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• Parallel programming, are we not learning from history again?

  - by mezmo

  I started programming because I was a hardware guy that got bored, I thought the problems being solved in the software side of things were much more interesting than those in hardware. At that time, most of the electrical buses I dealt with were serial, some moving data as fast as 1.5 megabit!! ;) Over the years these evolved into parallel buses in order to speed communication up, after all, transferring 8/16/32/64, whatever bits at a time incredibly speeds up the transfer. Well, our ability to create and detect state changes got faster and faster, to the point where we could push data so fast that interference between parallel traces or cable wires made cleaning the signal too expensive to continue, and we still got reasonable performance from serial interfaces, heck some graphics interfaces are even happening over USB for a while now. I think I'm seeing a like trend in software now, our processors were getting faster and faster, so we got good at building "serial" software. Now we've hit a speed bump in raw processor speed, so we're adding cores, or "traces" to the mix, and spending a lot of time and effort on learning how to properly use those. But I'm also seeing what I feel are advances in things like optical switching and even quantum computing that could take us far more quickly that I was expecting back to the point where "serial programming" again makes the most sense. What are your thoughts?

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• How to set only the first cell of a UITableView to a different color?

  - by Ted

  I use cellForRowAtIndexPath like here: - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if(cell == nil) cell = [self getCellContentView:CellIdentifier]; UILabel *lbl = (UILabel*)[cell.contentView viewWithTag:1]; for (UITableViewCell *c in [tbl visibleCells]) { // UITableViewCell *cell2 = [tbl cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:0]]; UILabel *lbl = (UILabel*)[c.contentView viewWithTag:1]; lbl.textColor = [UIColor redColor]; } if([tbl indexPathForCell:cell].section==0) lbl.textColor = [UIColor whiteColor]; UILabel *lblTemp1 = (UILabel *)[cell viewWithTag:1]; UILabel *lblTemp2 = (UILabel *)[cell viewWithTag:2]; //First get the dictionary object lblTemp1.text = @"test!"; lblTemp2.text = @"testing more"; NSLog(@"%@",[tbl indexPathForCell:cell]); return cell; } But is still makes some of my cells white instead of gray. How can I change only the first item in the row to white?

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• Using unions to simplify casts

  - by Steven Lu

  I realize that what I am trying to do isn't safe. But I am just doing some testing and image processing so my focus here is on speed. Right now this code gives me the corresponding bytes for a 32-bit pixel value type. struct Pixel { unsigned char b,g,r,a; }; I wanted to check if I have a pixel that is under a certain value (e.g. r, g, b <= 0x10). I figured I wanted to just conditional-test the bit-and of the bits of the pixel with 0x00E0E0E0 (I could have wrong endianness here) to get the dark pixels. Rather than using this ugly mess (*((uint32_t*)&pixel)) to get the 32-bit unsigned int value, i figured there should be a way for me to set it up so I can just use pixel.i, while keeping the ability to reference the green byte using pixel.g. Can I do this? This won't work: struct Pixel { unsigned char b,g,r,a; }; union Pixel_u { Pixel p; uint32_t bits; }; I would need to edit my existing code to say pixel.p.g to get the green color byte. Same happens if I do this: union Pixel { unsigned char c[4]; uint32_t bits; }; This would work too but I still need to change everything to index into c, which is a bit ugly but I can make it work with a macro if i really needed to.

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• Linking Error Building 64bit Qt app on 32bit XP machine.

  - by photo_tom

  I'm trying to build a 64 bit version of my application (and yes I really do need the memory) on my 32bit xp dev box for production testing on our Vista64 server. Previously, I have built w/o any errors the Qt 4.6.2 DLL's in 64 bit mode. That step went vary smooth. Just to get started in building production, I'm trying to rebuild Qt's Star Delegate demo in 64bit mode. I converted the 32bit to 64bit app by changing the application configuration and adjusting the library's to the 64bit venisons. Now, when I go to link, I'm getting the following error when I link 1>------ Build started: Project: stardelegate, Configuration: Release x64 ------ 1>Linking... 1>MSVCRT.lib(crtexew.obj) : error LNK2001: unresolved external symbol WinMain 1>release64\stardelegate.exe : fatal error LNK1120: 1 unresolved externals Suggestions? edit - After some more searching, discovered if I link as a console app it will work and run. But not as a windows app. And I don't have this problem in 32 bit mode.

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• Select All in Javascript (Firefox extension) not working right

  - by leezer3

  I'm having some problems with a select all/ none function. (I didn't write it, I'm trying to fix it!) It currently looks like this: rsfindmod.SelAll = function(){ document.getElementById("ListBox").selectAll(); document.getElementById("ListBox").focus(); } It's being used on a dynamically generated set of links, so there's no set number of items in this listbox. This seems to work most of the time, but randomly it only selects those which are visible at the time. Scrolling the list or hitting the button again seems to normally make it work as expected. My first (Obvious?) thought was to replace the function entirely with the one from this link for testing: http://viralpatel.net/blogs/2009/06/listbox-select-all-move-left-right-up-down-javascript.html Trouble is that I can't get this one to work whatsoever! This gives me the error that listbox.options is not defined Any thoughts please? I'm by no means certain whether it's the original function at fault, or something in the generation of this listbox.

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• [RAILS] Why is ssl_requirement clearing the Flash? (Chrome Mac)

  - by aaronrussell

  I am using ssl_requirement and since setting it up, my application's Flash messages are disappearing. I've modified the plugin slightly as accounts can optionally have a domain mapped to their account. In that case the non-ssl areas of the site should use the mapped domain, whereas the ssl areas should use the subdomain: def ensure_proper_protocol return true if ssl_allowed? if ssl_required? && !request.ssl? redirect_to "https://#{@account.subdomain}." + APP_CONF[:domain] + request.request_uri flash.keep return false elsif request.ssl? && !ssl_required? redirect_to "http://#{@account.sub_or_mapped_domain}" + request.request_uri flash.keep return false end end The application is broadly split into a website (front end) and an admin (back end). ALL of the admin area uses SSL so in the AdminController I have overwritten ssl_required? with: protected def ssl_required? return false if RAILS_ENV == "test" || RAILS_ENV == "development" true end Interestingly, Flash messages work fine in the development environment, where I am bypassing requiring SSL, but in my production environment where SSL is required, all Flash are gone. Any ideas? EDIT I've done some further testing and can add that this problem is ONLY occurring in Chrome on the Mac. Other Mac browsers and Chrome on windows are displaying the Flash messages as expected. This may be a bug with Chrome on the Mac then...?

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• Receiving "expected expression before" Error When Using A Struct

  - by Zach Dziura

  I'm in the process of creating a simple 2D game engine in C with a group of friends at school. I'd like to write this engine in an Object-Oriented way, using structs as classes, function pointers as methods, etc. To emulate standard OOP syntax, I created a create() function which allocates space in memory for the object. I'm in the process of testing it out, and I'm receiving an error. Here is my code for two files that I'm using to test: test.c: #include <stdio.h> int main() { typedef struct { int i; } Class; Class *test = (Class*) create(Class); test->i = 1; printf("The value of \"test\" is: %i\n", test->i); return 0; } utils.c: #include <stdio.h> #include <stdlib.h> #include "utils.h" void* create(const void* class) { void *obj = (void*) malloc(sizeof(class)); if (obj == 0) { printf("Error allocating memory.\n"); return (int*) -1; } else { return obj; } } void destroy(void* object) { free(object); } The utils.h file simply holds prototypes for the create() and destroy() functions. When I execute gcc test.c utils.c -o test, I'm receiving this error message: test.c: In function 'main': test.c:10:32: error: expected expression before 'Class' I know it has something to do with my typedef at the beginning, and how I'm probably not using proper syntax. But I have no idea what that proper syntax is. Can anyone help?

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• How do I choose what and when to cache data with ob_start rather than query the database?

  - by Tim Santeford

  I have a home page that has several independent dynamic parts. The parts consist of a list of recent news from the company, a site statistics panel, and the online status of certain employees. The recent news changes monthly, site statistics change daily, and online statuses change on a per minute bases. I would like to cache these panels so that the db is not hit on every page load. Is using ob_start() then ob_get_contents() to cache these parts to a file the correct way to do this or is there a better method in PHP5 for doing this? In asking this question I'm trying to answer these additional questions: How can I determine the correct approach for caching this data without doing extensive benchmarking? Does it make sense to cache these parts in different files and then join them together per requests or should I re-query the data and cache once per minute? I'm looking for a rule of thumb for planning pages and for situations where doing testing is not cost effective (The client is not paying enough for it I mean). Thanks!

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• How do I manipulate the format on a DataGridView that is bound to a Data Source?

  - by Jack Johnstone

  I´m using SQL Server 2005 and Visual Studio 2008, C#. In the data source (the SQL Server data table) I use the DateTime format mm/dd/yyyy, however, in a forms overview (DataGridView) users would like to see a completely other format, with year, week number and day number of week (yyww,d) which is in string format. I´ve created an algorithm for the transformation between values (date to weekday), but can I populate the affected cells with yyww,d (string) instead of mm/dd/yyyy (DateTime)? This is what I´ve been testing out, without success (and note, it´s on the last line the problem becomes obvious, as the cell value won´t accept a string on runtime - it still wants to be a DateTime...) private void DataGridViewQueryFindRequests_CellFormatting( object sender, DataGridViewCellFormattingEventArgs e) { string weekAndDay = ""; DataGridViewCell cell = DataGridViewQueryFindRequests.Rows[e.RowIndex].Cells[e.ColumnIndex]; if (cell.ColumnIndex == 13 && cell.Value == null) mEmptyRow = true; if ((cell.ColumnIndex == 14 || cell.ColumnIndex == 15) && !mEmptyRow) { weekAndDay = ClassWeeksAndDates.dateToWeekNumber(Convert.ToDateTime(cell.Value)); cell.ValueType = typeof(string); cell.Value = weekAndDay; } }

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• Setting pixel values in Nvidia NPP ImageCPU objects?

  - by solvingPuzzles

  In the Nvidia Performance Primitives (NPP) image processing examples in the CUDA SDK distribution, images are typically stored on the CPU as ImageCPU objects, and images are stored on the GPU as ImageNPP objects. boxFilterNPP.cpp is an example from the CUDA SDK that uses these ImageCPU and ImageNPP objects. When using a filter (convolution) function like nppiFilter, it makes sense to define a filter as an ImageCPU object. However, I see no clear way setting the values of an ImageCPU object. npp::ImageCPU_32f_C1 hostKernel(3,3); //allocate space for 3x3 convolution kernel //want to set hostKernel to [-1 0 1; -1 0 1; -1 0 1] hostKernel[0][0] = -1; //this doesn't compile hostKernel(0,0) = -1; //this doesn't compile hostKernel.at(0,0) = -1; //this doesn't compile How can I manually put values into an ImageCPU object? Notes: I didn't actually use nppiFilter in the code snippet; I'm just mentioning nppiFilter as a motivating example for writing values into an ImageCPU object. The boxFilterNPP.cpp example doesn't involve writing directly to an ImageCPU object, because nppiFilterBox is a special case of nppiFilter that uses a built-in gaussian smoothing filter (probably something like [1 1 1; 1 1 1; 1 1 1]).

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• Adobe popping out of the browser

  - by Steven

  Hi, Im building a web application that displays a xfdf document. When we are testing in adobe 5 and we can't stop adobe opening outside the webpage. The user clicks the report and it should open in the browser but instead it opens in adobe it appears to work in everything but adobe 5. We have previously done this with out any problems. Any ideas? This is a snippet of the xfdf <?xml version="1.0" encoding="UTF-8" ?><xfdf xmlns="http://ns.adobe.com/xfdf/" xml:space="preserve"> <fields> <field name="fld_AccomAttic"> <value>0</value> </field> <field name="fld_AccomBathroom"> <value>1</value> </field> <field name="fld_AccomBedrooms"> <value>3</value> </field> <field name="fld_AccomCellars"> <value>0</value> </field> <field name="fld_AccomGarages"> <value>Off</value> </field><f href="{report name}"/></xfdf> Any help would be great Sp

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• Thread-Safe lazy instantiating using MEF

  - by Xaqron

  // Member Variable private static readonly object _syncLock = new object(); // Now inside a static method foreach (var lazyObject in plugins) { if ((string)lazyObject.Metadata["key"] = "something") { lock (_syncLock) { // It seems the `IsValueCreated` is not up-to-date if (!lazyObject.IsValueCreated) lazyObject.value.DoSomething(); } return lazyObject.value; } } Here I need synchronized access per loop. There are many threads iterating this loop and based on the key they are looking for, a lazy instance is created and returned. lazyObject should not be created more that one time. Although Lazy class is for doing so and despite of the used lock, under high threading I have more than one instance created (I track this with a Interlocked.Increment on a volatile static int and log it somewhere). The problem is I don't have access to definition of Lazy and MEF defines how the Lazy class create objects. I should notice the CompositionContainer has a thread-safe option in constructor which is already used. My questions: 1) Why the lock doesn't work ? 2) Should I use an array of locks instead of one lock for performance improvement ?

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• Prototype or jQuery for DOM manipulation (client-side dynamic content)

  - by luiggitama

  I need to know which of these two JavaScript frameworks is better for client-side dynamic content modification for known DOM elements (by id), in terms of performance, memory usage, etc.: Prototype's $('id').update(content) jQuery's jQuery('#id').html(content) BTW, both libraries coexist with no conflict in my app, because I'm using RichFaces for JSF development, that's why I can use "jQuery" instead of "$". I have at least 20 updatable areas in my page, and for each one I prepare content (tables, option lists, etc.), based on some user-defined client-side criteria filtering or some AJAX event, etc., like this: var html = []; int idx = 0; ... html[idx++] = '<tr><td class="cell"><span class="link" title="View" onclick="myFunction('; html[idx++] = param; html[idx++] = ')"></span>'; html[idx++] = someText; html[idx++] = '</td></tr>'; ... So here comes the question, which is better to use: // Prototype's $('myId').update(html.join('')); // or jQuery's jQuery('#myId').html(html.join('')); Other needed functions are hide() and show(), which are present in both frameworks. Which is better? Also I'm needing to enable/disable form controls, and to read/set their values. Note that I know my updatable area's id (I don't need CSS selectors at this point). And I must tell that I'm saving these queried objects in some data structure for later use, so they are requested just once when the page is rendered, like this: MyData = {div1:jQuery('#id1'), div2:$('id2'), ...}; ... div1.update('content 1'); div2.html('content 2'); So, which is the best practice?

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• Iterate over defined elements of a JS array

  - by sibidiba

  I'm using a JS array to Map IDs to actual elements, i.e. a key-value store. I would like to iterate over all elements. I tried several methods, but all have its caveats: for (var item in map) {...} Does iterates over all properties of the array, therefore it will include also functions and extensions to Array.prototype. For example someone dropping in the Prototype library in the future will brake existing code. var length = map.lenth; for (var i = 0; i < length; i++) { var item = map[i]; ... } does work but just like $.each(map, function(index, item) {...}); They iterate over the whole range of indexes 0..max(id) which has horrible drawbacks: var x = []; x[1]=1; x[10]=10; $.each(x, function(i,v) {console.log(i+": "+v);}); 0: undefined 1: 1 2: undefined 3: undefined 4: undefined 5: undefined 6: undefined 7: undefined 8: undefined 9: undefined 10: 10 Of course my IDs wont resemble a continuous sequence either. Moreover there can be huge gaps between them so skipping undefined in the latter case is unacceptable for performance reasons. How is it possible to safely iterate over only the defined elements of an array (in a way that works in all browsers and IE)?

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• Moving x,y position of all array objects every frame in actionscript 3?

  - by Dylan Gallardo

  I have my code setup so that I have an movieclip in my library a class called "block" being duplicated multiple times and added into an array like this: function makeblock(e:Event){ newblock=new block; newblock.x=10; newblock.y=10; addChild(newblock); myarray[counter] = newblock; //adds a newblock object into array counter += 1; } Then I have a loop with a currently primitive way of handling my problem: stage.addEventListener(Event.ENTER_FRAME, gameloop); function gameloop(evt:Event):void { if (moveright==true){ myarray[0].x += 5; myarray[1].x += 5; myarray[2].x += 5 -(and so on)- My question is how can I change x,y values every frame for new objects duplicated into the array, along with the previous ones that were added. Of course with a more elegant way than writing it out myself... array[0].x += 5, array[1], array[2], array[3] etc. Ideally I would like this to go up to 500 or more array objects for one array so obviously I don't want to be writing it out individually haha, I also need it to be consistent with performance so using a for loop or something to loop through the whole array and move each x += 5 wouldn't work would it? Anyway, if anyone has any ideas that'd be great!

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• What's the point of indicating AllowMultiple=false on an abstract Attribute class?

  - by tvanfosson

  On a recent question about MVC attributes, someone asked whether using HttpPost and HttpDelete attributes on an action method would result in either request type being allowed or no requests being allowed (since it can't be both a Post and a Delete at the same time). I noticed that ActionMethodSelectorAttribute, from which HttpPostAttribute and HttpDeleteAttribute both derive is decorated with [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)] I had expected it to not allow both HttpPost and HttpDelete on the same method because of this, but the compiler doesn't complain. My limited testing tells me that the attribute usage on the base class is simply ignored. AllowMultiple seemingly only disallows two of the same attribute from being applied to a method/class and doesn't seem to consider whether those attributes derive from the same class which is configured to not allow multiples. Moreover, the attribute usage on the base class doesn't even preclude your from changing the attribute usage on a derived class. That being the case, what's the point of even setting the values on the base attribute class? Is it just advisory or am I missing something fundamental in how they work? FYI - it turns out that using both basically precludes that method from ever being considered. The attributes are evaluated independently and one of them will always indicate that the method is not valid for the request since it can't simultaneously be both a Post and a Delete.

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• What's a good way to organize a large collection of personal scripts using git?

  - by spooky note

  I have a large collection of my personal scripts that I would like to start versioning using Git. I've previously organized my code as follows: ~/code/python/projects/ (for large stuff, each project contained in an individual folder) ~/code/python/scripts/ (single file scripts all contained in this directory) ~/code/python/sandbox/ (my testing area) ~/code/python/docs/ (downloaded documentation) ~/code/java/... (as above) Now i'm going to start versioning my code using git, so that I can have history and backup all my code to a remote server. I know if I were using SVN I would just keep my entire "~/code/" directory in a large repository, but I understand this is not a good way to do things with Git. Most info I've seen online suggests keeping all my project folders in a single place (as in, no separate directories for python or java) with each project containing it's own git repository, and simply having a "snippets" directory containing all single-file scripts/experiments that can be converted into projects at a later date. But I'm not sure how I feel about consolidating all of my code directories into one area. Is there a good way to keep my separate code directories intact, or is it not worth the effort? Maybe I'm just attached to the separate code directories because I've never known anything else... Also (as a side note), I'd like to quickly be able to see a chronological history of all my projects and scripts. So I can see which projects I created most recently. I used to do this by keeping a number at the beginning of all my projects, 002project, 003project. Is there automatic or easy way to do this in git without having to add a number to all of the project names? I'm open to any practical or philosophical code organizing advice you have. Thanks!!!

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• using same ids for many tags?

  - by gaurav rathor

  here is the example code that i was testing and i got confused that every one says that we can use or we should use only one time per id but i have testes using using it multiple times but its giving me the correct output. so what should i do. it is kinda working same like class for me in this example code: <html> <head> <style> #exampleID1 { background-color: blue; } #exampleID2 { text-transform: uppercase; } </style> </head> <body> <p id="exampleID1">This paragraph has an ID name of "exampleID1" and has a blue CSS defined background.</p> <p id="exampleID2">This paragraph has an ID name of "exampleID2" and has had its text transformed to uppercase letters.</p> <address id="exampleID1"> Written by W3Schools.com<br /> <a href="mailto:[email protected]">Email us</a><br /> Address: Box 564, Disneyland<br /> Phone: +12 34 56 78 </address> <blockquote id="exampleID1"> Here is a long quotation here is a long quotation here is a long quotation here is a long quotation here is a long quotation here is a long quotation here is a long quotation here is a long quotation here is a long quotation. </blockquote> </body> </html> please see the above code and answer me that why we should not use id selector two times in a page while its working fine.

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• What's the difference between UI development and front-end development?

  - by Nick Lowman

  I'm a front-end developer and really enjoy jQuery and JavaScript. I've built a lot a websites, done some good jQuery work and built a few JavaScript based applications and would really like to get in UI development. Or so I thought. I guessed it would be pretty similar to what I already do except maybe a little more JavaScript heavy but when I looked into it all the job specs said I needed to know about Scrum or Agile development, knowledge of testing frameworks and a good knowledge of JavaScript frameworks and custom events. So, from the specs I get the idea that a UI developer is actually a dedicated JavaScript developer. Is that the case? I understand (with much help from the users on stackoverflow), about JavaScript OO, inheritance, closures, custom events, debugging in Firefox or Aptana etc, and the people I work with seem to think I pretty OK at what I do but clearly my knowledge is not good enough to go for UI jobs. If anyone could tell me a little more about UI development and if there are any good resources for learning about it I would be most grateful as I couldn't find much on the internet.

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• Designing for varying mobile device resolutions, i.e. iPhone 4 & iPhone 3G

  - by Josh

  As the design community moves to design applications & interfaces for mobile devices, a new problem has arisen: Varying Screen DPI's. Here's the situation: Touch: * iPhone 3G/S ~ 160 dpi * iPhone 4 ~ 300 dpi * iPad ~ 126 dpi * Android device @ 480p ~ 200 dpi Point / click: * Laptop @ 720p ~ 96 dpi * Desktop @ 720p ~ 72 dpi There is certainly a clear distinction between desktop and mobile so having two separate front-ends to the same app is logical, especially when considering one is "touch"-based and the other is "point/click"-based. The challenge lies in designing static graphical elements that will scale between, say, 160 dpi and 300+ dpi, and get consistent and clean design across zoom levels. Any thoughts on how to approach this? Here are some scenarios, but each has drawbacks as well: * Design a single set of assets (high resolution), then adjust zoom levels based on detected resolution / device o Drawbacks: Performance caused by code layering, varying device support of Zoom * Develop & optimize multiple variations of image and CSS assets, then hide / show each based on device o Drawbacks: Extra work in design & QA. Anyone have thoughts or experience on how to deal with this? We should certainly be looking at methods that use / support HTML5 and CSS3.

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• Managing My Database in Source Control

  - by Jason

  As I am working with a new database project (within VS2008), and as I have never developed a database from scratch, I immediately began looking into how to manage a database within source control (in this case, Subversion). I found some information on SO, including this post: Keeping development databases in multiple environments in sync. One of the answers in particular pointed to a number of a links, all of which had good, useful information. I was reading a series of posts by K. Scott Allen which describe how he manages database change. From my reading (and please pardon the noobishness of my question), it seems as though the database itself is never checked into a repository. Rather, scripts that can build the database, along with test data (which is also populated from scripts) is checked into the repository. Ultimately, this means that, when a developer is testing his or her app, these scripts, which are part of the build process, are run. This ensures that the database is up-to-date, but is also run locally from every developer's machine. This makes sense to me (if I am indeed reading that correctly). However, if I am missing something, I would appreciate correction or additional guidance. In addition, another question I wanted to ask - does this also mean that I should NOT check in the mdf or ldf files that are created from Visual Studio? Thanks for any help and additional insight. Always appreciated.

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• Architecture of finding movable geotagged objects

  - by itsme

  I currently have a Postgres DB filled with approx. 300.000 data-sets of moving vehicles all over the world. My very frequently repeated query is: Give me all vehicles in a 5/10/20mile radius. Currently I spend around 600 to 1200 ms in the DB to prepare the set of located vehicle-objects. I am looking to vastly improve this time by ideally one or two orders of magnitude if possible. I am working in a Ruby on Rails 3.0beta environment if this is relevant. Any ideas how to architect the whole system to accelerate this query? Any NoSQL database able to deliver this kind of geolocation performance? I know of MongoDB working on an extension to facilitate this scenario but haven't tried it yet. Any intelligent use of Redis to achieve this? One problem with SQL-DBs here seems to be that I can't possibly use indexes because my vehicles are mostly moving around, meaning I had to constantly created DB indexes which, by itself, is probably more expensive than just doing the searching without index. Looking forward to your thoughs, Thanks!

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• Java: multi-threaded maps: how do the implementations compare?

  - by user346629

  I'm looking for a good hash map implementation. Specifically, one that's good for creating a large number of maps, most of them small. So memory is an issue. It should be thread-safe (though losing the odd put might be an OK compromise in return for better performance), and fast for both get and put. And I'd also like the moon on a stick, please, with a side-order of justice. The options I know are: HashMap. Disastrously un-thread safe. ConcurrentHashMap. My first choice, but this has a hefty memory footprint - about 2k per instance. Collections.sychronizedMap(HashMap). That's working OK for me, but I'm sure there must be faster alternatives. Trove or Colt - I think neither of these are thread-safe, but perhaps the code could be adapted to be thread safe. Any others? Any advice on what beats what when? Any really good new hash map algorithms that Java could use an implementation of? Thanks in advance for your input!

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• Receiving UDP on different Android phones gives different results

  - by user1868982

  I am willing to create a server and client program on my android mobile devices. The devices communicate with each other on the same wifi network, therefore, some simple scanning mechanism must be implemented - The client phones search for a server phone through some kind of broadcast. What I did: My protocol - the client phone broadcasts a message port p on the wifi, the server listens on port p. when the server gets the broadcast message it sends a message back, therefore discovering itself to the client. My code - I have opened a broadcast socket on my app, it sends a broadcast message. Meanwhile there is a python script on my PC that listens and replies - I use python so that my testing will be easier - Wireshark on the PC and I can see everything. What happens: When I use one of my Galaxy S phones - it works and I get a response. When I use the other Galaxy S phone - it doesn't work. Now this is what I know: The phone that works actually has Nexus ROM on it Ver. 4.1.1 The phone that doesn't work has 2.3.3 regular galaxy ROM The python code says it receives both of the broadcasts sent from both phones, and replies to both of them without raising any exception. So far I was thought the problem may be 1. the older version'd phone. 2. the windows firewall 3. the router firewall So I have opened Wireshark, and Indeed I saw that both phones are sending their broadcasts - it was logged on Wireshark. But the python script only responded to the first one. So this is why 1 & 3 are irrelevant - if the router firewall was blocking my UDP I would have still seen the python server response, same with the older versioned phone. To get rid of 2 i just disabled the windows firewall - still same problem. Does anyone has a clue to why this effect might happen? Thanks!

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• What's the right way to show a non-modal child dialog in MFC (VS2005)?

  - by John

  Rather than have everything in one big dialog, I'm looking at being able to display child dialogs for separate groups of controls. The idea is these are not free-floating child dialogs like floating toolbars, but would be shown with no title-bar, their position locked to the parent dialog... so as you drag the parent dialog any open child is dragged too. NOTE: these child windows are not inside the parent dialog, they would typically be 'glued' to the edge of it. In MFC/VC++ 2005, what's the best way to do this? For testing, I currently have a standard MFC Dialog-based app setup with CMainDlg, and I've then created a 'widget dialog' CWidgetDlg. So far I've got a member variable CWidgetDlg MainDlg::m_Widget and a button on CMainDlg with a handler like CMainDlg::OnDisplayWidgetBtn() { m_Widget.ShowWindow(TRUE); } But of course m_Widget hasn't got a HWND setup, and I am trying to remember the right way to do this? For dialog controls I can use DDX but what about child dialogs? And is this a reasonable approach, or is there a nicer, more automated way?

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