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• MVC and Checkboxes...leaves a bit to be desired

  - by Josh

  Here is my problem. I have a list of models that are displayed to the user. On the left is a checkbox for each model to indicate that the user wants to choose this model (in this case, we're building products a user can add to their shopping cart). The model has no concept of being chosen...it strictly has information about the product in question. I've talked with a few other developers after having gone through and the best I could come up with is getting the formcollection and string parsing the key values to determine whether the checkbox is checked or not. This doesn't seem ideal. I was thinking there would be something more strongly bound, but I can't figure out a way to do it. I tried creating another model that had a boolean property to represent being checked and a property of the model and passing a list of that model type to the view and creating a ActionResult on the controller that accepts a list of the new model / checked property, but it comes back null. Am I just thinking too much like web forms and should just continue on with parsing checkbox values?

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• selective UnknownHostException

  - by Stephan

  Hi everybody! I am getting said Exception in my program, but only in certain cases. First of all, I have the internet permission set:<uses-permission android:name="android.permission.INTERNET" />, and I tried the two method of this and this thread (they don't work in my case). The scenario is the following: I send a GET request to a rest service (e.g. http://my.web.site/request.php?attr=blah) and I do get a correct xml back. Now, in this xml there are some resources described, one of which is an url to an image (e.g http://my.web.site/images/img.jpg). Here it's where it fails! Here I consistently receive a UnknownHostException. I find it weird, since it's the same domain and everything. Accessing the img url from browser works (both from the emulator browser and pc browser). I tried from a device too but it doesn't get the image anyway. Any idea on why this weird behavior? EDIT: all my tests were on emulator and device, but connected to a wifi network. I tried also using the internet connection of my provider on the phone (i.e. bypassing home network), and still the behavior is the same... I found this bug which I assume is the source of this problem, but still no solution (after more than 1.5years). Any ideas?

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• Write a completely fluid HTML page (using '%' instead of 'px' for EVERY element height/width)

  - by barak manos

  I am designing my HTML pages to be completely fluid: For every element in the mark-up (HTML), I am using 'style="height:%;width:%"' (instead of 'style="height:*px;width:*px"'). This approach seems to work pretty well, except for when changing the window measurements, in which case, the web page elements change their position and end up "on top of each other". I have come up with a pretty good run-time (java-script) solution to that: var elements = document.getElementsByTagName("*"); for (var i=0; i < elements.length; i++) { if (elements[i].style.height) elements[i].style.height = elements[i].offsetHeight+"px"; if (elements[i].style.width ) elements[i].style.width = elements[i].offsetWidth +"px"; } The only problem remaining is, that if the user opens up the website by entering the URL into a non-maximized window, then the page fits that portion of the window. Then, when maximizing the window, the page remains in its previous measurements. So in essence, I have solved the initial problem (when changing the window measurements), but only when the window is initially in its maximum size. Any ideas on how to tackle this problem? (given that I would like to keep my "% page-design" as is).

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• What is the best way to create a running integer id on the AppEngine data storage?

  - by Freed

  For various reasons, I need a unique running integer id for my entities stored on the Google AppEngine. The automatically generated key sort of has this behaviour, but it doesn't start from 1 (or 0) and doesn't guarantee that the generated integer part will come from a continuous sequence. What would be the best way to efficiently implement this on AppEngine? Is there any support from the storage system? To add to the complexity, I might need to do this over entities from different entity groups, meaning I can't just get the highest id right now and save an entity with the next id in a transaction. Might memcache be the way to go..? Edit: I havn't yet implemented this, but to clarify on the memcache idea. I know memcache is unreliable, but in practice it probably won't lose data "too often" to hurt performance. Basically, I would have a memcache entry for the last used id, update it (somehow atomically) whenever I create a new entity and use that id. In the case of memcache not having a value for this entry, I'd get the highest id so far by doing a query on my entities sorted by the id and update memcache (unless someone else had already done so). The only problem I can see with this right now would be atomicity of the operation as a whole if the save of my new entity was also part of a transaction. Thoughts..?

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• Manipulating data in sql / asp.net / c# - how?

  - by SLC

  Not sure how to word the question... Basically, so far all my SQL stuff has been stored procedures and dumped into a gridview. The odd case where I had to perform an action based on a value (such as highlighting a row green if a certain value was true) were done as the gridview was rendering in one of the overrides. Now however I have to do something far more complicated - pull three sets of data down, run a series of checks on all three and some date related checks and stuff, then populate a gridview with some of the items. In logic terms, I want to run three queries, and store the lists of results (presumably in Lists?) then run some logic, then populate the gridview. Specifically what I don't know how to do is: Best way of pulling the data, and putting it into a List or other datastructure that lets me easily run through it, and retrieve data based on column (myList.age, or more likely, myList["Age"]). One I have compared the data, I assume I create a new list that will be put into the gridview... how do I put the contents of a list INTO a gridview? How would I add other stuff such as buttons or checkboxes at the same time? Any nudge in the right direction would be appreciated! Particularly doing cool stuff with lists and sql (if there is anything cool you can do with them)

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• SQL Server 2008 - Update a temporary table

  - by user336786

  Hello, I have stored procedure in which I am trying to retrieve the last ticket completed by each user listed in a comma-delimited string of usernames. The user may not have a ticket associated with them, in this case I know that i just need to return null. The two tables that I am working with are defined as follows: User ---- UserName, FirstName, LastName Ticket ------ ID, CompletionDateTime, AssignedTo, AssignmentDate, StatusID TicketStatus ------------ ID, Comments I have created a stored procedure in which I am trying to return the last completed ticket for a comma-delimited list of usernames. Each record needs to include the comments associated with it. Currently, I'm trying the following: CREATE TABLE #Tickets ( [UserName] nvarchar(256), [FirstName] nvarchar(256), [LastName] nvarchar(256), [TicketID] int, [DateCompleted] datetime, [Comments] text ) -- This variable is actually passed into the procedure DECLARE @userList NVARCHAR(max) SET @userList='user1,user2,user2' -- Obtain the user information for each user INSERT INTO #Tickets ( [UserName], [FirstName], [LastName] ) SELECT u.[UserName], u.[FirstName], u.[LastName] FROM User u INNER JOIN dbo.ConvertCsvToTable(@userList) l ON u.UserName=l.item At this point, I have the username, first and last name for each user passed in. However, I do not know how to actually get the last ticket completed for each of these users. How do I do this? I believe I should be updating the temp table I have created. At the same time, id do not know how to get just the last record in an update statement. Thank you!

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• Using Javascript to get URL Vars, not working when multiple values present in QueryString

  - by bateman_ap

  Hi, I am using a Javascript function to get the values of a URL to pass to jQuery using the function below: function getUrlVars() { var vars = [], hash; var hashes = window.location.href.slice(window.location.href.indexOf('?') + 1).split('&'); for(var i = 0; i < hashes.length; i++) { hash = hashes[i].split('='); vars.push(hash[0]); vars[hash[0]] = hash[1]; } return vars; } And then setting the value like this: var type = getUrlVars()["type"] This all works perfectly, however I have just come into a situation where I need to get multiple values, one of my form elements are checkboxes where multiple values can be checked, so my URL will look something like this: http://www.domain.com/test.php?type=1&cuisine[]=23&cuisine[]=43&name=test If I alert out the cuisine value using the function above I only ever get the final value: alert (getUrlVars()["cuisine[]"]); Would alert "43". What I would like it to be is a comma delimited string of all "cuisine" values. ie in the above example "23,43" Any help very welcome! In case any solution requires it I am using PHP 5.3 and Jquery 1.4

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• Why does defined(X) not work in a preprocessor definition without a space?

  - by Devin

  A preprocessor definition that includes defined(X) will never evaluate to true, but (defined X) will. This occurs in MSVC9; I have not tested other preprocessors. A simple example: #define FEATURE0 1 #define FEATURE1 0 #define FEATURE2 1 #define FEATURE3 (FEATURE0 && !FEATURE1 && (defined(FEATURE2))) #define FEATURE4 (FEATURE0 && !FEATURE1 && (defined FEATURE2)) #define FEATURE5 (FEATURE0 && !FEATURE1 && (defined (FEATURE2))) #if FEATURE3 #pragma message("FEATURE3 Enabled") #elif (FEATURE0 && !FEATURE1 && (defined(FEATURE2))) #pragma message("FEATURE3 Enabled (Fallback)") #endif #if FEATURE4 #pragma message("FEATURE4 Enabled") #elif (FEATURE0 && !FEATURE1 && (defined FEATURE2)) #pragma message("FEATURE4 Enabled (Fallback)") #endif #if FEATURE5 #pragma message("FEATURE5 Enabled") #elif (FEATURE0 && !FEATURE1 && (defined (FEATURE2))) #pragma message("FEATURE5 Enabled (Fallback)") #endif The output from the compiler is: 1FEATURE3 Enabled (Fallback) 1FEATURE4 Enabled 1FEATURE5 Enabled Working cases: defined (X), defined( X ), and defined X. Broken case: defined(X) Why is defined evaluated differently when part of a definition, as in the #if cases in the example, compared to direct evaluation, as in the #elif cases in the example?

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• More than one unique key for HashMap problem (Java)

  - by Alex Cheng

  This question is a continuation of this thread: In short: To solve my problem, I want to use Map<Set<String>, String>. However, after I sort my data entries in Excel, remove the unnecessary parameters, and the following came out: flow content ==> content content flow content ==> content depth distance flow content ==> content depth within flow content ==> content depth within distance flow content ==> content within flow content ==> content within distance I have more than one unique key for the hashmap if that is the case. How do I go around this... anyone have any idea? I was thinking of maybe Map<Set <String>, List <String>> so that I can do something like: Set <flow content>, List <'content content','content depth distance','content depth within ', ..., 'content within distance'> But because I am parsing the entries line by line I can't figure out the way how to store values of the same repeated keys (flow content) into the same list and add it to the map. Anyone have a rough logic on how can this be done in Java? Thanks in advance.

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• Is there a unique computer identifier that can be used reliably even in a virtual machine?

  - by SaUce

  I'm writing a small client program to be run on a terminal server. I'm looking for a way to make sure that it will only run on this server and in case it is removed from the server it will not function. I understand that there is no perfect way of securing it to make it impossible to ran on other platforms, but I want to make it hard enough to prevent 95% of people to try anything. The other 5% who can hack it is not my concern. I was looking at different Unique Identifiers like Processor ID, Windows Product ID, Computer GUID and other UIs. Because the terminal server is a virtual machine, I cannot locate anything that is completely unique to this machine. Any ideas on what I should look into to make this 95% secure. I do not have time or the need to make it as secure as possible because it will defeat the purpose of the application itself. I do not want to user MAC address. Even though it is unique to each machine it can be easily spoofed. As far as Microsoft Product ID, because our system team clones VM servers and we use corporate volume key, I found already two servers that I have access to that have same Product ID Number. I have no Idea how many others out there that have same Product ID By 95% and 5% I just simply wanted to illustrate how far i want to go with securing this software. I do not have precise statistics on how many people can do what. I believe I might need to change my approach and instead of trying to identify the machine, I will be better off by identifying the user and create group based permission for access to this software.

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• Need help to solve sharedPreference probem

  - by HFherasen

  I am working on this app where I have one EditText field where you can write somthing and then it get saved and added to a list(TextView). I save the content of the EditText in this way : saved += "*" + editTextFelt.getText().toString() + ". \n"; saved is a String. Everything works fine, I can even reload the app and it's still displayed in the TextView, but if i try to write somthing and save it everything that was there, now dissapear. anyone know why ? It's kind of confusing, and I have to get it to work! Thank's!! CODE: init Mehtod() sp = getSharedPreferences(fileName, 0); betaView = (TextView)findViewById(R.id.betaTextView); Ive got a button to send the text, and this is like: p ublic void onClick(View v) { switch(v.getId()){ case R.id.btnSend: saved += "*" + editTextFelt.getText().toString() + ". \n"; SharedPreferences.Editor editor = sp.edit(); editor.putString("SAVED", saved); editor.commit(); betaView.setText(sp.getString("SAVED", "Empty"));

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• Intelligently removing excess indention from a string

  - by TravisO

  I'm trying to remove some excessive indention from a string, in this case it's SQL, so it can be put into a log file. So I need the find the smallest amount of indention (aka tabs) and remove it from the front of each line, but the following code ends up printing out exactly the same, any ideas? In other words, I want to take the following SELECT blah FROM table WHERE id=1 and convert it to SELECT blah FROM table WHERE id=1 here's the code I tried and fails $sql = ' SELECT blah FROM table WHERE id=1 '; // it's most likely idented SQL, remove any idention $lines = explode("\n", $sql); $space_count = array(); foreach ( $lines as $line ) { preg_match('/^(\t+)/', $line, $matches); $space_count[] = strlen($matches[0]); } $min_tab_count = min($space_count); $place = 0; foreach ( $lines as $line ) { $lines[$place] = preg_replace('/^\t{'. $min_tab_count .'}/', '', $line); $place++; } $sql = implode("\n", $lines); print '<pre>'. $sql .'</pre>';

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• ASP.NET configuration inheritance

  - by NowYouHaveTwoProblems

  I have an ASP.NET application that defines a custom configuration section in web.config. Recently I had a customer who wanted to deploy two instances of the application (for testing in addition to an existing production application). The configuration chosen by the customer was: foo.com - production application foo.com/Testing - test application In this case, the ASP.NET configuration engine decided to apply the settings at foo.com/web.config to foo.com/Testing/web.config. Thankfully this caused a configuration error because the section was redefined at the second level rather than giving the false impression that the two web applications were isolated. What I would like to do is to specify that my configuration section is not inherited and must be re-defined for any web application that requires it but I haven't been able to find a way to do this. My web.config ends up something like this <configuration> <configSections> <section name="MyApp" type="MyApp.ConfigurationSection"/> </configSections> <MyApp setting="value" /> <NestedSettingCollection> <Item key="SomeKey" value="SomeValue" /> <Item key="SomeOtherKey" value="SomeOtherValue" /> </NestedSettingCollection> </MyApp> </configuration>

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• php validate integer [updated]

  - by George Garchagudashvili

  Read B A: I'll give quick example: $a = "\n \t 34 3"; // string(9) $aint = intval($a); // int(34) var_dump($a == $aint); result: bool(true) call me noob but can you tell me why/how does these variables do pass equalization test? What I want to achieve is to check if '1989' equals 1989 would be true, but not any other case. ex: '1989 ' should not pass the test. Also I don't want to use regex. B: I need to validate if variable is integer, I've tried all the available built-in functions or helpful tips, but the only best solution would be regex which I don't want to use this time. also filter_var is not best because it also filters data, but I want to only validate it. 123 -123 '123' '-123' these inputs to be only true, false otherwise I've tried many different options: ctype_digit("-123"); // false - doesn't work is_int('123'); // false filter_var(' 123 ', FILTER_VALIDATE_INT) !== false; // true - doesn't work

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• Mysterious combination

  - by pstone

  I decided to learn concurrency and wanted to find out in how many ways instructions from two different processes could overlap. The code for both processes is just a 10 iteration loop with 3 instructions performed in each iteration. I figured out the problem consisted of leaving X instructions fixed at a point and then fit the other X instructions from the other process between the spaces taking into account that they must be ordered (instruction 4 of process B must always come before instruction 20). I wrote a program to count this number, looking at the results I found out that the solution is n Combination k, where k is the number of instructions executed throughout the whole loop of one process, so for 10 iterations it would be 30, and n is k*2 (2 processes). In other words, n number of objects with n/2 fixed and having to fit n/2 among the spaces without the latter n/2 losing their order. Ok problem solved. No, not really. I have no idea why this is, I understand that the definition of a combination is, in how many ways can you take k elements from a group of n such that all the groups are different but the order in which you take the elements doesn't matter. In this case we have n elements and we are actually taking them all, because all the instructions are executed ( n C n). If one explains it by saying that there are 2k blue (A) and red (B) objects in a bag and you take k objects from the bag, you are still only taking k instructions when 2k instructions are actually executed. Can you please shed some light into this? Thanks in advance.

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• Enums and inheritance

  - by devoured elysium

  I will use (again) the following class hierarchy: Event and all the following classes inherit from Event: SportEventType1 SportEventType2 SportEventType3 SportEventType4 I have originally designed the Event class like this: public abstract class Event { public abstract EventType EventType { get; } public DateTime Time { get; protected set; } protected Event(DateTime time) { Time = time; } } with EventType being defined as: public enum EventType { Sport1, Sport2, Sport3, Sport4 } The original idea would be that each SportEventTypeX class would set its correct EventType. Now that I think of it, I think this approach is totally incorrect for two reasons: If I want to later add a new SportEventType class I will have to modify the enum If I later decide to remove one SportEventType that I feel I won't use I'm also in big trouble with the enum. I have a class variable in the Event class that makes, afterall, assumptions about the kind of classes that will inherit from it, which kinda defeats the purpose of inheritance. How would you solve this kind of situation? Define in the Event class an abstract "Description" property, having each child class implement it? Having an Attribute(Annotation in Java!) set its Description variable instead? What would be the pros/cons of having a class variable instead of attribute/annotation in this case? Is there any other more elegant solution out there? Thanks

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• Watching variables in SSIS during debug

  - by Tom H.

  I have a project in SSIS and I've added an Execute SQL Task which sends its result out to a variable. I wanted to confirm the value because I was worried that it would try to write it out as a resultset object rather than an actual integer (in this case I'm returning a COUNT). My first thought was just to run it in debug mode and add the global variable to my Watch window. Unfortunately, when I right-click on the Watch window, the option to "Add Variable" is greyed out. What am I missing here? I've gotten around confirming that my variable is set correctly, so I'm not interested in methods like putting a script in to do a MsgBox with the value or anything like that. For future reference I'd like to be able to watch variables in debug mode. If there are some kind of constraints on that then I'd like to know the what and why of it all if anyone knows. The help is woefully inadequate on this one and every "tutorial" that I can find just says, "Add the variable to the Watch window and debug" as though there should never be a problem doing that. Thanks for any insight!

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• rails route question

  - by badnaam

  I am trying to build a search functionality which at a high level works like this. 1 - I have a Search model, controller with a search_set action and search views/partial to render the search. 2 - At the home page a serach form is loaded with an empty search object or a search object initialized with session[:search] (which contains user search preferences, zip code, proximity, sort order, per page etc). This form has a post(:put) action to search_set. 3 - When a registered user performs a set the params of the search form are collected and a search record is saved against that user. If a unregistered user performs a search then the search set action simply stores the params in the session[:search]. In either case, the search is executed with the given params and the results are displayed. At this point the url of in the location bar is something like.. http://localhost:3000/searches/search_set?stype=1 At this point if the user simply hits enter on the location bar, I get an error that says "No action responded to show" I am guessing because the URL contains search_set which uses a put method and even though I have a search_show (:get) action (which simply reruns the search in the session or saved in the database) does not get called. How can I handle this situation where I can route a user hitting enter into the location bar to a get method? If this does not explain the problem , please let me know I can share more details/code etc. Thanks!

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• form_form and custom parameter in path_prefix

  - by fguillen

  Hi people, I have this route: # config/routes.rb map.namespace :backshop, :path_prefix => '/:shop_id/admin' do |backshop| backshop.resources :items end And I want to use the form_for magic to reuse the same form on both: new and edit views: <% form_for [:backshop, @item] do |f| %> This used to works, and used to build a create url for the item or update url for the item depending on the status of the @item object. But this is not working on this case because the routes don't exists without the shop_id parameter, and I don't know how to say to the form_for something like this: <% form_for [:backshop, @item], :shop_id => @shop do |f| %> Because it tries to use the @item like the :shop_id parameter. Or like this <% form_for [:backshop, @shop, @item] do |f| %> Because it tries to build this url: backshop_shop_order_path I Know I can just to extract the form_for declaration from the partial and do different calls on depending if new or edit: <% form_for( @item, :url => backshop_items_path( @shop ) ) do |f| %> and <% form_for( @item, :url => backshop_item_path( @shop, @item ) ) do |f| %> But I just wanted don't do this because I have a bunch of models and is a few boring :) Thanks for any suggestion f.

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• Set all nonzero matrix elements to 1 (while keeping the others 0)

  - by Tomas Lycken

  I have a mesh grid defined as [X, Y, Z] = meshgrid(-100:100, -100:100, 25); % z will have more values later and two shapes (ovals, in this case): x_offset_1 = 40; x_offset_2 = -x_offset_1; o1 = ((X-x_offset_1).^2./(2*Z).^2+Y.^2./Z.^2 <= 1); o2 = ((X-x_offset_2).^2./(2*Z).^2+Y.^2./Z.^2 <= 1); Now, I want to find all points that are nonzero in either oval. I tried union = o1+o2; but since I simply add them, the overlapping region will have a value of 2 instead of the desired 1. How can I set all nonzero entries in the matrix to 1, regardless of their previous value? (I tried normalized_union = union./union;, but then I end up with NaN in all 0 elements because I'm dividing by zero...) Follow-up question: I got a perfect answer to my original question, but now I have a follow-up question on the same problem. I'm going to define a filled disc, c = (X.^2+Y.^2<R^2) that will also overlap with the two ovals. How do I find all the points that are inside the circle, but not inside any of the ovals?

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• generate k distinct number less then n

  - by davit-datuashvili

  hi i have following question task is this generate k distinct positive numbers less then n without duplication my method is following first create array size of k where we should write these numbers int a[]=new int[k]; //now i am going to cretae another array where i check if (at given number position is 1 then generate number again else put this number in a array and continue cycle i put here a piece of code and explanations int a[]=new int[k]; int t[]=new int[n+1]; Random r=new Random(); for (int i==0;i<t.length;i++){ t[i]=0;//initialize it to zero } int m=0;//initialize it also for (int i=0;i<a.length;i++){ m=r.nextInt(n);//random element between 0 and n if (t[m]==1){ //i have problem with this i want in case of duplication element occurs repeats this steps afain until there will be different number else{ t[m]=1; x[i]=m; } } so i fill concret my problem if t[m]==1 it means that this element occurs already so i want to generate new number but problem is that number of generated numbers will not be k beacuse if i==0 and occurs duplicate element and we write continue then it will switch at i==1 i need like goto for repeat step or for (int i=0;i<x.length;i++){ loop: m=r.nextInt(n); if ( x[m]==1){ continue loop; } else{ x[m]=1; a[i]=m; continue;//continue next step at i=1 and so on } } i need this code in java please help

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• Generating all unique crossword puzzle grids

  - by heydenberk

  I want to generate all unique crossword puzzle grids of a certain grid size (4x4 is a good size). All possible puzzles, including non-unique puzzles, are represented by a binary string with the length of the grid area (16 in the case of 4x4), so all possible 4x4 puzzles are represented by the binary forms of all numbers in the range 0 to 2^16. Generating these is easy, but I'm curious if anyone has a good solution for how to programmatically eliminate invalid and duplicate cases. For example, all puzzles with a single column or single row are functionally identical, hence eliminating 7 of those 8 cases. Also, according to crossword puzzle conventions, all squares must be contiguous. I've had success removing all duplicate structures, but my solution took several minutes to execute and probably was not ideal. I'm at something of a loss for how to detect contiguity so if anyone has ideas on this it'd be much appreciated. I'd prefer solutions in python but write in whichever language you prefer. If anyone wants, I can post my python code for generating all grids and removing duplicates, slow as it may be.

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• How to make Finder 'Open With' work for my application (XCode, OS X)?

  - by Adion

  I have created an application that is capable of playing audio files. This in itself works fine, and so does drag&drop from finder to my application. What I would like as well, is that people can use my application from Finder using the Open With menu (or even allow them to set my application as default for a certain file type) After a lot of searching, I found that I should configure a document type in XCode (Editing information property lists) I successfully added such a type named 'Music File', with UTI 'public.mp3' When I now right-click an MP3 file, my application is listed in the 'Open With' menu. Trying to use it, my app opens, but I get a warning message saying "The document could not be opened. App cannot open files in the 'Music File' format" It doesn't appear to be passed through the command line as is the case in Windows. My application does support drag&drop from Finder, and this is working fine too. I don't really know where to look next, so it would be great if anyone could point me in the right direction. My application isn't using NSDocument, so the 'Class' field doesn't apply for me I think (and according to the docs this field isn't required, but it doesn't say how to handle it without a Class)

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• determining the starting speed for an accelerated animation (in flash/actionscript but it's a math question)

  - by vulkanino

  This question burns my brain. I have an object on a plane, but for the sake of simplicity let's work just on a single dimension, thus the object has a starting position xs. I know the ending position xe. The object has to move from starting to ending position with an accelerated (acceleration=a) movement. I know the velocity the object has to have at the ending position (=ve). In my special case the ending speed is zero, but of course I need a general formula. The only unknown is the starting velocity vs. The objects starts with vs in xs and ends with ve in xe, moving along a space x with an acceleration a in a time t. Since I'm working with flash, space is expressed in pixels, time is expressed in frames (but you can reason in terms of seconds, it's easy to convert knowing the frames-per-second). In the animation loop (think onEnterFrame) I compute the new velocity and the new position with (a=0.4 for example): vx *= a (same for vy) x += vx (same for y) I want the entire animation to last, say, 2 seconds, which at 30 fps is 60 frames. Now you know that in 60 frames my object has to move from xs to xe with a constant deceleration so that the ending speed is 0. How do I compute the starting speed vs? Maybe there's a simpler way to do this in Flash, but I am now interested in the math/physics behind this.

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• Java: GatheringByteChannel advantages?

  - by Jason S

  I'm wondering when the GatheringByteChannel's write methods (taking in an array of ByteBuffers) have advantages over the "regular" WritableByteChannel write methods. I tried a test where I could use the regular vs. the gathering write method on a FileChannel, with approx 400KB/sec total in ByteBuffers of between 23-27 bytes in length in both cases. Gathering writes used an array of 64. The regular method used up approx 12% of my CPU, and the gathering method used up approx 16% of my CPU (worse than the regular method!) This tells me it's NOT useful to use gathering writes on a FileChannel around this range of operating parameters. Why would this be the case, and when would you ever use GatheringByteChannel? (on network I/O?) Relevant differences here: public void log(Queue<Packet> packets) throws IOException { if (this.gather) { int Nbuf = 64; ByteBuffer[] bbufs = new ByteBuffer[Nbuf]; int i = 0; Packet p; while ((p = packets.poll()) != null) { bbufs[i++] = p.getBuffer(); if (i == Nbuf) { this.fc.write(bbufs); i = 0; } } if (i > 0) { this.fc.write(bbufs, 0, i); } } else { Packet p; while ((p = packets.poll()) != null) { this.fc.write(p.getBuffer()); } } }

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