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  • Design patterns for Caching Images in a MVC?

    - by Onema
    Hi, I'm designing an image cache system that will be used in an MVC CMS. The main purpose of the image cacher is to modify images: scale, crop, etc and cache them in the client site. I have created an image cache Model and Mapper that interact with the Database, to keep track of the images and know what kind of actions have been applied to them (scale, crop, etc). In addition to the Model and Mapper I have created a ImageCacher Class that is used by the API to manage the Model and image creation based on arguments passed by the client site, this class creates the images and generates the links to the images for the View. A coworker argued that I need to include the functionality of this last Class inside the Model, as the bulk of the logic should go in the model. I respectfully disagree with him since I feel the model's responsibility is to deal with the information about the images cached at the database level, and the responsibility of the ImageCacher Class is to create the url/image that we will be caching (keeping the single responsibility principle). In addition to this I believe that a model should not have Presentation-related features, like creating or showing images. Does anyone have any insight on this? is there a particular design pattern that would make this division of tasks clear and and the image cacher reusable? Should I add all the logic in the Model? Thank you.

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  • New user register, script auto create problems!

    - by SKY
    Hi, im currently trying to create a php script that when a new user register, a script (eg:wordpress,blog etc..) will install for them. I'm currently got the code below for just single setup, but how can i setup a form for multi user? which only allowing them to input the username (subdomain) and password. <?php class scriptname_Config { public static $title = 'new_script_title'; // Domain name and path where new script will installed in public static $domain = 'username.domain.com'; public static $absolutePath = '/new_register_username/'; // Settings for general mysql database public static $db = array( 'host' => 'localhost', 'database' => 'scriptname', 'user' => 'root', 'password' => '', 'prefix' => 'scriptname_' ); } define( 'scriptname_BASE_URL', 'http://'.scriptname_Config::$domain.scriptname_Config::$absolutePath ); ?> Or any tutorial that will help is appreciate! Thanks!

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  • Why does my binding break down on SilverLight ProgressBars?

    - by Bill Jeeves
    I asked a similar question about charts but I have given up on that and I am using progress bars instead. Essentially, I have ten progress bars in a Silverlight control. Each is showing a different value and updating every couple of seconds (it's a process monitor). Each progress bar has the same minimum value and maximum value so the bars can be compared. Trying to follow the M-V-VM model, I have bound the value of each bar to a property in my ViewModel. All of the maximum values for the bar are bound to a single property. When the model updates, the values and the maximum can all update. This allows the bars to re-scale as the sizes grow. I'm finding that the binding will stop working sometimes on one or more bars. I suspect it is because a bar's value becomes higher than the maximum occasionally. This is because if I update the maximums first and they are going down, the values will be to high. If I update the values first when the maximum needs increasing, the values are too high again. Is there a way to stop this behaviour? Some way, perhaps, to tell the progress bars that it's OK to temporarily go too high? Or some way to tell the bindings that they shouldn't be disabled when this happens? Or maybe I've got this completely wrong and there's some other issue with ProgressBar binding I don't know about?

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  • HTML Table: How to resize data cells when already specified "colspan"?

    - by Jenny
    I have tabular data to display, which has a meaning to both rows and columns. Columns are time blocks, rows are days. A particular datacell is confined to a single day, but can be in multiple time block. To show this, I am using the colspan tag. <div id = "GuideTable"> <table> <tr> <td colspan = 3> </td></tr></table> </div> Or Whatever. I'm trying to apply CSS formating to the entire table, and for changing colors, etc, things are fine, but wanting to have a consistent width is where I am running into problems. Right now, each data cell's width seems tied to the maximum width in its column (everything auto lines up). Some columns are itty bitty, others are huge. I'm trying to make columns consistently sized (even if that means every column is as big as the biggest column needs to be), but setting an individual datacells width (either via css or in the tag itself) is getting me nowhere. I'm thinking maybe the colspan tag is overriding my manual width? If that's the case, how can I change the width of a column as a whole, especially since they aren't explicitly defined? (CAN you explicitly define columns?) Examples of the CSS I'm using: #GuideTable td{ background:#ffffff; border-style: solid; border-width: 1px; width: 100px; }

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  • FileSystemWatcher Work is Done?

    - by Snowy
    I setup a FsWatcher on a local filesystem directory. I only want to know when files are added to the directory so they can be moved to another filesystem. I seem to be able to detect when the first file is in, but actually I want to know when all files from a given copy operation are done. If I used Windows Explorer to copy files from one directory to another, Explorer would tell me that there are n seconds left in the transfer, so while there is some activity for the begin-transfer and end-transfer for each file, it appears that there is something for the begin-transfer and end-transfer for all files. I wonder if there is something similar that I can do just with the .NET Framework. I would like to know when "all" files are in and not just a single file in a "transaction". If there is nothing baked in, maybe I should come up with some kind of waiting/countering in order to only do my activity when a job is "done". Not sure if I'm making 100% sense on this one, please anyone comment. Thanks.

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  • Can anyone help me with this VHDL code (currently malfunctioning)?

    - by xx77aBs
    This code should be (and is) very simple, and I don't know what I am doing wrong. Here is description of what it should do: It should display a number on one 7-segment display. That number should be increased by one every time someone presses the push button. There is also reset button which sets the number to 0. That's it. Here is VHDL code: library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_ARITH.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity PWM is Port ( cp_in : in STD_LOGIC; inc : in STD_LOGIC; rst: in std_logic; AN : out STD_LOGIC_VECTOR (3 downto 0); segments : out STD_LOGIC_VECTOR (6 downto 0)); end PWM; architecture Behavioral of PWM is signal cp: std_logic; signal CurrentPWMState: integer range 0 to 10; signal inco: std_logic; signal temp: std_logic_vector (3 downto 0); begin --cp = 100 Hz counter: entity djelitelj generic map (CountTo => 250000) port map (cp_in, cp); debounce: entity debounce port map (inc, cp, inco); temp <= conv_std_logic_vector(CurrentPWMState, 4); ss: entity decoder7seg port map (temp, segments); process (inco, rst) begin if inco = '1' then CurrentPWMState <= CurrentPWMState + 1; elsif rst='1' then CurrentPWMState <= 0; end if; end process; AN <= "1110"; end Behavioral; Entity djelitelj (the counter used to divide 50MHz clock): library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_ARITH.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity PWM is Port ( cp_in : in STD_LOGIC; inc : in STD_LOGIC; rst: in std_logic; AN : out STD_LOGIC_VECTOR (3 downto 0); segments : out STD_LOGIC_VECTOR (6 downto 0)); end PWM; architecture Behavioral of PWM is signal cp: std_logic; signal CurrentPWMState: integer range 0 to 10; signal inco: std_logic; signal temp: std_logic_vector (3 downto 0); begin --cp = 100 Hz counter: entity djelitelj generic map (CountTo => 250000) port map (cp_in, cp); debounce: entity debounce port map (inc, cp, inco); temp <= conv_std_logic_vector(CurrentPWMState, 4); ss: entity decoder7seg port map (temp, segments); process (inco, rst) begin if inco = '1' then CurrentPWMState <= CurrentPWMState + 1; elsif rst='1' then CurrentPWMState <= 0; end if; end process; AN <= "1110"; end Behavioral; Debouncing entity: library IEEE; use IEEE.STD_LOGIC_1164.all; use IEEE.STD_LOGIC_ARITH.all; use IEEE.STD_LOGIC_UNSIGNED.all; ENTITY debounce IS PORT(pb, clock_100Hz : IN STD_LOGIC; pb_debounced : OUT STD_LOGIC); END debounce; ARCHITECTURE a OF debounce IS SIGNAL SHIFT_PB : STD_LOGIC_VECTOR(3 DOWNTO 0); BEGIN -- Debounce Button: Filters out mechanical switch bounce for around 40Ms. -- Debounce clock should be approximately 10ms process begin wait until (clock_100Hz'EVENT) AND (clock_100Hz = '1'); SHIFT_PB(2 Downto 0) <= SHIFT_PB(3 Downto 1); SHIFT_PB(3) <= NOT PB; If SHIFT_PB(3 Downto 0)="0000" THEN PB_DEBOUNCED <= '1'; ELSE PB_DEBOUNCED <= '0'; End if; end process; end a; And here is BCD to 7-segment decoder: library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_ARITH.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity decoder7seg is port ( bcd: in std_logic_vector (3 downto 0); segm: out std_logic_vector (6 downto 0)); end decoder7seg; architecture Behavioral of decoder7seg is begin with bcd select segm<= "0000001" when "0000", -- 0 "1001111" when "0001", -- 1 "0010010" when "0010", -- 2 "0000110" when "0011", -- 3 "1001100" when "0100", -- 4 "0100100" when "0101", -- 5 "0100000" when "0110", -- 6 "0001111" when "0111", -- 7 "0000000" when "1000", -- 8 "0000100" when "1001", -- 9 "1111110" when others; -- just - character end Behavioral; Does anyone see where I made my mistake(s) ? I've tried that design on Spartan-3 Started board and it isn't working ... Every time I press the push button, I get crazy (random) values. The reset button is working properly. Thanks !!!!

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  • How can I write a function template for all types with a particular type trait?

    - by TC
    Consider the following example: struct Scanner { template <typename T> T get(); }; template <> string Scanner::get() { return string("string"); } template <> int Scanner::get() { return 10; } int main() { Scanner scanner; string s = scanner.get<string>(); int i = scanner.get<int>(); } The Scanner class is used to extract tokens from some source. The above code works fine, but fails when I try to get other integral types like a char or an unsigned int. The code to read these types is exactly the same as the code to read an int. I could just duplicate the code for all other integral types I'd like to read, but I'd rather define one function template for all integral types. I've tried the following: struct Scanner { template <typename T> typename enable_if<boost::is_integral<T>, T>::type get(); }; Which works like a charm, but I am unsure how to get Scanner::get<string>() to function again. So, how can I write code so that I can do scanner.get<string>() and scanner.get<any integral type>() and have a single definition to read all integral types? Update: bonus question: What if I want to accept more than one range of classes based on some traits? For example: how should I approach this problem if I want to have three get functions that accept (i) integral types (ii) floating point types (iii) strings, respectively.

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  • Recover lost code from compiled apk

    - by AlexRamallo
    I have an issue here..and its making me really nervous. I was working on this game, and it was going great, so I took a copy of it on my laptop to work do some work while away from my computer. long story short, hard-drive failure + poor back ups led to me losing a very important class. Is there a way to decompile the apk to retrieve the bit of code that was lost? It isn't overly complicated or sophisticated, its just that its impossible to re-write it without reading every. single. line. of. code. in the entire application since it initializes a LOT of classes and loads a bunch of stuff in a specific way. With a quick google search I was able to find apktool, which decompiles it into a bunch of .smali files, which I don't think were designed for human reading. All I need to recover is one very big method in the class. I found the smali file that contains it and I think I found the line where it starts. something like .method public declared-synchronized load(Lcom/X/X/game/X;)I Anyone help would be appreciated since I would have to scrap the entire game without this method.

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  • Error 1009 after gotoAndStop - stage instance never gets added

    - by ELambda
    I've been through the forums for hours (days?) searching on 1009 errors, but I remain stumped on this. It seems very mysterious and I would LOVE some help if you have any ideas. I have a single .swf that is 7 frames long - each frame represents a different "page" and you can switch pages through a menu widget in the top right corner. The menu widget calls gotoAndPlay( "frame" ). Everything works fine except when I switch from one particular frame to another. Then, during initialization of the new frame (setting some visible properties on various items, in actionscript), I get the dreaded 1009 error on a specific stage instance, a dynamic text instance i_word. Here's what I've tried so far: made sure the actionscript for the new frame starts with a stop() statement before starting initialization - no dice tried changing i_word into a movie_clip instead of dynamic text, made sure it was exported for actionscript - no difference. (I also have 2 other dynamic text instances on the same page that don't seem to cause a problem) added an ENTER_FRAME listener when the new frame is loaded, in case the problem was a timing issue. Put in a big if statement checking if i_word and other instances are not null before proceeding to initialization. It never enters the if, because i_word NEVER gets added. I added trace statements for all instances that are null, and it is the only one. If I remove all references to i_word in my actionscript, everything else is not null, and things go forward. The text for i_word even shows up on the screen in that case. tried renaming i_word - no dice tried deleting the layer i_word was on and adding a new layer - no dice It feels like there is a serious Gremlin in my flash file somewhere. Or maybe I'm missing something obvious. Let me know if you have any ideas...I'd be so grateful. Thank you! Elambda

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  • Java: Inputting text from a file using split

    - by 00PS
    I am inputting an adjacency list for a graph. There are three columns of data (vertex, destination, edge) separated by a single space. Here is my implementation so far: FileStream in = new FileStream("input1.txt"); Scanner s = new Scanner(in); String buffer; String [] line = null; while (s.hasNext()) { buffer = s.nextLine(); line = buffer.split("\\s+"); g.add(line[0]); System.out.println("Added vertex " + line[0] + "."); g.addEdge(line[0], line[1], Integer.parseInt(line[2])); System.out.println("Added edge from " + line[0] + " to " + line[1] + " with a weight of " + Integer.parseInt(line[2]) + "."); } System.out.println("Size of graph = " + g.size()); Here is the output: Added vertex a. Added edge from a to b with a weight of 9. Exception in thread "main" java.lang.NullPointerException at structure5.GraphListDirected.addEdge(GraphListDirected.java:93) at Driver.main(Driver.java:28) I was under the impression that line = buffer.split("\\s+"); would return a 2 dimensional array of Strings to the variable line. It seemed to work the first time but not the second. Any thoughts? I would also like some feedback on my implementation of this problem. Is there a better way? Anything to help out a novice! :)

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  • Running an application from an USB device...

    - by Workshop Alex
    I'm working on a proof-of-concept application, containing a WCF service with console host and client, both on a single USB device. On the same device I will also have the client application which will connect to this service. The service uses the entity framework to connect to the database, which in this POC will just return a list of names. If it works, it will be used for a larger project. Creating the client and service was easy and this works well from USB. But getting the service to connect to the database isn't. I've found this site, suggesting that I should modify machine.config but that stops the XCopy deployment. This project cannot change any setting of the PC, so this suggestion is bad. I cannot create a deployment setup either. The whole thing just needs to run from USB disk. So, how do I get it to run? (The service just selects a list of names from the database, which it returns to the client. If this POC works, it will do far more complex things!)

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  • Porting Perl to C++ `print "\x{2501}" x 12;`

    - by jippie
    I am porting a program from Perl to C++ as a learning objective. I arrived at a routine that draws a table with commands like the following: Perl: print "\x{2501}" x 12; And it draws 12 times a '?' ("box drawings heavy horizontal"). Now I figured out part of the problem already: Perl: \x{}, \x00 Hexadecimal escape sequence; C++: \unnnn To print a single Unicode character: C++: printf( "\u250f\n" ); But does C++ have a smart equivalent for the 'x' operator or would it come down to a for loop? UPDATE Let me include the full source code I am trying to compile with the proposed solution. The compiler does throw an errors: g++ -Wall -Werror project.cpp -o project project.cpp: In function ‘int main(int, char**)’: project.cpp:38:3: error: ‘string’ is not a member of ‘std’ project.cpp:38:15: error: expected ‘;’ before ‘s’ project.cpp:39:3: error: ‘cout’ is not a member of ‘std’ project.cpp:39:16: error: ‘s’ was not declared in this scope #include <stdlib.h> #include <stdint.h> #include <stdio.h> #include <string.h> int main ( int argc, char *argv[] ) { if ( argc != 2 ) { fprintf( stderr , "usage: %s matrix\n", argv[0] ); exit( 2 ); } else { //std::string s(12, "\u250f" ); std::string s(12, "u" ); std::cout << s; } }

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  • Parallelize or vectorize all-against-all operation on a large number of matrices?

    - by reve_etrange
    I have approximately 5,000 matrices with the same number of rows and varying numbers of columns (20 x ~200). Each of these matrices must be compared against every other in a dynamic programming algorithm. In this question, I asked how to perform the comparison quickly and was given an excellent answer involving a 2D convolution. Serially, iteratively applying that method, like so list = who('data_matrix_prefix*') H = cell(numel(list),numel(list)); for i=1:numel(list) for j=1:numel(list) if i ~= j eval([ 'H{i,j} = compare(' char(list(i)) ',' char(list(j)) ');']); end end end is fast for small subsets of the data (e.g. for 9 matrices, 9*9 - 9 = 72 calls are made in ~1 s). However, operating on all the data requires almost 25 million calls. I have also tried using deal() to make a cell array composed entirely of the next element in data, so I could use cellfun() in a single loop: # who(), load() and struct2cell() calls place k data matrices in a 1D cell array called data. nextData = cell(k,1); for i=1:k [nextData{:}] = deal(data{i}); H{:,i} = cellfun(@compare,data,nextData,'UniformOutput',false); end Unfortunately, this is not really any faster, because all the time is in compare(). Both of these code examples seem ill-suited for parallelization. I'm having trouble figuring out how to make my variables sliced. compare() is totally vectorized; it uses matrix multiplication and conv2() exclusively (I am under the impression that all of these operations, including the cellfun(), should be multithreaded in MATLAB?). Does anyone see a (explicitly) parallelized solution or better vectorization of the problem?

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  • Tips for using Subversion and XCode in a team project

    - by FelipeUY
    Hi to all. I've been working on an Xcode (iPhone) project with three different persons. We have the project on a Subversion repository, but we still don't completely understand some aspects of the Subversion + Xcode methodology: 1) Each time someone does a commit on a single file, it may appear or not in the project of the other developers. Even though the same person that creates the new files, it adds those files to the Repository and then it commits on those files. Why does that happens? Any suggestions? 2) Each person that is involved on the project can't do a "Commit entire project" without causing a considerable headache to the rest of the developers... any idea how this should be done?. The working methodology that we are trying to implement is that only one developer (generally the leader of the project) can Commit the entire project but he must inform the rest of the team, so everybody can be prepared to receive a message asking him to discard his changes and read the new files from the repository. I need suggestions or advice on how to handle a project with multiple developers using subversion. We have read the Subversion handbook, and many other messages on StackOverflow but I still can't find any useful advice. Thanks for any tip!

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  • How do I do a table join on two fields in my second table?

    - by Cannonade
    I have two tables: Messages - Amongst other things, has a to_id and a from_id field. People - Has a corresponding person_id I am trying to figure out how to do the following in a single linq query: Give me all messages that have been sent to and from person x (idself). I had a couple of cracks at this. Not quite right MsgPeople = (from p in db.people join m in db.messages on p.person_id equals m.from_id where (m.from_id == idself || m.to_id == idself) orderby p.name descending select p).Distinct(); This almost works, except I think it misses one case: "people who have never received a message, just sent one to me" How this works in my head So what I really need is something like: join m in db.messages on (p.people_id equals m.from_id or p.people_id equals m.to_id) Gets me a subset of the people I am after It seems you can't do that. I have tried a few other options, like doing two joins: MsgPeople = (from p in db.people join m in AllMessages on p.person_id equals m.from_id join m2 in AllMessages on p.person_id equals m2.to_id where (m2.from_id == idself || m.to_id == idself) orderby p.name descending select p).Distinct(); but this gives me a subset of the results I need, I guess something to do with the order the joins are resolved. My understanding of LINQ (and perhaps even database theory) is embarrassingly superficial and I look forward to having some light shed on my problem.

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  • Python/Sqlite app for web or desktop?

    - by ChrisC
    I am in the planning stages of rewriting an Access db I wrote several years ago in a full fledged program. I have very slight experience coding, but not enough to call myself a programmer by far. I'll definitely be learning as I go, so I'd like to keep everything as simple as possible. I've decided on Python and SQLite for my program, but I need help on my next decision. Here is my situation 1) It'll be a desktop program, run locally on each machine, all Windows 2) I want a nice looking GUI with colors, different shaped buttons, nice menus, lists, etc, etc 3) I'm thinking about using a browser interface because (a) from what I've read, browser apps can look really great, and (b) I understand there are lots of free tools to assist in setting up the GUI/GUI code with drag and drop tools, so that helps my "keep it simple" goal. 4) I want the program to be totally portable so it runs completely from one single folder on a user's PC. If I do go the browser app router, a major concern I have is the possibility that a user's browser settings could affect or break the app. How likely is this? What other pros and cons are there for my situation?

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  • How to strip out 0x0a special char from utf8 file using c# and keep file as utf8?

    - by user1013388
    The following is a line from a UTF-8 file from which I am trying to remove the special char (0X0A), which shows up as a black diamond with a question mark below: 2464577 ????? True s6620178 Unspecified <1?1009-672 This is generated when SSIS reads a SQL table then writes out, using a flat file mgr set to code page 65001. When I open the file up in Notepad++, displays as 0X0A. I'm looking for some C# code to definitely strip that char out and replace it with either nothing or a blank space. Here's what I have tried: string fileLocation = "c:\\MyFile.txt"; var content = string.Empty; using (StreamReader reader = new System.IO.StreamReader(fileLocation)) { content = reader.ReadToEnd(); reader.Close(); } content = content.Replace('\u00A0', ' '); //also tried: content.Replace((char)0X0A, ' '); //also tried: content.Replace((char)0X0A, ''); //also tried: content.Replace((char)0X0A, (char)'\0'); Encoding encoding = Encoding.UTF8; using (FileStream stream = new FileStream(fileLocation, FileMode.Create)) { using (BinaryWriter writer = new BinaryWriter(stream, encoding)) { writer.Write(encoding.GetPreamble()); //This is for writing the BOM writer.Write(content); } } I also tried this code to get the actual string value: byte[] bytes = { 0x0A }; string text = Encoding.UTF8.GetString(bytes); And it comes back as "\n". So in the code above I also tried replacing "\n" with " ", both in double quotes and single quotes, but still no change. At this point I'm out of ideas. Anyone got any advice? Thanks.

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  • In maven2, how do I assemble bits and pieces of different modules to create final distributions?

    - by Carcassi
    I have four maven project: client api jar web service war ui jar web interface war The service war will need to be packaged to include the client api jar, together with javadocs (so that each version is distributed with a matching client and documentation). The web interface war will need the ui jar and all the dependencies (webstart/applet deployment). So I need a 5th project that does all the packaging. How to do this with ant or a script is perfectly clear to me, but not in maven. I tried the following: having the javadocs included as part of the war packaging: this requires the execution of the javadocs goal in project 1 before execution of package in project 2. Haven't found a way to bind plugins/goals across different projects. Using the assembly plugin in project2 had the same problem. create a fifth project and use the assembly plugin. Still the same problems as before, with the problem that since I need different pieces from each sub-project I do not understand how this can be done using the assembly. Is this too hard to do in maven, and should I just give up? Or I am looking at it wrong, in which case, how should I be looking at it? Thanks! Upon further reflection, here is a partial answer: Each project should build all its artifacts. This is done by having the plugins configured to run as per the prepare-resources and package phases. So, in my case, I prepare all that needs to be generated (jar, javadocs, xsd documentation, ...) as different artifacts so that a single "package" goal execution creates all. So, it's not "how project 2 forces project 1 to run different goals", but it's "make project 1 create all of its artifact as part as the normal lifecycle). This seems to simplify things.

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  • Methods to see result fo a code change faster

    - by Can't Tell
    This question came to me when developing using Eclipse. I use JBoss Application Server and use hot code replacement. But this option requires that the 'build automatically' option to be enabled. This makes Eclipse build the workspace automatically (periodically or when a file is saved?) and for a large code base this takes too much time and processing which makes the machine freeze for a while. Also sometimes an error message is shown saying that hot code replacement failed. The question that I have is: is there a better way to see the result of a code change? Currently I have the following two suggestions: Have unit tests - this will allow to run a single test and see the result of a code change. ( But for a JavaEE application that uses EJBs is it easy to setup unit tests?) Use OSGi - which allows to add jars to the running system without bringing down the JVM. Any ideas on above suggestions or any other suggestion or a framework that allows to do this is welcome.

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  • How string accepting interface should look like?

    - by ybungalobill
    Hello, This is a follow up of this question. Suppose I write a C++ interface that accepts or returns a const string. I can use a const char* zero-terminated string: void f(const char* str); // (1) The other way would be to use an std::string: void f(const string& str); // (2) It's also possible to write an overload and accept both: void f(const char* str); // (3) void f(const string& str); Or even a template in conjunction with boost string algorithms: template<class Range> void f(const Range& str); // (4) My thoughts are: (1) is not C++ish and may be less efficient when subsequent operations may need to know the string length. (2) is bad because now f("long very long C string"); invokes a construction of std::string which involves a heap allocation. If f uses that string just to pass it to some low-level interface that expects a C-string (like fopen) then it is just a waste of resources. (3) causes code duplication. Although one f can call the other depending on what is the most efficient implementation. However we can't overload based on return type, like in case of std::exception::what() that returns a const char*. (4) doesn't work with separate compilation and may cause even larger code bloat. Choosing between (1) and (2) based on what's needed by the implementation is, well, leaking an implementation detail to the interface. The question is: what is the preffered way? Is there any single guideline I can follow? What's your experience?

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  • WCF operationcontract with List type unavailable in (Silverlight) client

    - by Dave
    This is the first time I have tried returning a List of data to a Silverlight client, so I'm having trouble getting the client to recognize this operationcontract. All others are fine. I have a method on the server called ReadOwFileData that needs to return a List. ReadOwFileDataCompletedEventArgs shows up in the Object Browser in the client, but not ReadOwFileDataAsync. What I want is similar to the tutorial here. The Dictionary collection type on the client is set to System.Collections.Generic.List. I tried deleting and recreating the service reference. Web.Config on the server is using basicHttpBinding. Here is the operationcontract on the server: [OperationContract] public List<OwFileData> ReadOwFileData(string OrderID) { DataClasses1DataContext db = new DataClasses1DataContext(); var dFileData = (from p in db.OwFileDatas where p.OrderID == OrderID select p).ToList(); List<OwFileData> x = new List<OwFileData>(dFileData); return x; } Incidently, this works fine: [OperationContract] public Customer GetShippingAndContactInfo(string login, string ordernum) { DataClasses1DataContext db = new DataClasses1DataContext(); Customer dInfo = (from p in db.Customers where p.Login == login select p).Single(); return dInfo; } I would like to read this data in the client and place it into an object I created called ObservableCollection. But that obviously can't happen until the client can see the method on the server. I do not know if this is an acceptable start, but this is what is on the client so far. The ReadOwFileDataAsync object is null: void populatefilesReceivedDataSource(string OrderID) { ArtUpload.ServiceReference1.UploadServiceClient client = new ArtUpload.ServiceReference1.UploadServiceClient(); var myList = client.ReadOwFileDataAsync(OrderID); // can I just itterate thru the list instead of 'binding' }

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  • How can I add two models in one form, where one model is a has_many :through?

    - by Angela
    How do I model having multiple Addresses for a Company and assign a single Address to a Contact? Contacts belong_to a Company. A Company has_many Contacts. A Company also has_many Addresses. And each Contact has_one Address. I want to be able, whenever I create a New Contact, to access all the addresses in all Contacts that belong to the Company. Here is are my Models: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address belongs_to :company has_one :address accepts_nested_attributes_for :address end class Address < ActiveRecord::Base attr_accessible :street1 has_many :contacts end How do I create the View in the _form for Contacts so that I can 1) Add an Address when creating a Contact; 2) Display the options of the Address. Here is how I am doing step 1, which is just to add a new address for a new contact: <% f.fields_for :addresses do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> Right now, what I have doesn't work. The console says I cannot mass-assign addresses when I hit "submit" on this New contact form.

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  • How do I make a lock that allows only ONE thread to read from the resource ?

    - by mare
    I have a file that holds an integer ID value. Currently reading the file is protected with ReaderWriterLockSlim as such: public int GetId() { _fileLock.EnterUpgradeableReadLock(); int id = 0; try { if(!File.Exists(_filePath)) CreateIdentityFile(); FileStream readStream = new FileStream(_filePath, FileMode.Open, FileAccess.Read); StreamReader sr = new StreamReader(readStream); string line = sr.ReadLine(); sr.Close(); readStream.Close(); id = int.Parse(line); return int.Parse(line); } finally { SaveNextId(id); // increment the id _fileLock.ExitUpgradeableReadLock(); } } The problem is that subsequent actions after GetId() might fail. As you can see the GetId() method increments the ID every single time, disregarding what happens after it has issued an ID. The issued ID might be left hanging (as said, exceptions might occur). As the ID is incremented, some IDs might be left unused. So I was thinking of moving the SaveNextId(id) out, remove it (the SaveNextId() actually uses the lock too, except that it's EnterWriteLock). And call it manually from outside after all the required methods have executed. That brings out another problem - multiple threads might enter the GetId() method before the SaveNextId() gets executed and they might all receive the same ID. I don't want any solutions where I have to alter the IDs after the operation, correcting them in any way because that's not nice and might lead to more problems. I need a solution where I can somehow callback into the FileIdentityManager (that's the class that handles these IDs) and let the manager know that it can perform the saving of the next ID and then release the read lock on the file containing the ID. Essentialy I want to replicate the relational databases autoincrement behaviour - if anything goes wrong during row insertion, the ID is not used, it is still available for use but it also never happens that the same ID is issued. Hopefully the question is understandable enough for you to provide some solutions..

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  • Git repositories on shared hosting with ssh access - multiple users / one ssh account

    - by acp
    I'm part of a small team trying to start coding on a project. I've decided it's time to give git a chance (no more svn) and was trying to see if we could use our shared web hosting to deploy a "public" repository there so that we can easily push/pull to/from it and keep up-to-date with each others changes. The problem I'm having now is that we only have a single ssh account for that hosting. Having used svn in the past, I could enforce a svn username on a given pair of ssh keys, however I don't seem to be able to do something similar with git (in other words tie the ssh keypair to a specific dev). I don't mind everybody having read/write permissions everywhere, since anything that is private should stay on each others machine. Finally, solutions such as gitosis can not be used. I guess my question to you is how is accountability to git pushes given? Is it tied to the ssh account being used, or the email address given in git config? Can I create different ssh keys for every developer (for the same ssh account though), and just send them to the devs?

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  • Should core application configuration be stored in the database, and if so what should be done to se

    - by Rl
    I'm writing an application around a lot of hierarchical data. Currently the hierarchy is fixed, but it's likely that new items will be added to the hierarchy in the future. (please let them be leaves) My current application and database design is fairly generic and nothing dealing with specific nodes in the hierarchy is hardcoded, with the exception of validation and lookup functions written to retrieve external data from each node's particular database. This pleases me from a design point of view, but I'm nervous at the realization that the entire application rests on a handful of records in the database. I'm also frustrated that I have to enforce certain aspects of data integrity with database triggers rather than by foreign key constraints (an example is where several different nodes in the hierarchy have their own proprietary IDs and I store them in a single column which, when coupled with the node ID can be used to locate the foreign data). I'm starting to wonder whether it may have been appropriate to simply hardcoded these known nodes into the system so that it would be more "type safe" and less generic. How does one know when something should be hardcoded, and when it should be a configuration item? Is it just a cost-benefit analysis of clarity/safety now vs less work later, or am I missing some metric I should be using to determine whether or not this is appropriate. The steps I'm taking to protect these valuable configurations are to add triggers that prevent updates/deletes. The database user that this application uses will only have the ability to manipulate data through stored procedures. What else can I do?

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