly ever need to write ActionScript code other than for preloaders, subtitles, quality controls, website links and so on. In fact, I still set my Flash movies to use AS2 to this day because I'm used to gotoAndPlay()/gotoAndStop(), AS2 preloaders, subtitles, quality controls and even getURL(). Of course, I really want to move on now that practically everyone's on Flash Player 9 or 10 and now that I've dabbled with other OO languages like Java, C# and Objective-C too. I'm a complete newcomer to AS3 and am not very learned with AS2 either. Considering my current use of ActionScript, are there any cases where it's still OK to use very simple AS3 code in the timeline instead of moving code to a class, especially since moving to a class might mean unnecessarily increasing the number of LOC from 4 to 40? (Heck, is the latter case ('instead of ...') even a valid concern at all?)

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• Microsoft C Compiler: Inline variable declaration?

  - by Rosarch

  I'm writing C in Visual Studio 2010. The compiler doesn't seem to want to let me use inline variable declarations. The following code produces an error: unsigned int fibonacci_iterative(unsigned int n) { if (n == 0) { return 0; } if (n == 1) { return 1; } unsigned int prev_prev = 0; // error unsigned int prev = 1; // error unsigned int next = 0; // error for (int term_number = 0; term_number < n; term_number++) { unsigned int temp = prev_prev + prev; prev = next; prev_prev = prev; next = temp; } return next; } Error: error C2143: syntax error : missing ';' before 'type' error C2143: syntax error : missing ';' before 'type' error C2143: syntax error : missing ';' before 'type' Why is this happening? Is there a setting to make the compiler not so strict?

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• Trying to manually recreate a simple generate/scaffolding script

  - by montooner

  I'm trying to understand Rails from the ground up. I want to learn how to manually create basic show-all/show-single/CRUD functionality in the framework. I currently am working on the display-all functionality, but am stopped by an error when I try to request all items in the Products db Here are the steps I've taken so far: script/generate controller Products script/generate model Products rake db:migrate modified products_controller.rb to add: def index() { @products = Product.all} (error: uninitialized constant ProductsController::Product) ideally, dump all orders in the view What's the fix?

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• Haskell simple compilation bug

  - by fmsf

  I'm trying to run this code: let coins = [50, 25, 10, 5, 2,1] let candidate = 11 calculate :: [Int] calculate = [ calculate (x+candidate) | x <- coins, x > candidate] I've read some tutorials, and it worked out ok. I'm trying to solve some small problems to give-me a feel of the language. But I'm stuck at this. test.hs:3:0: parse error (possibly incorrect indentation) Can anyone tell me why? I've started with haskell today so please go easy on the explanations. I've tried to run it like: runghc test.hs ghc test.hs but with: ghci < test.hs it gives this one: <interactive>:1:10: parse error on input `=' Thanks

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• Java: define terms initialization, declaration and assignment

  - by HH

  I find the defs circular statements, the subjects are defined by their verbs but the verbs are undefined! So how do you define them? The question is central to understand the term final, related. The Circular Definitions itialization: to initilise a variable. It can be can be done at the time of declaration. assignment: to assign value to a variable. It can be done anywhere. declaration: to declare value to a variable.

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• Java: design problem with final-value and empty constructor

  - by HH

  $ javac InitInt.java InitInt.java:7: variable right might not have been initialized InitInt(){} ^ 1 error $ cat InitInt.java import java.util.*; import java.io.*; public class InitInt { private final int right; // Design Problem? // I feel the initialization problem is just due to bad style. InitInt(){} InitInt{ // Still the error, "may not be initialized" // How to initialise it? if(snippetBuilder.length()>(charwisePos+25)){ right=charwisePos+25; }else{ right=snippetBuilder.length()-1; } } public static void main(String[] args) { InitInt test = new InitInt(); System.out.println(test.getRight()); } public int getRight(){return right;} } Partial Solutions and Suggestions use "this" to access methods in the class, instead of creating empty constructor change final to non-final with final field value: initialize all final values in every constructor remove the empty constructor, keep your code simple and clean

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• Purpose of private members in a class

  - by wrongusername

  What are the purposes of having private/protected members of a class/structure in object-oriented programming? What's the harm in having all members be public?

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• How can ported code be detected?

  - by NiallJG

  If you port code over from one language to another, how can this be detected? Say you were porting code from c++ to Java, how could you tell? What would be the difference between a program designed and implemented in Java, and a near identical program ported over to Java?

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• Getting a char array from a vector<int>?

  - by Legend

  I am trying to pass a value from C++ to TCL. As I cannot pass pointers without the use of some complicated modules, I was thinking of converting a vector to a char array and then passing this as a null terminated string (which is relatively easy). I have a vector as follows: 12, 32, 42, 84 which I want to convert into something like: "12 32 42 48" The approach I am thinking of is to use an iterator to iterate through the vector and then convert each integer into its string representation and then add it into a char array (which is dynamically created initially by passing the size of the vector). Is this the right way or is there a function that already does this?

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