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  • How operator oveloading works

    - by Rasmi Ranjan Nayak
    I have below code class rectangle { ..... .....//Some code int operator+(rectangle r1) { return(r1.length+length); } }; In main fun. int main() { rectangle r1(10,20); rectangle r2(40,60); rectangle r3(30,60); int len = r1+r3; } Here if we will see in operator+(), we are doing r1.length + length. How the compiler comes to know that the 2nd length in return statement belong to object r3 not to r1 or r2? I think answer may be in main() we have writeen int len = r1+r3; If that is the case then why do we need to write in operator+(....) { r1.lenth + lenth; //Why not length + length? } Why not length + length? Bcause compiler already knows from main() that the first length belong to object r1 and 2nd to object r3.

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  • GlassFish 3: how do you change the (default) logging format?

    - by Kawu
    The question originated from here: http://www.java.net/forum/topic/glassfish/glassfish/configuring-glassfish-logging-format - without an answer. The default GlassFish 3 logging format of is very annoying, much too long. [#|2012-03-02T09:22:03.165+0100|SEVERE|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=113;_ThreadName=AWT-EventQueue-0;| MESSAGE... ] This is just a horrible default IMO. The docs just explain all the fields, but not how to change the format: http://docs.oracle.com/cd/E18930_01/html/821-2416/abluk.html Note, that I deploy SLF4J along with my webapp which should pick up the format as well. How do you change the logging format? FYI: The links here are outdated: Install log formater in glassfish... The question here hasn't been answered: How to configure GlassFish logging to show milliseconds in timestamps?... The posting here resulted in nothing: http://www.java.net/forum/topic/glassfish/glassfish/cant-seem-configure-... It looks like GlassFish logging configuration is an issue of its own. Can anybody help?

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  • C# parameter count mismatch when trying to add AsyncCallback into BeginInvoke()

    - by PunX
    I have main form (PrenosForm) and I am trying to run Form2 asynchronously. It works without callback delegate: this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. Doesn't work with callback delegate (parameter count mismatch): this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count mismatch 2. Works with callback delegate if I do it like this: cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. My question is why does one way work and the other doesn't? I'm new at this. Would anyone be so kind as to answer my question and point out my mistakes? private delegate void copyDelegat(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt); private delegate void callBackDelegat(IAsyncResult a); public void doCopy(List<ListViewItem> datoteke, string path, PrenosForm forma, DragDropEffects efekt) { new Form2(datoteke, path, forma, efekt); } public void callBackFunc(IAsyncResult a) { AsyncResult res = a.AsyncState as AsyncResult; copyDelegat delegat = res.AsyncDelegate as copyDelegat; delegat.EndInvoke(a); } public void kopiraj(List<ListViewItem> datoteke, DragDropEffects efekt) { copyDelegat cp = new copyDelegat(doCopy); callBackDelegat callBackDelegate = new callBackDelegat(callBackFunc); this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, new AsyncCallback(callBackDelegate), null); //doesn't work parameter count missmatch 2. this.BeginInvoke(cp, new object[] { datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt }, null); //works 1. cp.BeginInvoke(datoteke, this.treeView1.SelectedNode.FullPath.ToString(), this, efekt, new AsyncCallback(callBackDelegate), null); //works 3. }

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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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  • To what extent should code try to explain fatal exceptions?

    - by Andrzej Doyle
    I suspect that all non-trivial software is likely to experience situations where it hits an external problem it cannot work around and thus needs to fail. This might be due to bad configuration, an external server being down, disk full, etc. In these situations, especially if the software is running in non-interactive mode, I expect that all one can really do is log an error and wait for the admin to read the logs and fix the problem. If someone happens to interact with the software in the meantime, e.g. a request comes in to a server that failed to initialize properly, then perhaps an appropriate hint can be given to check the logs and maybe even the error can be echoed (depending on whether you can tell if they're a technical guy as opposed to a business user). For the moment though let's not think too hard about this part. My question is, to what extent should the software be responsible for trying to explain the meaning of the fatal error? In general, how much competence/knowledge are you allowed to presume on administrators of the software, and how much should you include troubleshooting information and potential resolution steps when logging fatal errors? Of course if there's something that's unique to the runtime context this should definitely be logged; but lets assume your software needs to talk to Active Directory via LDAP and gets back an error "[LDAP: error code 49 - 80090308: LdapErr: DSID-0C090334, comment: AcceptSecurityContext error, data 525, vece]". Is it reasonable to assume that the maintainers will be able to Google the error code and work out what it means, or should the software try to parse the error code and log that this is caused by an incorrect user DN in the LDAP config? I don't know if there is a definitive best-practices answer for this, so I'm keen to hear a variety of views.

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  • Compact data structure for storing a large set of integral values

    - by Odrade
    I'm working on an application that needs to pass around large sets of Int32 values. The sets are expected to contain ~1,000,000-50,000,000 items, where each item is a database key in the range 0-50,000,000. I expect distribution of ids in any given set to be effectively random over this range. The operations I need on the set are dirt simple: Add a new value Iterate over all of the values. There is a serious concern about the memory usage of these sets, so I'm looking for a data structure that can store the ids more efficiently than a simple List<int>or HashSet<int>. I've looked at BitArray, but that can be wasteful depending on how sparse the ids are. I've also considered a bitwise trie, but I'm unsure how to calculate the space efficiency of that solution for the expected data. A Bloom Filter would be great, if only I could tolerate the false negatives. I would appreciate any suggestions of data structures suitable for this purpose. I'm interested in both out-of-the-box and custom solutions. EDIT: To answer your questions: No, the items don't need to be sorted By "pass around" I mean both pass between methods and serialize and send over the wire. I clearly should have mentioned this. There could be a decent number of these sets in memory at once (~100).

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  • iPhone OpenGL ES Texture2D Masking

    - by Robert Neagu
    What's the best choice when trying to mask a texture like ColorSplash or other apps like iSteam, etc? I started learning OPENGL ES like... 4 days ago (I'm a total rookie) and tried the following approach: 1) I created a colored texture2D, a grayscale version of the first texture and a third texture2D called mask 2) I also created a texture2D for the brush... which is grayscale and it's opaque (brush = black = 0,0,0,1 and surroundings = white = 1,1,1,1). My intention was to create an antialiased brush with smooth edges but i'm fine with a normal one right now 3) I searched for masking techniques on the internet and found this tutorial ZeusCMD - Design and Development Tutorials : OpenGL ES Programming Tutorials - Masking about masking. The tutorial tells me to use blending to achieve masking... first draw colored, then mask with glBlendFunc(GL_DST_COLOR, GL_ZERO) and then grayscale with glBlendFunc(GL_ONE, GL_ONE) ... and this gives me something close to what i want... but not exactly what i want. The result is masked but it's somehow overbright-ed 4) For drawing to the mask texture i used an extra frame buffer object (FBO) I'm not really happy with the resulting image (overbright-ed picture) nor with the speed achieved with this method. I think the normal way was to draw directly to the grayscale (overlay) texture2D affecting only it's alpha channel in the places where the brush hits. Is there a fast way to achieve this? I have searched a lot and never got an answer that's clear and understandable. Then, in the main draw loop I could only draw the colored texture and then blend the grayscale ontop with glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA). I just want to learn to use OPENGL ES and it's driving me nuts because i can't get it to work properly. An advice, a link to a tutorial would be much appreciated.

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  • Representing element as boolean with JAXB?

    - by Marcus
    We have this XML: <Summary> <ValueA>xxx</ValueA> <ValueB/> </Summary> <ValueB/> will never have any attributes or inner elements. It's a boolean type element - it exists (true) or it doesn't (false). JAXB generated a Summary class with a String valueA member, which is good. But for ValueB, JAXB generated a ValueB inner class and a corresponding member: @XmlElement(name = "ValueB") protected Summary.ValueB valueB; But what I'd like is a boolean member and no inner class: @XmlElement(name = "ValueB") protected boolean valueB; How can you do this? I'm not looking to regenerate the classes, I'd like to just make the code change manually. Update: In line with the accepted answer, we created a new method returning the boolean value conditional on whether valueB == null. As we are using Hibernate, we annotated valueB with @Transient and annotated the boolean getter with Hibernate's @Column annotation.

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  • How to configure a subproject dependency in Maven without deploying jars?

    - by MikeHoss
    I googled this and it seems that no one has an answer, yet it seems like such an elementary thing that it should be possible. I have the following project structure: parent ---sub-project1 ---sub-project2 sub-project2 needs to have sub-project1 as a dependency. So I have this in sub-project2's pom: <dependencies> <dependency> <artifactId>sub-project1</artifactId> <groupId>mygroup</groupId> <version>1.0-SNAPSHOT</version> </dependency> .... When I do this, Maven tries to dowload the sub-project1.jar file, which does not exist because it's not ready for the repo yet. I tried to put a <scope>import</scope> in the dependency, but that didn't work either -- same result. So what do I have to do to get Maven to look at sub-project1 when building sub-project2?

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  • How do I ensure a Flex dataProvider processes the data synchronously?

    - by Matt Calthrop
    I am using an component, and currently have a dataProvider working that is an ArrayCollection (have a separate question about how to make this an XML file... but I digress). Variable declaration looks like this: [Bindable] private var _dpImageList : ArrayCollection = new ArrayCollection([ {"location" : "path/to/image1.jpg"}, {"location" : "path/to/image2.jpg"}, {"location" : "path/to/image3.jpg"} ]); I then refer to like this: <s:List id="lstImages" width="100%" dataProvider="{_dpImageList}" itemRenderer="path.to.render.ImageRenderer" skinClass="path.to.skins.ListSkin" > <s:layout> <s:HorizontalLayout gap="2" /> </s:layout> </s:List> Currently, it would appear that each item is processed asynchronously. However, I want them to be processed synchronously. Reason: I am displaying a list of images, and I want the leftmost one rendered first, followed by the one to its right, and so on. Edit: I just found this answer. Do you think that could be the same issue?

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  • Using border-radius on ul with only giving a radius to the outer li's

    - by RJD22
    Maybe the answer is really simple. But what I'm trying to do it to make a curved border around the li's. So not only the outside but also the inside: Examples: Right Wrong: Don't mind the differences. What I'm trying to do it to curve the inner border this is the html: <ul> <li>Dashboard</li> <li>Voertuigen</li> <li>Klanten</li> <li>Factures</li> <li>Boetes</li> <li>Onderhoud</li> </ul> Css: ul { list-style: none; -moz-border-radius: 12px; -webkit-border-radius: 12px; width: 140px; border: 10px solid #BEBEBE; } ul li { height: 40px; width: 140px; background: #E5E5E5; }

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  • C# Virtual method call in constructor - how to refactor?

    - by Cristi Diaconescu
    I have an abstract class for database-agnostic cursor actions. Derived from that, there are classes that implement the abstract methods for handling database-specific stuff. The problem is, the base class ctor needs to call an abstract method - when the ctor is called, it needs to initialize the database-specific cursor. I know why this shouldn't be done, I don't need that explanation! This is my first implementation, that obviously doesn't work - it's the textbook "wrong way" of doing it. The overridden method accesses a field from the derived class, which is not yet instantiated: public abstract class CursorReader { private readonly int m_rowCount; protected CursorReader() { m_rowCount = CreateCursor(sqlCmd); //virtual call ! } protected abstract int CreateCursor(string sqlCmd); } public class SqlCursorReader : CursorReader { private SqlConnection m_sqlConnection; public SqlCursorReader(string sqlCmd, SqlConnection sqlConnection) { m_sqlConnection = sqlConnection; //field initialized here } protected override int CreateCursor(string sqlCmd) { //uses not-yet-initialized member *m_sqlConnection* //so this throws a NullReferenceException var cursor = new CustomCursor(sqlCmd, m_sqlConnection); return cursor.Count(); } } I will follow up with an answer on my attempts to fix this...

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  • Converting ntext to nvcharmax(max) - Getting around size limitation

    - by Overflew
    Hi all, I'm trying to change an existing SQL NText column to nvcharmax(max), and encountering an error on the size limit. There's a large amount of existing data, some of which is more than the 8k limit, I believe. We're looking to convert this, so that the field is searchable in LINQ. The 2x SQL statements I've tried are: update Table set dataNVarChar = convert(nvarchar(max), dataNtext) where dataNtext is not null update Table set dataNVarChar = cast(dataNtext as nvarchar(max)) where dataNtext is not null And the error I get is: Cannot create a row of size 8086 which is greater than the allowable maximum row size of 8060. This is using SQL Server 2008. Any help appreciated, Thanks. Update / Solution: The marked answer below is correct, and SQL 2008 can change the column to the correct data type in my situation, and there are no dramas with the LINQ-utilising application we use on top of it: alter table [TBL] alter column [COL] nvarchar(max) I've also been advised to follow it up with: update [TBL] set [COL] = [COL] Which completes the conversion by moving the data from the lob structure to the table (if the length in less than 8k), which improves performance / keeps things proper.

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  • In Inform 7, is it possible to use a second noun construct with "pull"?

    - by Beska
    I'll eat my hat if I get a good answer to this...I suspect that although I'm a rank beginner in Inform 7, and I'm guessing this isn't that hard, but there are probably not many people here who are familiar with Inform 7. Still, nothing ventured... I'm trying to create a custom response to a "pull" action. Unfortunately, I think the "pull" action doesn't normally expect a second noun. So I'm trying something like this: The nails are some things in the Foyer. The nails are scenery. Instead of pulling the nails: If the second noun is nothing: say "How? Are you going to pull the nails with your teeth?"; otherwise: say "I don't think that's going to do the job." But while this compiles, and the first part works, the "I don't think..." section is never called...the interpreter just responds "I only understood you as far as wanting to pull the nails." Do I have to create my own custom action for this? Overwrite the standard pull action? Am I missing something simple that will allow me to get this to work?

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  • Parse a CSV file using python (to make a decision tree later)

    - by Margaret
    First off, full disclosure: This is going towards a uni assignment, so I don't want to receive code. :). I'm more looking for approaches; I'm very new to python, having read a book but not yet written any code. The entire task is to import the contents of a CSV file, create a decision tree from the contents of the CSV file (using the ID3 algorithm), and then parse a second CSV file to run against the tree. There's a big (understandable) preference to have it capable of dealing with different CSV files (I asked if we were allowed to hard code the column names, mostly to eliminate it as a possibility, and the answer was no). The CSV files are in a fairly standard format; the header row is marked with a # then the column names are displayed, and every row after that is a simple series of values. Example: # Column1, Column2, Column3, Column4 Value01, Value02, Value03, Value04 Value11, Value12, Value13, Value14 At the moment, I'm trying to work out the first part: parsing the CSV. To make the decisions for the decision tree, a dictionary structure seems like it's going to be the most logical; so I was thinking of doing something along these lines: Read in each line, character by character If the character is not a comma or a space Append character to temporary string If the character is a comma Append the temporary string to a list Empty string Once a line has been read Create a dictionary using the header row as the key (somehow!) Append that dictionary to a list However, if I do things that way, I'm not sure how to make a mapping between the keys and the values. I'm also wondering whether there is some way to perform an action on every dictionary in a list, since I'll need to be doing things to the effect of "Everyone return their values for columns Column1 and Column4, so I can count up who has what!" - I assume that there is some mechanism, but I don't think I know how to do it. Is a dictionary the best way to do it? Would I be better off doing things using some other data structure? If so, what?

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  • Request size limitation when using MultipartHttpServletRequest of Spring 3.0

    - by Spiderman
    I'd like to know what is the size limitation if I upload list of files in one client's form submition using HTTP multipart content type. On the server side I am using Spring's MultipartHttpServletRequest to handle the request. mM questions: Is there should be different file size limitation and total request size limitation or file size is the only limitation and the request is capable of uploading 100s of files as lonng as they are not too large. Doest the Spring request wrapper read the complete request and store it in the JAVA heap memory or it store temporaray files of it to be able to use big quota. Is the use of reading the httpservlet request in streaming would change the size limitation than using complete http request read at-once by the application server. What is the bottleneck of this process - Java heap size, the quota of the filesystem on which my web-server runs, the maximum allowed BLOB size that the DataBase in which I am gonna save the file alows? or Spring internal limitations? Related threads that still don't have exact answer to this: does-spring-framework-support-streaming-mode-in-mutlipart-requests is-there-a-way-to-get-raw-http-request-stream-from-java-servlet-handler how-to- drop-body-of-a-request-after-checking-headers-in-servlet apache-commons-fileupload-throws-malformedstreamexception

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  • Which languages support class replacement?

    - by Alix
    Hi, I'm writing my master thesis, which deals with AOP in .NET, among other things, and I mention the lack of support for replacing classes at load time as an important factor in the fact that there are currently no .NET AOP frameworks that perform true dynamic weaving -- not without imposing the requirement that woven classes must extend ContextBoundObject or MarshalByRefObject or expose all their semantics on an interface. You can however do this in Java thanks to ClassFileTransformer: You extend ClassFileTransformer. You subscribe to the class load event. On class load, you rewrite the class and replace it. All this is very well, but my project director has asked me, quite in the last minute, to give him a list of languages that do / do not support class replacement. I really have no time to look for this now: I wouldn't feel comfortable just doing a superficial research and potentially putting erroneous information in my thesis. So I ask you, oh almighty programming community, can you help out? Of course, I'm not asking you to research this yourselves. Simply, if you know for sure that a particular language supports / doesn't support this, leave it as an answer. If you're not sure please don't forget to point it out. Thanks so much!

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  • Type errors when using same name

    - by lykimq
    I have 3 files: 1) cpf0.ml type string = char list type url = string type var = string type name = string type symbol = | Symbol_name of name 2) problem.ml: type symbol = | Ident of string 3) test.ml open Problem;; open Cpf0;; let symbol b = function | Symbol_name n -> Ident n When I combine test.ml: ocamlc -c test.ml. I received an error: This expression has type Cpf0.name = char list but an expression was expected of type string Could you please help me to correct it? Thank you very much EDIT: Thank you for your answer. I want to explain more about these 3 files: Because I am working with extraction in Coq to Ocaml type: cpf0.ml is generated from cpf.v : Require Import String. Definition string := string. Definition name := string. Inductive symbol := | Symbol_name : name -> symbol. The code extraction.v: Set Extraction Optimize. Extraction Language Ocaml. Require ExtrOcamlBasic ExtrOcamlString. Extraction Blacklist cpf list. where ExtrOcamlString I opened: open Cpf0;; in problem.ml, and I got a new problem because in problem.ml they have another definition for type string This expression has type Cpf0.string = char list but an expression was expected of type Util.StrSet.elt = string Here is a definition in util.ml defined type string: module Str = struct type t = string end;; module StrOrd = Ord.Make (Str);; module StrSet = Set.Make (StrOrd);; module StrMap = Map.Make (StrOrd);; let set_add_chk x s = if StrSet.mem x s then failwith (x ^ " already declared") else StrSet.add x s;; I was trying to change t = string to t = char list, but if I do that I have to change a lot of function it depend on (for example: set_add_chk above). Could you please give me a good idea? how I would do in this case.

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  • Expanding DIV slides behind DIV beneath it...

    - by Paddy
    I'm not sure that I'm going to get an answer here, as I'd need to post a lot of CSS and html to get a working recreation, however... I have structure something like this: <fieldset> <legend>Test A</legend> <h3>Test A</h3> <p> Something here. </p> <div style="display:hidden;">I'm dynamically displayed</div> </fieldset> <fieldset> <legend>Test B</legend> <h3>Test B</h3> <p> Something B here. </p> </fieldset> I have code that toggles the display of my hidden div using jQuery and .show(). This works fine in IE8, firefox and Safari, but when I stick IE8 into compatibility mode, then the first fieldset (Test A) will expand, but the expansion happens behind the second fieldset, which doesn't move (i.e. it slides down behind it). I have quite a bit of CSS in use here, and I'm going to have to go back and unpick the whold lot, which isn't a fun idea. If anybody has any idea of one of the IE7 rendering issues that might be affecting this, then I'd very much appreciate it. (note that there is more to the content in these fieldsets than shown, including floated divs). Quick note - if I stick IE7 into quirks mode, it works (but wrecks the rest of my layout) - in standards mode, I get the above behaviour.

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  • Is there some formal way to update the browser detection files for ASP.Net?

    - by Deane
    I have an ASP.Net site on which we're using control adapters. We have the adapters mapped to a "refID" of "Default." These adapters are working fine on all browsers except Chrome and Safari. For those browsers, they do not execute. I've given up trying to figure out why -- I have a question here on SO that no one has been able to answer, and I've been researching it for days now. It's just inexplicable. I have tested the same code in my local environment, and it works just fine. Additionally, no one else can replicate my problem on other servers. It seems to be somehow confined to the machines at my client's site. Could they be somehow out-of-date? If this is the case, is there some way to "update" the .browser files? I'm half-tempted to just copy the .browser files out of the Framework directory from my machine over to theirs, but I'm curious is there's something more formal than this? Is there some other source of data that ASP.Net uses for browser detection other than these files?

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  • Paperclip failing to upload on specific scaffold, yet works on others

    - by Saifis
    I know there are tons of questions about paperclip, but I failed to find the answer to my problem. I know its prob just something simple, but I I'm running out of hair to pull out. I have paperclip working on other parts of my project, they work with no problem, however, a certain scaffold fails to upload, all the attributes to the uploaded file are nil. Here are the relevant information. Model: has_attached_file :foo, :styles => { :thumb => "140x140>" }, :url => "/data/:id/:style/:basename.:extension", :path => ":rails_root/public/data/:id/:style/:basename.:extension" View: <% form_for(@bar, :html => { :multipart => true }) do |f| %> <%= f.error_messages %> ---------- <li><%= f.label :top %> <%= f.file_field :foo %></li> ---------- <ul><%= f.submit "Save" %></ul> <% end %> Also, comparing the logs to the parts that work, the :foo attribute seems to be passing different values than in the ones that work. In the logs, when the paperclip function works, it looks like this "image"=>#<File:/var/folders/M5/M5HEb+WhFxmqNDGH5s-pNE+++TI/-Tmp-/RackMultipart20100512-1302-5e2e6e-0> when it does not, it seems to pass the file name directly "foo"=>"foo_image.png" I am developing locally on MacOSX using local rails and ruby libs.

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  • Achieving Thread-Safety

    - by Smasher
    Question How can I make sure my application is thread-safe? Are their any common practices, testing methods, things to avoid, things to look for? Background I'm currently developing a server application that performs a number of background tasks in different threads and communicates with clients using Indy (using another bunch of automatically generated threads for the communication). Since the application should be highly availabe, a program crash is a very bad thing and I want to make sure that the application is thread-safe. No matter what, from time to time I discover a piece of code that throws an exception that never occured before and in most cases I realize that it is some kind of synchronization bug, where I forgot to synchronize my objects properly. Hence my question concerning best practices, testing of thread-safety and things like that. mghie: Thanks for the answer! I should perhaps be a little bit more precise. Just to be clear, I know about the principles of multithreading, I use synchronization (monitors) throughout my program and I know how to differentiate threading problems from other implementation problems. But nevertheless, I keep forgetting to add proper synchronization from time to time. Just to give an example, I used the RTL sort function in my code. Looked something like FKeyList.Sort (CompareKeysFunc); Turns out, that I had to synchronize FKeyList while sorting. It just don't came to my mind when initially writing that simple line of code. It's these thins I wanna talk about. What are the places where one easily forgets to add synchronization code? How do YOU make sure that you added sync code in all important places?

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  • Modifying C# dictionary value

    - by minjang
    I'm a C++ expert, but not at all for C#. I created a Dictionary<string, STATS>, where STATS is a simple struct. Once I built the dictionary with initial string and STATS pairs, I want to modify the dictionary's STATS value. In C++, it's very clear: Dictionary<string, STATS*> benchmarks; Initialize it... STATS* stats = benchmarks[item.Key]; // Touch stats directly However, I tried like this in C#: Dictionary<string, STATS> benchmarks = new Dictionary<string, STATS>(); // Initialize benchmarks with a bunch of STATS foreach (var item in _data) benchmarks.Add(item.app_name, item); foreach (KeyValuePair<string, STATS> item in benchmarks) { // I want to modify STATS value inside of benchmarks dictionary. STATS stat_item = benchmarks[item.Key]; ParseOutputFile("foo", ref stat_item); // But, not modified in benchmarks... stat_item is just a copy. } This is a really novice problem, but wasn't easy to find an answer. EDIT: I also tried like the following: STATS stat_item = benchmarks[item.Key]; ParseOutputFile(file_name, ref stat_item); benchmarks[item.Key] = stat_item; However, I got the exception since such action invalidates Dictionary: Unhandled Exception: System.InvalidOperationException: Collection was modified; enumeration operation may not execute. at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource) at System.Collections.Generic.Dictionary`2.Enumerator.MoveNext() at helper.Program.Main(String[] args) in D:\dev\\helper\Program.cs:line 75

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  • Why does Android allocate more memory than needed when loading images

    - by Simon
    Folks, I don't think that this is a duplicate and is NOT one of those how do I avoid OOMs questions. This is a genuine quest for knowledge so hold off on those down votes please... Imagine I have a JPEG of 500x500 pixels. I load it as ARGB_8888 which is as "bad as it gets". I would expect Android to allocate 500x500x4 bytes = a little under 1MB however, look at a heap dump and you will see that Android allocates significantly more, often factors of 5-10 times greater. You frequently see questions on here about OOMS where the stack trace shows a heap request of say 15MB and it is ALWAYS much larger than is required simply to hold the bytes of the image. The OP usually catches some downvotes then is bombarded with stock answers and comments about using less memory (thanks Romain!) and in scaling. I think there is more than meets the eye here. Anybody know why this is? If there is no apparent answer, I will put together an SSCCE if it helps. PS. I assume that JPEG vs PNG etc is irrelevant since we're talking about the memory usage of the backing bitmap which is simply x times y times BPP - or am I being slow?

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  • Should I strip the XML declaration from suds output before parsing with lxml?

    - by mikl
    I’m trying to implement a SOAP webservice in Python 2.6 using the suds library. That is working well, but I’ve run into a problem when trying to parse the output with lxml. Suds returns a suds.sax.text.Text object with the reply from the SOAP service. The suds.sax.text.Text class is a subclass of the Python built-in Unicode class. In essence, it would be comparable with this Python statement: u'<?xml version="1.0" encoding="utf-8" ?><root><lotsofelements \></root>' Which is incongrous, since if the XML declaration is correct, the contents are UTF-8 encoded, and thus not a Python Unicode object (because those are stored in some internal encoding like UCS4). lxml will refuse to parse this, as documented, since there is no clear answer to what encoding it should be interpreted as. As I see it, there are two ways out of this bind: Strip the <?xml> declaration, including the encoding. Convert the output from Suds into a bytestring, using the specified encoding. Currently, the data I’m receiving from the webservice is within the ASCII-range, so either way will work, but both feels very much like ugly hacks to me, and I’m not quite sure what would happen, if I start to receive data that would need a wider range of Unicode characters. Any good ideas? I can’t imagine I’m the first one in this position…

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