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• What is Restful Routing?

  - by John Baker

  I have been searching pretty hard for info out on the net to explain exactly what Restful routing is but I haven't had any success. There are a lot of resources but not a who lot make sense to me. I'm familiar with Ruby On Rails's routing system and well as how Code Igniter and PhpCake route things but is there more to it than having a centralized location where you give out routes based on a directory structure? Like this: controller/action/id/ Admin/editUser/22 I'd appreciate any help with this, it's had me baffled for months. I just thought of putting it on SO. Thanks

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• Behavior of nested finally in Exceptions

  - by kuriouscoder

  Hello: Today at work, I had to review a code snippet that looks similar to this mock example. package test; import java.io.IOException; import org.apache.log4j.Logger; public class ExceptionTester { public static Logger logger = Logger.getLogger(ExceptionTester.class); public void test() throws IOException { new IOException(); } public static void main(String[] args) { ExceptionTester comparator = new ExceptionTester(); try { try { comparator.test(); } finally { System.out.println("Finally 1"); } } catch(IOException ex) { logger.error("Exception happened" ex); // also close opened resources } System.out.println("Exiting out of the program"); } } It's printing the following output.I expected an compile error since the inner try did not have a catch block. Finally 1 Exiting out of the program I do not understand why IOException is caught by the outer catch block. I would appreciate if anyone can explain this, especially by citing stack unwinding process

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• C++ Pointers to functions.

  - by Andy Leman

  using namespace std; int addition (int a, int b) { return (a+b); } int subtraction (int a, int b) { return (a-b); } int operation (int x, int y, int (*functocall)(int,int)) { int g; g = (*functocall)(x,y); return(g); } int main() { int m,n; int (*minus)(int,int) = subtraction; m = operation (7,5,addition); n = operation (20,m,minus); cout << n; return 0; } Can anybody explain this line for me int (*minus)(int,int) = subtraction; Thanks a lot!

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• MySQL - Conflicting WHERE and GROUP BY Statements

  - by TaylorPLM

  I have a query returning the counts of some data, but I do NOT want data that has a null value in it... As an example, the code rolls stats from a clicking system into a table. SELECT sh.dropid, ... FROM subscriberhistory sh INNER JOIN subscriberhistory sh2 on sh.subid = sh2.subid WHERE sh.dropid IS NOT NULL AND sh.dropid != "" ... GROUP BY sh.dropid An example of the record set returned would look like this... 400 2 3 4 5 6 401 2 3 6 5 4 NULL 2 3 4 5 1 There are some other where clauses, and a few more selects (as I said, using the count aggregate) that are also within the query. There is also an order by statement. Again, the goal is to keep the NULL data out of the preceding record set. Could someone explain to me why this behavior is occurring and what to do to solve it.

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• asynchronous writing and reading of a file

  - by tazim

  hi, I have two processes. 1.) One processes is redirecting output of some unix command to a file on server side.the data is always appended to the file eg : find / > tmp.txt 2.)Another process is opening and reading the same file and storing it in a string and sending the entire string to the client Now, this things take simultaneously. I am using python. Any suggestion as in what can be possible ways to implement this scenario . Please explain with sample code . Thanks in advance . Tazim.

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• Fault exception trashes a register causing a crash in [NSInvocation invoke]

  - by Mike Weller

  I have an NSOperation which fetches some objects from a core data persistent store and sums up a few totals. Sometimes an object is deleted while the operation in in progress, so a core data fault exception occurs. I try/catch the exception while summing to ignore it because I just want to skip objects that cannot be faulted in. However, when one of these fault exceptions occurs (and I swallow it) there is a crash after the invocation returns in [NSInvocation invoke]. It's a bad memory access when dereferencing the value in r10 which according to GDB on a successful run points to one of these: (gdb) x 0x38388348 0x38388348 <OBJC_IVAR_$_NSInvocation._retdata>: 0x00000008 If a fault exception occured a value of 0x02 is in the register which causes the crash. A quick google search tells me that r10 should be saved by the callee, meaning it is not being restored by whatever code is changing it when this exception occurs. Can anybody explain this? I'm not an expert when it comes to these kinds of low-level details

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• Why does PHP 5.2 disallow abstract static class methods?

  - by Artem Russakovskii

  After enabling strict warnings in PHP 5.2, I saw a load of strict standards warnings from a project that was originally written without strict warnings: Strict Standards: Static function Program::getSelectSQL() should not be abstract in Program.class.inc The function in question belongs to an abstract parent class Program and is declared abstract static because it should be implemented in its child classes, such as TVProgram. I did find references to this change here: Dropped abstract static class functions. Due to an oversight, PHP 5.0.x and 5.1.x allowed abstract static functions in classes. As of PHP 5.2.x, only interfaces can have them. My question is: can someone explain in a clear way why there shouldn't be an abstract static function in PHP?

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• Why is Postgres doing a Hash in this query?

  - by Claudiu

  I have two tables: A and P. I want to get information out of all rows in A whose id is in a temporary table I created, tmp_ids. However, there is additional information about A in the P table, foo, and I want to get this info as well. I have the following query: SELECT A.H_id AS hid, A.id AS aid, P.foo, A.pos, A.size FROM tmp_ids, P, A WHERE tmp_ids.id = A.H_id AND P.id = A.P_id I noticed it going slowly, and when I asked Postgres to explain, I noticed that it combines tmp_ids with an index on A I created for H_id with a nested loop. However, it hashes all of P before doing a Hash join with the result of the first merge. P is quite large and I think this is what's taking all the time. Why would it create a hash there? P.id is P's primary key, and A.P_id has an index of its own.

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• Unreachable, existing variable

  - by Oden

  I'm new at as3, maybe thats the reason why i don't understand, why the setInterval causes an error. <mx:Script> <![CDATA[ import flash.utils.setInterval; import mx.controls.Alert; [Bindable] public var MyInt:int = 500; setInterval(function():void{ ++MyInt; },1000); ]]> </mx:Script> I have a label where the value of MyInt gets visible, the bind works perfect, i've tested it several ways, and i i create a button it grows the number, but if i use the setInterval function i get an error: Access of undefined property myInt. Why? What does cause this? Please explain it, so I can avoid errors like this. Thanks

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• I can't Distinct, Sum, or Count from 3 tables with group clauses

  - by Rio Inggit Dharmawangsa

  I'm still learning linq, now i'm getting confused. I need data for report from 3 tables, I get the result, but it's duplicate. I have used distinct but it's not working, n I need data to be sum still not working. Here is my query, can somebody explain what's wrong? var report= (from u in myDb.TBL_TRANSAKSI_MKN_MNMs.AsEnumerable() where u.TGL_TRANSAKSI.Value.Date.Equals(dateTimePicker1.Value.Date) join l in myDb.TBL_DETAIL_TRANSAKSIs.AsEnumerable() on u.ID_NOTA equals l.ID_NOTA join m in myDb.TBL_MKN_MNMs.AsEnumerable() on l.ID_MKN_MNM equals m.ID_MKN_MNM group new { u, l, m } by new { m.NAMA_MKN_MNM, m.HARGA_JUAL, u.TGL_TRANSAKSI, l.ID_MKN_MNM, u.USERNAME, l.Jumlah } into grp select new { MakanMinum = grp.Key.NAMA_MKN_MNM, HargaJual = grp.Key.HARGA_JUAL, Stok = grp.Sum(groupedthing => groupedthing.l.Jumlah), Tanggal = grp.Key.TGL_TRANSAKSI, Jumlah =(grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)), Total = grp.Sum(grouptotal => grp.Key.HARGA_JUAL * grp.Sum(groupedthing => groupedthing.l.Jumlah)), Username = grp.Key.USERNAME }).Distinct();

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• Balanced Search Tree Query, Asymtotic Analysis..

  - by AGeek

  Hi, The situation is as follows:- We have n number and we have print them in sorted order. We have access to balanced dictionary data structure, which supports the operations serach, insert, delete, minimum, maximum each in O(log n) time. We want to retrieve the numbers in sorted order in O(n log n) time using only the insert and in-order traversal. The answer to this is:- Sort() initialize(t) while(not EOF) read(x) insert(x,t); Traverse(t); Now the query is if we read the elements in time "n" and then traverse the elements in "log n"(in-order traversal) time,, then the total time for this algorithm (n+logn)time, according to me.. Please explain the follow up of this algorithm for the time calculation.. How it will sort the list in O(nlogn) time?? Thanks.

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• Can C++ Constructors be templates?

  - by Gokul

  Hi, I have non-template class with a templatized constructor. This code compiles for me. But i remember that somewhere i have referred that constructors cannot be templates. Can someone explain whether this is a valid usage? typedef double Vector; //enum Method {A, B, C, D, E, F}; struct A {}; class Butcher { public: template <class Method> Butcher(Method); private: Vector a, b, c; }; template <> Butcher::Butcher(struct A) : a(2), b(4), c(2) { // a = 0.5, 1; // b = -1, 1, 3, 2; // c = 0, 1; } Thanks, Gokul.

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• question about c++ template functions taking any type as long that type meets at least one of the re

  - by smerlin

  Since i cant explain this very well, i will start with a small example right away: template <class T> void Print(const T& t){t.print1();} template <class T> void Print(const T& t){t.print2();} This does not compile: error C2995: 'void Print(const T &)' : function template has already been defined So, how can i create a template function which takes any type T as long as that type has a print1 memberfunction OR a print2 memberfunction (no polymorphism) ?

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• I know the big picture but can't put it in place

  - by Simbilim

  Hi, I'm interested in web development and by that I mean the bigger projects like facebook or twitter. I know the basics of java, css, php and mysql. I know there is a lot more out there. I read about it. But I don't know what the purpose is and how to put in place. Things like: Scribe, thrift, casandra, Unix/Linux, shell/perl/python scripting, PostgreSQL, MongoDB, non-relational NoSQL datastores, JVM, nginx I want to know why they need it, how they use it and what te purpose is. What I need is a book like technical background of facebook for dummies or so. Are there any books or websites that explain this from scratch? Thank you!

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• Django template tag basic question

  - by ninja123

  It looks like this template tag works like a charm for most people: http://blog.localkinegrinds.com/2007/09/06/digg-style-pagination-in-django/ For some reason I get this error: Caught an exception while rendering: 'is_paginated' I use this template tag in my template like so: {% load digg_paginator %} {% digg_paginator %} Where digg_paginator.py is in my app/templatetags folder and the included template context digg_paginator.html is in my app/templates folder. The queryset that needs pagination is called 'destinations'. If i just specify {% digg_paginator %}, how does it know what variable to paginate?? I feel I am missing something important here or just plain stupid :P Someone please help, or explain to me how this should be done. Thanks

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• How to convince a colleague that code duplication is bad?

  - by vitaut

  A colleague of mine was implementing a new feature in a project we work on together and he did it by taking a file containing the implementation of a similar feature from the same project, creating a copy of it renaming all the global declarations and slightly modifying the implementation. So we ended up with two large files that are almost identical apart from renaming. I tried to explain that it makes our project more difficult to maintain but he doesn't want to change anything saying that it is easier for him to program in such way and that there is no reason to fix the code if it "ain't broke". How can I convince him that such code duplication is a bad thing? It is related to this questions, but I am more interested in the answers targeted to a technical person (another programmer), for example a reference to an authoritative source like a book would be great. I have already tried simple arguments and haven't succeeded.

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• Initialising structs in C++

  - by Neil Butterworth

  As an addendum to this question, what is going on here: #include <string> using namespace std; struct A { string s; }; int main() { A a = {0}; } Obviously, you can't set a std::string to zero. Can someone provide an explanation (backed with references to the C++ Standard, please) about what is actually supposed to happen here? And then explain for example): int main() { A a = {42}; } Are either of these well-defined? Once again an embarrassing question for me - I always give my structs constructors, so the issue has never arisen before.

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• Any advice about how to make the design of an application.

  - by VansFannel

  Hello. I want to design an application and I don't know where to start. I know I can use UML to design the application, but I don't know the steps I must follow. I've started doing the UML class diagram, but I suppose, I'm been doing the database model, not the class model for the application. If I don't explain it well, tell me. Is there any tutorial about how to design an application? Thank you.

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• Sharing base object with inheritance

  - by max

  I have class Base. I'd like to extend its functionality in a class Derived. I was planning to write: class Derived(Base): def __init__(self, base_arg1, base_arg2, derived_arg1, derived_arg2): super().__init__(base_arg1, base_arg2) # ... def derived_method1(self): # ... Sometimes I already have a Base instance, and I want to create a Derived instance based on it, i.e., a Derived instance that shares the Base object (doesn't re-create it from scratch). I thought I could write a static method to do that: b = Base(arg1, arg2) # very large object, expensive to create or copy d = Derived.from_base(b, derived_arg1, derived_arg2) # reuses existing b object but it seems impossible. Either I'm missing a way to make this work, or (more likely) I'm missing a very big reason why it can't be allowed to work. Can someone explain which one it is? [Of course, if I used composition rather than inheritance, this would all be easy to do. But I was hoping to avoid the delegation of all the Base methods to Derived through __getattr__.]

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• Seeking free ODBC database optimization tool for non-experts

  - by mawg

  I'm a database n00b and am reading as many books as I can. I have been given responsibility for an ODBC tool where the databases were designed by a hardware engineer with some VB experience - which made him a s/w guru in the small firm at that time. Things are running slowly and I suspect that the db could have been designed better. I hope to learn enough to use Explain/Describe, etc maybe add some indices, but, in the meantime, is there any free for commercial use tool which can examine an ODBC database and suggest improvements. I'm just talking about db schema here, but maybe I should also be looking at optimizing Selects with Joins? Is there a tool for that? ODBC compliant.

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• class which cannot be derived

  - by benjamin button

  I found this code here class Usable; class Usable_lock { friend class Usable; private: Usable_lock() {} Usable_lock(const Usable_lock&) {} }; class Usable : public virtual Usable_lock { // ... public: Usable(); Usable(char*); // ... }; Usable a; class DD : public Usable { }; DD dd; // error: DD::DD() cannot access // Usable_lock::Usable_lock(): private member Could anybody explain me this code?

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• Java stop MIDI playback

  - by user456268

  Hi I have java application which plays midi messages from sequence. I'm doing this using jfugue library. the problem is when I'm tryingto stop playback with stop button (which call sequencer.stop() and sequencer.close()) the last played note is sound all of rest time, and I can't stop it. So I'm asking about solution about stopping all audio and MIDI too! sound playback from java application. Notice: If you want propose just mute volume, you need to know that I want end-use will be able to press play button again and hear the sound again, so muting volumr will be not a solution, or explain please. Thank you!

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• Multiple user database design

  - by dieguitoweb

  I have to develop a basic social network for an academic purpose; but I need some tips for the users management.. The users are subdivided into 3 groups with different privilege: admins,analysts and standards users. For every user should be stored into the database the following information: name,lastname,e-mail,age,password. I'm not quite sure how I should design the database between theese two solutions: 1)one table called 'users' with the 'role' attribute that explain what a user can do and what can't do, and the permissions are managed via php 2)every application user is a database user created with the query 'CREATE ROLE' (It's a postgres database) and he has permissions on some tables granted with the 'GRANT' statement You should take into account that the project is for a database exam.. thanks

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• Trouble using xib files in libraries

  - by flohei

  Hi there, I'm having some trouble working with libraries and included xib files. Let me explain my situation first. I've got a project that's running pretty good. Now I need a part of my project as a library for another customer who want's to use some of the functionality in his app. I've created a library with help of that highly recommended article. My customer should be able to initialize a main view controller like this: LibraryMainViewController *lmvc = [[LibraryMainViewController alloc] initWithNibName:@"LibraryMainViewController.xib" bundle:foo]; That for sure leads to an error when I try to present that view controller modally. I'm not sure what bundle I have to use here. I tried something like [NSBundle bundleForClass:[SomeClassInTheLibrary class]]; but that didn't solve the problem. I would be glad if someone could tell me how to actually use a xib file in that kind of situation. Thanks –f

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• Need help in downloading file with header() function

  - by riccardo

  Hi. I'm trying to explain as best as I can, sorry for my English. I have a list of links, each linked to a php file with an id by parameters (ex. download.php?id=1 or ?id=2 and so on). This file create a new instance of a class witch return the correct header of the files so it displays the save dialog box of the browser. Now I need to check if the files is already downloaded in past (The first time you downloaded it I add a field on the mysql db). This checks go ahead if you haven't download the files, else return false. Here is the problem, when it returns false or something else the browser redirect me to the download.php file, so I get a blank page or what I'm echoing. I need that if the file is already download it show me a js alert for advice ppl. Hope you can understand what i mean. Thanks for help

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