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  • Combobox having values but not showing text

    - by ras
    hi, I'm using GWT-EXT combobox. My problem is when I render the combobox, it's having as many rows as it has values but all the rows are empty means text is not shown. Here's my code. Combobox cb = new Combobox(); cb.setForceSelection(true); cb.setMinChars(1); cb.setWidth(200); cb.setStore(store); // Store is perfectly loaded in combobox cb.setDisplayField("ReportName"); cb.setMode(ComboBox.LOCAL); cb.setTriggerAction(ALL); cb.setEmptyText("--Select--"); cb.setLoadingText("Searching..."); cb.setTypeAhead(true); cb.setSelectOnFocus(true); All other code is working fine. I'm sure for one thing that this problem is related to one of the functions of Combobox. Thanks in advance.

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  • How to implement a 'safe' periodical executer without using the Rails helpers?

    - by Robbie
    I am very new to Ruby on Rails and was never really big on writing JavaScript, so the built in helpers were like a tiny silce of heaven. However I have recently learned that using the helper methods creates "obtrusive javascript" so I am doing a tiny bit of refactoring to get all this messy code out of my view. I'm also using the Prototype API to figure out what all these functions do. Right now, I have: <%= periodically_call_remote(:url => {:action => "tablerefresh", :id => 1 }, :frequency => '5', :complete => "load('26', 'table1', request.responseText)")%> Which produces: <script type="text/javascript"> //<![CDATA[ new PeriodicalExecuter(function() {new Ajax.Request('/qrpsdrail/grids/tablerefresh/1', {asynchronous:true, evalScripts:true, onComplete:function(request){load('26', 'table1', request.responseText)}, parameters:'authenticity_token=' + encodeURIComponent('dfG7wWyVYEpelfdZvBWk7MlhzZoK7VvtT/HDi3w7gPM=')})}, 5) //]]> </script> My concern is that the "encodeURIComponent" and the presence of "authenticity_token" are generated by Rails. I'm assuming these are used to assure the validity of a request. (Ensuring a request comes from a currently active session?) If that is the case, how can I implement this in application.js 'safely'? It seems that the built in method, although obtrusive, does add some beneficial security. Thanks, in advance, to all who answer.

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  • Understanding how software testing works and what to test.

    - by RHaguiuda
    Intro: I've seen lots of topics here on SO about software testing and other terms I don't understand. Problem: As a beginner developer I, unfortunately, have no idea how software testing works, not even how to test a simple function. This is a shame, but thats the truth. I also hope this question can help others beginners developers too. Question: Can you help me to understand this subject a little bit more? Maybe some questions to start would help: When I develop a function, how should I test it? For example: when working with a sum function, should I test every input value possible or just some limits? How about testing functions with strings as parameters? In a big program, do I have to test every single piece of code of it? When you guys program do you test every code written? How automated test works and how can I try one? How tools for automated testing works and what they do? I`ve heard about unit testing. Can I have a brief explanation on this? What is a testing framework? If possible please post some code with examples to clarify the ideas. Any help on this topic is very welcome! Thanks.

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  • How to report progress of a JavaScript function?

    - by LambyPie
    I have a JavaScript function which is quite long and performs a number of tasks, I would like to report progress to the user by updating the contents of a SPAN element with a message as I go. I tried adding document.getElementById('spnProgress').innerText = ... statements throughout the function code. However, whilst the function is executing the UI will not update and so you only ever see the last message written to the SPAN which is not very helpful. My current solution is to break the task up into a number of functions, at the end of each I set the SPAN message and then "trigger" the next one with a window.setTimeout call with a very short delay (say 10ms). This yields control and allows the browser to repaint the SPAN with the updated message before starting the next step. However I find this very messy and difficult to follow the code, I'm thinking there must be a better way. Does anyone have any suggestions? Is there any way to force the SPAN to repaint without having to leave the context of the function? Thanks

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  • Visual Studio and .NET programming

    - by Vit
    Hi, I just want to ask wheather I am right or not about .NET. So, .NET is new framework that enables you to easily implement new and old windows functions. It is similiar to java in the way that its also compiled into "bytecode", but its name is Common Language Infrastructure, or CLI. This language is interpreted by .NET Framework, so code generated by programming using .NET cannot be executed directly by CPU. Now, few languages can be compiled to CLI. First, it was Microsoft-developed C#, than J#, C++ others. I suspect that this is in general right, at least I hope I understand it right. But, what I am still missing is, can you write to machine code compiled code in C#? And, if using Visual Studio 2005, when I select Win32 project, it is compiled into machine code, so only thing you need to run this apps are windows dynamic-link libraries, since static libraries code is implemented into app durink linking phase. And those dynamic-link libraries are implemented in every windows installation, or provided by DirectX installations. But when I select CLR in Visual Studio 2005, than app is compiled into CLI code, and it first executes .NET framework, and than .NET framework executes that program, since its not in machine code. So, I am right? I ask becouse you can read these infos on the internet, but I have noone to tell me wheather I understand it right or not. Thanks.

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  • Elegantly determine if more than one boolean is "true"

    - by Ola Tuvesson
    I have a set of five boolean values. If more than one of these are true I want to excecute a particular function. What is the most elegant way you can think of that would allow me to check this condition in a single if() statement? Target language is C# but I'm interested in solutions in other languages as well (as long as we're not talking about specific built-in functions). One interesting option is to store the booleans in a byte, do a right shift and compare with the original byte. Something like if(myByte && (myByte 1)) But this would require converting the separate booleans to a byte (via a bitArray?) and that seems a bit (pun intended) clumsy... [edit]Sorry, that should have been if(myByte & (myByte - 1)) [/edit] Note: This is of course very close to the classical "population count", "sideways addition" or "Hamming weight" programming problem - but not quite the same. I don't need to know how many of the bits are set, only if it is more than one. My hope is that there is a much simpler way to accomplish this.

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  • HTTP Negotiate windows vs. Unix server implementation using python-kerberos

    - by ondra
    I tried to implement a simple single-sign-on in my python web server. I have used the python-kerberos package which works nicely. I have tested it from my Linux box (authenticating against active directory) and it was without problem. However, when I tried to authenticate using Firefox from Windows machine (no special setup, just having the user logged into the domain + added my server into negotiate-auth.trusted-uris), it doesn't work. I have looked at what is sent and it doesn't even resemble the things the Linux machine sends. This Microsoft description of the process pretty much resembles the way my interaction from Linux works, but the Windows machine generally sends a very short string, which doesn't even resemble the things microsoft documentation states, and when base64 decoded, it is something like 12 zero bytes followed by 3 or 4 non-zero bytes (GSS functions then return that it doesn't support such scheme) Either there is something wrong with the client Firefox settings, or there is some protocol which I am supposed to follow for the Negotiate protocol, but which I cannot find any reference anywhere. Any ideas what's wrong? Do you have any idea what protocol I should by trying to find, as it doesn' look like SPNEGO, at least from MS documentation.

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  • How can I remove relative path components but leave symlinks alone in Perl?

    - by jnylen
    I need to get Perl to remove relative path components from a Linux path. I've found a couple of functions that almost do what I want, but: File::Spec->rel2abs does too little. It does not resolve ".." into a directory properly. Cwd::realpath does too much. It resolves all symbolic links in the path, which I do not want. Perhaps the best way to illustrate how I want this function to behave is to post a bash log where FixPath is a hypothetical command that gives the desired output: '/tmp/test'$ mkdir -p a/b/c1 a/b/c2 '/tmp/test'$ cd a '/tmp/test/a'$ ln -s b link '/tmp/test/a'$ ls b link '/tmp/test/a'$ cd b '/tmp/test/a/b'$ ls c1 c2 '/tmp/test/a/b'$ FixPath . # rel2abs works here ===> /tmp/test/a/b '/tmp/test/a/b'$ FixPath .. # realpath works here ===> /tmp/test/a '/tmp/test/a/b'$ FixPath c1 # rel2abs works here ===> /tmp/test/a/b/c1 '/tmp/test/a/b'$ FixPath ../b # realpath works here ===> /tmp/test/a/b '/tmp/test/a/b'$ FixPath ../link/c1 # neither one works here ===> /tmp/test/a/link/c1 '/tmp/test/a/b'$ FixPath missing # should work for nonexistent files ===> /tmp/test/a/b/missing

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  • Exporting de-aggregated data

    - by Ben
    I'm currently working on a data export feature for a survey application. We are using SQL2k8. We store data in a normalized format: QuestionId, RespondentId, Answer. We have a couple other tables that define what the question text is for the QuestionId and demographics for the RespondentId... Currently I'm using some dynamic SQL to generate a pivot that joins the question table to the answer table and creates an export, its working... The problem is that it seems slow and we don't have that much data (less than 50k respondents). Right now I'm thinking "why am I 'paying' to de-aggregate the data for each query? Why don't I cache that?" The data being exported is based on dynamic criteria. It could be "give me respondents that completed on x date (or range)" or "people that like blue", etc. Because of that, I think I have to cache at the respondent level, find out what respondents are being exported and then select their combined cached de-aggregated data. To me the quick and dirty fix is a totally flat table, RespondentId, Question1, Question2, etc. The problem is, we have multiple clients and that doesn't scale AND I don't want to have to maintain the flattened table as the survey changes. So I'm thinking about putting an XML column on the respondent table and caching the results of a SELECT * FROM Data FOR XML AUTO WHERE RespondentId = x. With that in place, I would then be able to get my export with filtering and XML calls into the XML column. What are you doing to export aggregated data in a flattened format (CSV, Excel, etc)? Does this approach seem ok? I worry about the cost of XML functions on larger result sets (think SELECT RespondentId, XmlCol.value('//data/question_1', 'nvarchar(50)') AS [Why is there air?], XmlCol.RinseAndRepeat)... Is there a better technology/approach for this? Thanks!

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  • Should my validator have access to my entire model?

    - by wb
    As the title states I'm wondering if it's a good idea for my validation class to have access to all properties from my model. Ideally, I would like to do that because some fields require 10+ other fields to verify whether it is valid or not. I could but would rather not have functions with 10+ parameters. Or would that make the model and validator too coupled with one another? Here is a little example of what I mean. This code however does not work because it give an infinite loop! Class User Private m_UserID Private m_Validator Public Sub Class_Initialize() End Sub Public Property Let Validator(value) Set m_Validator = value m_Validator.Initialize(Me) End Property Public Property Get Validator() Validator = m_Validator End Property Public Property Let UserID(value) m_UserID = value End property Public Property Get UserID() UserID = m_Validator.IsUserIDValid() End property End Class Class Validator Private m_User Public Sub Class_Initialize() End Sub Public Sub Initialize(value) Set m_User = value End Sub Public Function IsUserIDValid() IsUserIDValid = m_User.UserID > 13 End Function End Class Dim mike : Set mike = New User mike.UserID = 123456 mike.Validator = New Validator Response.Write mike.UserID If I'm right and it is a good idea, how can I go a head and fix the infinite loop with the get property UserID? Thank you.

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  • SWIG interface to receive an opaque struct reference in Java through function argument

    - by Beeo
    I am trying to use SWIG in order to use the Spotify API (libspotify) for Android: https://developer.spotify.com/technologies/libspotify/ I am having trouble defining the SWIG interface file to be able to successfully call the following native C function: sp_error sp_session_create(const sp_session_config * config, sp_session ** sess); Which in C would be called like this: //config struct defined previously sp_session *sess; sp_session_create(&config, &sess); But in Java I would need to call it like this: //config object defined previously sp_session javaSess = new sp_session(); sp_session_create(config, javaSess); sp_session is an opaque struct and is only defined in libspotify's API.h file as: typedef struct sp_session sp_session; I'm expecting the libspotify library to create it and give me a reference to it. The only thing I need that reference for then is to pass to other functions in the API. I believe the answer lies within the SWIG interface and typemaps, but I have been unsuccessful in trying to apply the examples I found in the documentation: http://www.swig.org/Doc2.0/SWIGDocumentation.html#Java_struct_pointer_pointer `http://www.swig.org/Doc2.0/SWIGDocumentation.html#Java_using_typemaps_return_arguments Help!

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  • question about jQuery droppable/draggable.

    - by FALCONSEYE
    I modified a sample photo manager application. photo manager application Instead of photos, I have employee records coming from a query. My version will let managers mark employees as on vacation, or at work. One of the things I did is to include employee ids like <a href="123">. I get the ids from event.target. This works for the click function but not for the "droppable" function. This is what I have for the click function: $('ul.gallery > li').click(function(ev) { var $item = $(this); var $unid = ev.target; var $target = $(ev.target); if ($target.is('a.ui-icon-suitcase')) { deleteImage($item,$unid); } else if ($target.is('a.ui-icon-arrowreturnthick-1-w')) { recycleImage($item,$unid); } return false; }); ev.target correctly gives the employee id. when i try the same in one of the droppable functions: $gallery.droppable({ accept: '#suitcase li', activeClass: 'custom-state-active', drop: function(ev, ui) { var $unid = ev.target; alert($unid); recycleImage(ui.draggable,$unid); } }); the alert(ui) gives me [object]. What's in this object? How do i get the href out of this? thanks

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  • TicTacToe strategic reduction

    - by NickLarsen
    I decided to write a small program that solves TicTacToe in order to try out the effect of some pruning techniques on a trivial game. The full game tree using minimax to solve it only ends up with 549,946 possible games. With alpha-beta pruning, the number of states required to evaluate was reduced to 18,297. Then I applied a transposition table that brings the number down to 2,592. Now I want to see how low that number can go. The next enhancement I want to apply is a strategic reduction. The basic idea is to combine states that have equivalent strategic value. For instance, on the first move, if X plays first, there is nothing strategically different (assuming your opponent plays optimally) about choosing one corner instead of another. In the same situation, the same is true of the center of the walls of the board, and the center is also significant. By reducing to significant states only, you end up with only 3 states for evaluation on the first move instead of 9. This technique should be very useful since it prunes states near the top of the game tree. This idea came from the GameShrink method created by a group at CMU, only I am trying to avoid writing the general form, and just doing what is needed to apply the technique to TicTacToe. In order to achieve this, I modified my hash function (for the transposition table) to enumerate all strategically equivalent positions (using rotation and flipping functions), and to only return the lowest of the values for each board. Unfortunately now my program thinks X can force a win in 5 moves from an empty board when going first. After a long debugging session, it became apparent to me the program was always returning the move for the lowest strategically significant move (I store the last move in the transposition table as part of my state). Is there a better way I can go about adding this feature, or a simple method for determining the correct move applicable to the current situation with what I have already done?

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  • Are there any libraries for parsing "number expressions" like 1,2-9,33- in Java

    - by mihi
    Hi, I don't think it is hard, just tedious to write: Some small free (as in beer) library where I can put in a String like 1,2-9,33- and it can tell me whether a given number matches that expression. Just like most programs have in their print range dialogs. Special functions for matching odd or even numbers only, or matching every number that is 2 mod 5 (or something like that) would be nice, but not needed. The only operation I have to perform on this list is whether the range contains a given (nonnegative) integer value; more operations like max/min value (if they exist) or an iterator would be nice, of course. What would be needed that it does not occupy lots of RAM if anyone enters 1-10000000 but the only number I will ever query is 12345 :-) (To implement it, I would parse a list into several (min/max/value/mod) pairs, like 1,10,0,1 for 1-10 or 11,33,1,2 for 1-33odd, or 12,62,2,10 for 12-62/10 (i. e. 12, 22, 32, ..., 62) and then check each number for all the intervals. Open intervals by using Integer.MaxValue etc. If there are no libs, any ideas to do it better/more efficient?)

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  • Socket isn't listed by netstat unless using certain ports

    - by illuzive
    I'm a computer science student with a few years of programming experience. Yesterday, while working on a project (Mac OS X, BSD sockets) at school, I encountered a strange problem. I was adding several modules to a very basic "server" (mostly a bunch of functions to set up and manage an UDP socket on a certain port). While doing this, I started the server from time to time in order to see that everything worked like it should. I've been using port 32000 during the development of the server. When I start the server and run netstat, the socket is listed as expected. > netstat -p UDP | grep 32000 udp46 0 0 *.32000 *.* However, when I run the server on other ports (random (10000 - 50000)), it's not listed by netstat. My thought was that I had somehow hard coded the port somewhere in the code, but that's not the case. The thing is - I can connect to the socket on any of the tested ports, and it reads data sent to it without any problem at all. It just doesn't get listed by netstat. What I wonder, is if anyone of you have any idea of why this happens? Note: Although this is a project at school, it's not homework. This is just something I want to understand for my own benefit.

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  • How to determine which inheriting class is using an abstract class's methods.

    - by Kin
    In my console application have an abstract Factory class "Listener" which contains code for listening and accepting connections, and spawning client classes. This class is inherited by two more classes (WorldListener, and MasterListener) that contain more protocol specific overrides and functions. I also have a helper class (ConsoleWrapper) which encapsulates and extends System.Console, containing methods for writing to console info on what is happening to instances of the WorldListener and MasterListener. I need a way to determine in the abstract ListenerClass which Inheriting class is calling its methods. Any help with this problem would be greatly appreciated! I am stumped :X Simplified example of what I am trying to do. abstract class Listener { public void DoSomething() { if(inheriting class == WorldListener) ConsoleWrapper.WorldWrite("Did something!"); if(inheriting class == MasterListener) ConsoleWrapper.MasterWrite("Did something!"); } } public static ConsoleWrapper { public void WorldWrite(string input) { System.Console.WriteLine("[World] {0}", input); } } public class WorldListener : Listener { public void DoSomethingSpecific() { ConsoleWrapper.WorldWrite("I did something specific!"); } } public void Main() { new WorldListener(); new MasterListener(); } Expected output [World] Did something! [World] I did something specific! [Master] Did something! [World] I did something specific!

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  • AJAX Post Not Sending Data?

    - by Jascha
    I can't for the life of me figure out why this is happening. This is kind of a repost, so forgive me, but I have new data. I am running a javascript log out function called logOut() that has make a jQuery ajax call to a php script... function logOut(){ var data = new Object; data.log_out = true; $.ajax({ type: 'POST', url: 'http://www.mydomain.com/functions.php', data: data, success: function() { alert('done'); } }); } the php function it calls is here: if(isset($_POST['log_out'])){ $query = "INSERT INTO `token_manager` (`ip_address`) VALUES('logOutSuccess')"; $connection->runQuery($query); // <-- my own database class... // omitted code that clears session etc... die(); } Now, 18 hours out of the day this works, but for some reason, every once in a while, the POST data will not trigger my query. (this will last about an hour or so). I figured out the post data is not being set by adding this at the end of my script... $query = "INSERT INTO `token_manager` (`ip_address`) VALUES('POST FAIL')"; $connection->runQuery($query); So, now I know for certain my log out function is being skipped because in my database is the following data: if it were NOT being skipped, my data would show up like this: I know it is being skipped for two reasons, one the die() at the end of my first function, and two, if it were a success a "logOutSuccess" would be registered in the table. Any thoughts? One friend says it's a janky hosting company (hostgator.com). I personally like them because they are cheap and I'm a fan of cpanel. But, if that's the case??? Thanks in advance. -J

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  • How to modify Keyboard interrupt (under Windows XP) from a C++ Program ?

    - by rockr90
    Hi everyone ! We have been given a little project (As part of my OS course) to make a Windows program that modifies keyboard input, so that it transforms any lowercase character entered into an uppercase one (without using caps-lock) ! so when you type on the keyboard you'll see what you're typing transformed into uppercase ! I have done this quite easily using Turbo C by calling geninterrupt() and using variables _AH, _AL, i had to read a character using: _AH = 0x07; // Reading a character without echo geninterrupt(0x21); // Dos interrupt Then to transform it into an Upercase letter i have to mask the 5th bit by using: _AL = _AL & 0xDF; // Masking the entered character with 11011111 and then i will display the character using any output routine. Now, this solution will only work under old C DOS compilers. But what we intend to do is to make a close or similar solution to this by using any modern C/C++ compiler under Windows XP ! What i have first thought of is modifying the Keyboard ISR so that it masks the fifth bit of any entered character to turn it uppercase ! But i do not know how exactly to do this. Second, I wanted to create a Win32 console program to either do the same solution (but to no avail) or make a windows-compatible solution, still i do not know which functions to use ! Third I thought to make a windows program that modifies the ISR directly to suit my needs ! and i'm still looking for how to do this ! So please, If you could help me out on this, I would greatly appreciate it ! Thank you in advance ! (I'm using Windows XP on intel X86 with mingw-GCC compiler.)

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  • C++ Implicit Conversion Operators

    - by Imbue
    I'm trying to find a nice inheritance solution in C++. I have a Rectangle class and a Square class. The Square class can't publicly inherit from Rectangle, because it cannot completely fulfill the rectangle's requirements. For example, a Rectangle can have it's width and height each set separately, and this of course is impossible with a Square. So, my dilemma. Square obviously will share a lot of code with Rectangle; they are quite similar. For examlpe, if I have a function like: bool IsPointInRectangle(const Rectangle& rect); it should work for a square too. In fact, I have a ton of such functions. So in making my Square class, I figured I would use private inheritance with a publicly accessible Rectangle conversion operator. So my square class looks like: class Square : private Rectangle { public: operator const Rectangle&() const; }; However, when I try to pass a Square to the IsPointInRectangle function, my compiler just complains that "Rectangle is an inaccessible base" in that context. I expect it to notice the Rectangle operator and use that instead. Is what I'm trying to do even possible? If this can't work I'm probably going to refactor part of Rectangle into MutableRectangle class. Thanks.

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  • Object equality in context of hibernate / webapp

    - by bert
    How do you handle object equality for java objects managed by hibernate? In the 'hibernate in action' book they say that one should favor business keys over surrogate keys. Most of the time, i do not have a business key. Think of addresses mapped to a person. The addresses are keeped in a Set and displayed in a Wicket RefreshingView (with a ReuseIfEquals strategy). I could either use the surrogate id or use all fields in the equals() and hashCode() functions. The problem is that those fields change during the lifetime ob the object. Either because the user entered some data or the id changes due to JPA merge() being called inside the OSIV (Open Session in View) filter. My understanding of the equals() and hashCode() contract is that those should not change during the lifetime of an object. What i have tried so far: equals() based on hashCode() which uses the database id (or super.hashCode() if id is null). Problem: new addresses start with an null id but get an id when attached to a person and this person gets merged() (re-attached) in the osiv-filter. lazy compute the hashcode when hashCode() is first called and make that hashcode @Transitional. Does not work, as merge() returns a new object and the hashcode does not get copied over. What i would need is an ID that gets assigned during object creation I think. What would be my options here? I don't want to introduce some additional persistent property. Is there a way to explicitly tell JPA to assign an ID to an object? Regards

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  • File streaming in PHP - How to replicate this C#.net code in PHP?

    - by openid_kenja
    I'm writing an interface to a web service where we need to upload configuration files. The documentation only provides a sample in C#.net which I am not familiar with. I'm trying to implement this in PHP. Can someone familiar with both languages point me in the right direction? I can figure out all the basics, but I'm trying to figure out suitable PHP replacements for the FileStream, ReadBytes, and UploadDataFile functions. I believe that the RecService object contains the URL for the web service. Thanks for your help! private void UploadFiles() { clientAlias = “<yourClientAlias>”; string filePath = “<pathToYourDataFiles>”; string[] fileList = {"Config.txt", "ProductDetails.txt", "BrandNames.txt", "CategoryNames.txt", "ProductsSoldOut.txt", "Sales.txt"}; RecommendClient RecService = new RecommendClient(); for (int i = 0; i < fileList.Length; i++) { bool lastFile = (i == fileList.Length - 1); //start generator after last file try { string fileName = filePath + fileList[i]; if (!File.Exists(fileName)) continue; // file not found } // set up a file stream and binary reader for the selected file and convert to byte array FileStream fStream = new FileStream(fileName, FileMode.Open, FileAccess.Read); BinaryReader br = new BinaryReader(fStream); byte[] data = br.ReadBytes((int)numBytes); br.Close(); // pass byte array to the web service string result = RecService.UploadDataFile(clientAlias, fileList[i], data, lastFile); fStream.Close(); fStream.Dispose(); } catch (Exception ex) { // log an error message } } }

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  • How Can I Find a List of All Exceptions That a Given Library Function Throws in Python?

    - by b14ck
    Sorry for the long title, but it seems most descriptive for my question. Basically, I'm having a difficult time finding exception information in the official python documentation. For example, in one program I'm currently writing, I'm using the shutil libary's move function: from shutil import move move('somefile.txt', '/tmp/somefile.txt') That works fine, as long as I have write access to /tmp/, there is enough diskspace, and if all other requirements are satisfied. However, when writing generic code, it is often difficult to guarantee those factors, so one usually uses exceptions: from shutil import move try: move('somefile.txt', '/tmp/somefile.txt') except: print 'Move failed for some reason.' I'd like to actually catch the appropriate exceptions thrown instead of just catching everything, but I simply can't find a list of exceptions thrown for most python modules. Is there a way for me to see which exceptions a given function can throw, and why? This way I can make appropriate cases for each exception, eg: from shutil import move try: move('somefile.txt', '/tmp/somefile.txt') except PermissionDenied: print 'No permission.' except DestinationDoesNotExist: print "/tmp/ doesn't exist" except NoDiskSpace: print 'No diskspace available.' Answer points go to whoever can either link me to some relevant documentation that I've somehow overlooked in the official docs, or provide a sure-fire way to figure out exactly which exceptions are thrown by which functions, and why. Thanks!

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  • Improving File Read Performance (single file, C++, Windows)

    - by david
    I have large (hundreds of MB or more) files that I need to read blocks from using C++ on Windows. Currently the relevant functions are: errorType LargeFile::read( void* data_out, __int64 start_position, __int64 size_bytes ) const { if( !m_open ) { // return error } else { seekPosition( start_position ); DWORD bytes_read; BOOL result = ReadFile( m_file, data_out, DWORD( size_bytes ), &bytes_read, NULL ); if( size_bytes != bytes_read || result != TRUE ) { // return error } } // return no error } void LargeFile::seekPosition( __int64 position ) const { LARGE_INTEGER target; target.QuadPart = LONGLONG( position ); SetFilePointerEx( m_file, target, NULL, FILE_BEGIN ); } The performance of the above does not seem to be very good. Reads are on 4K blocks of the file. Some reads are coherent, most are not. A couple questions: Is there a good way to profile the reads? What things might improve the performance? For example, would sector-aligning the data be useful? I'm relatively new to file i/o optimization, so suggestions or pointers to articles/tutorials would be helpful.

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  • Trait, FunctionN, or trait-inheriting-FunctionN in Scala?

    - by Willis Blackburn
    I have a trait in Scala that has a single method. Call it Computable and the single method is compute(input: Int): Int. I can't figure out whether I should Leave it as a standalone trait with a single method. Inherit from (Int = Int) and rename "compute" to "apply." Just get rid of Computable and use (Int = Int). A factor in favor of it being a trait is that I could usefully add some additional methods. But of course if they were all implemented in terms of the compute method then I could just break them out into a separate object. A factor in favor of just using the function type is simplicity and the fact that the syntax for an anonymous function is more concise than that for an anonymous Computable instance. But then I've no way to distinguish objects that are actually Computable instances from other functions that map Int to Int but aren't meant to be used in the same context as Computable. How do other people approach this type of problem? No right or wrong answers here; I'm just looking for advice.

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  • Program structure in long running data processing python script

    - by fmark
    For my current job I am writing some long-running (think hours to days) scripts that do CPU intensive data-processing. The program flow is very simple - it proceeds into the main loop, completes the main loop, saves output and terminates: The basic structure of my programs tends to be like so: <import statements> <constant declarations> <misc function declarations> def main(): for blah in blahs(): <lots of local variables> <lots of tightly coupled computation> for something in somethings(): <lots more local variables> <lots more computation> <etc., etc.> <save results> if __name__ == "__main__": main() This gets unmanageable quickly, so I want to refactor it into something more manageable. I want to make this more maintainable, without sacrificing execution speed. Each chuck of code relies on a large number of variables however, so refactoring parts of the computation out to functions would make parameters list grow out of hand very quickly. Should I put this sort of code into a python class, and change the local variables into class variables? It doesn't make a great deal of sense tp me conceptually to turn the program into a class, as the class would never be reused, and only one instance would ever be created per instance. What is the best practice structure for this kind of program? I am using python but the question is relatively language-agnostic, assuming a modern object-oriented language features.

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