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• Could someone explain gtk2hs drag and drop to me, the listDND.hs demo just isn't doing it for me?

  - by Tom Carstens

  As the title says, I just don't get DND (or rather I understand the concept and I understand the order of callbacks, I just don't understand how to setup DND for actual usage.) I'd like to say that I've done DND stuff before in C, but considering I never really got that working... So I'm trying (and mostly succeeding, save DND) to write a text editor (using gtksourceview, because it has built in code highlighting.) Reasons are below if you want them. Anyways, there's not really a good DND demo or tutorial available for gtk2hs (listDND.hs just doesn't translate well in my head.) So what I'm asking is for code that demonstrates simple DND on a window widget (for example.) Ideally, it should accept drops from other windows (such as Thunar) and print out the information in string form. I think I can take it from there... Reasons: I'm running a fairly light weight setup, dwm and a few gtk+2 programs. I really don't want to have to pull in gtk+3 to get the current gedit from the repos (Arch Linux.) Currently, I'm using geany for all of my text editing needs, however, geany is a bit heavy for editing config files. Further, geany doesn't care for my terminal of choice (st;) so I don't even get the benefit of using it as an IDE. Meaning I'd like a lightweight text editor with syntax highlighting. I could configure emacs or vim or something, but that seems to me to be more of a hack then a proper solution. Thus my project was born. It's mostly working (aside from DND, all that's left is proper multi-tab support.) Admittedly, I could probably work this out if I wrote it in C, but there isn't that much state in a text editor so Haskell's been working fine with almost no need for mutable variables.

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• .NET HttpModule does not send form variables to PHP file on RewritePath()

  - by jammus

  Hello friends. We have an application running on IIS 6 which uses a custom HttpModule to rewrite urls. This works great (well done us) except in the case where the Context.RewritePath destination is a .php file. The php file is executed as expected, however the $_POST collection is empty meaning it cannot access any forms which are submitted to rewritten urls. The problem does not exist when rewriting to .aspx files as the Request.Form collection is fine. My question therefore has two parts: Why is the $_POST collection not being populated? Is there a way to ensure that the .php $_POST collection is correctly populated after a rewrite? I don't have much to show in the way of code. There's just a simple: context.RewritePath(newPath); once the HttpModule has figured out where to send the request. Edit: Interestingly, if I do var_dump(file_get_contents('php://input')); in the PHP file (method described here) the contents of the form is displayed. So the data is reaching the PHP script but not the $_POST array.

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• If attacker has original data, and encrypted data, can they determine the passphrase?

  - by Brad Cupit

  If an attacker has several distinct items (for example: e-mail addresses) and knows the encrypted value of each item, can the attacker more easily determine the secret passphrase used to encrypt those items? Meaning, can they determine the passphrase without resorting to brute force? This question may sound strange, so let me provide a use-case: User signs up to a site with their e-mail address Server sends that e-mail address a confirmation URL (for example: https://my.app.com/confirmEmailAddress/bill%40yahoo.com) Attacker can guess the confirmation URL and therefore can sign up with someone else's e-mail address, and 'confirm' it without ever having to sign in to that person's e-mail account and see the confirmation URL. This is a problem. Instead of sending the e-mail address plain text in the URL, we'll send it encrypted by a secret passphrase. (I know the attacker could still intercept the e-mail sent by the server, since e-mail are plain text, but bear with me here.) If an attacker then signs up with multiple free e-mail accounts and sees multiple URLs, each with the corresponding encrypted e-mail address, could the attacker more easily determine the passphrase used for encryption? Alternative Solution I could instead send a random number or one-way hash of their e-mail address (plus random salt). This eliminates storing the secret passphrase, but it means I need to store that random number/hash in the database. The original approach above does not require this extra table. I'm leaning towards the the one-way hash + extra table solution, but I still would like to know the answer: does having multiple unencrypted e-mail addresses and their encrypted counterparts make it easier to determine the passphrase used?

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• Enforcing default time when only date in timestamptz provided

  - by Incognito

  Assume I have the table: postgres=# create table foo (datetimes timestamptz); CREATE TABLE postgres=# \d+ foo Table "public.foo" Column | Type | Modifiers | Storage | Description -----------+--------------------------+-----------+---------+------------- datetimes | timestamp with time zone | | plain | Has OIDs: no So lets insert some values into it... postgres=# insert into foo values ('2012-12-12'), --This is the value I want to catch for. (null), ('2012-12-12 12:12:12'), ('2012-12-12 12:12'); INSERT 0 4 And here's what we have: postgres=# select * from foo ; datetimes ------------------------ 2012-12-12 00:00:00+00 2012-12-12 12:12:12+00 2012-12-12 12:12:00+00 (4 rows) Ideally, I'd like to set up a default time-stamp value when a TIME is not provided with the input, rather than the de-facto time of 2012-12-12 being 00:00:00, I would like to set a default of 15:45:10. Meaning, my results should look like: postgres=# select * from foo ; datetimes ------------------------ 2012-12-12 15:45:10+00 --This one gets the default time. 2012-12-12 12:12:12+00 2012-12-12 12:12:00+00 (4 rows) I'm not really sure how to do this in postgres 8.4, I can't find anything in the datetime section of the manual or the sections regarding column default values.

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• C# Finding 2 positions 1-dimArray

  - by Chris

  Hello, In a method i am calculating the longest row of elements. The 1-dim array is filled up with random values (0 or 1). The method looks up the longest row (being 0 or 1, whatever is the longest). Meaning in for example: 1110100 --> the longest row would be 3 (3 * 1) 0110000 --> the longest row would be 4 (4 * 0) My problem is i am trying to perform some type of linear search to show the position of the row in the array. The first example has the longest row of 3 elements (3 times 1). For 1110100 the position in the array would be 0 - 2 (index) For 0110000 the position in the array would be 3 - 6 (index) I have been trying with foreaches, for loops etc..but i cannot seem to get the proper indexes of both. Cannot seem to display both positions properly. For the first example the correct output wouldbe: The largest row of same elements of the array consists of 3 elements on the position 0 - 2. The longest row of elements gets of same elements get calculated as the following: public int BerekenDeelrij (int [] table) ( int count = 0; final int value = 0; int largest = 0; foreach (int value in table) ( if (value == last value) counter + +; else ( largest = Math.Max largest (largest, counter); final value = value count = 1; ) ) Math.Max return (largest, counter); ) Best Regards.

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• Starting a code library.

  - by Rob Stevenson-Leggett

  Hi, I've been meaning to start a library of reusable code snippets for a while and never seem to get round to it. I think my main problems are: Where to start. What structure should my library take? Should it be a compiled library (where appropriate or just classes I can drop into any project? Or a library project that can be included? In my experience, a built library will quickly become out of date and the source will get lost. So I'm leaning towards source libraries that I can export from SVN and include in any project. Intellectual property. I am employeed, so a lot of the code I write is not my IP. How can I ensure that I don't give my own IP away using it on projects in work and at home? I'm thinking the best way would be to licence my library with an open source licence and make sure I only add to it in my own time using my own equipment and therefore making sure that if I use it in a work project the same rules apply as if I was using a third party library. I write in many different languages and often would require two or more parts of this library. Should I look at implementing a few template projects and a core project for each of my chosen reusable components and languages? Has anyone else got this sort of library and how do you organise and update it?

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• Catching exception in Main() method

  - by Corvin

  Consider the following simple application: a windows form created by a "new C# windows application" sequence in VS that was modified in a following way: public static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); try { Application.Run(new Form1()); } catch (Exception ex) { MessageBox.Show("An unexpected exception was caught."); } } Form1.cs contains the following modifications: private void Form1_Load(object sender, EventArgs e) { throw new Exception("Error"); } If I press F5 in IDE, then, as I expect, I see a message box saying that exception was caught and the application quits. If I go to Debug(or Release)/bin and launch the executable, I see the standard "Unhandled exception" window, meaning that my exception handler doesn't work. Obviously, that has something to do with exception being thrown from a different thread that Application.Run is called from. But the question remains - why the behavior differs depending on whether the application has been run from IDE or from command line? What is the best practice to ensure that no exceptions remain unhandled in the application?

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• Strange data swapping error occurs when I attempt to update rows in my table from another table in m

  - by Wesley

  So I have a table of data that is 10,000 lines long. Several of the columns in the table simply describe information about one of the columns, meaning, that only one column has the content, and the rest of the columns describe the location of the content (its for a book). Right now, only 6,000 of the 10,000 rows' content column is filled with its content. Rows 6-10,000's content column simply says null. I have another table in the db that has the content for rows 6,000-10,000, with the correct corresponding primary key which would (seemingly) make it easy to update the 10,000 row table. I have been trying an update query such as the following: UPDATE table(10,000) SET content_column = (SELECT content FROM table(6,000-10,000) WHERE table(10,000).id = table(6-10,000.id) Which kind of works, the only problem is that it pulls in the data from the second table just fine, but it replaces the existing content column with null. So rows 1-6,000's content column become null, and rows 6-10,000's content column have the correct values...Pretty strange I thought anyway. Does anybody have any thoughts about where I am going wrong? If you could show me a better sql query, I would appreciate it! Thanks

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• what's the performance difference between int and varchar for primary keys

  - by user568576

  I need to create a primary key scheme for a system that will need peer to peer replication. So I'm planning to combine a unique system ID and a sequential number in some way to come up with unique ID's. I want to make sure I'll never run out of ID's, so I'm thinking about using a varchar field, since I could always add another character if I start running out. But I've read that integers are better optimized for this. So I have some questions... 1) Are integers really better optimized? And if they are, how much of a performance difference is there between varchars and integers? I'm going to use firebird for now. But I may switch later. Or possibly support multiple db's. So I'm looking for generalizations, if that's possible. 2) If integers are significantly better optimized, why is that? And is it likely that varchars will catch up in the future, so eventually it won't matter anyway? My varchar keys won't have any meaning, except for the unique system ID part. But I may want to obscure that somehow. Also, I plan to efficiently use all the bits of each character. I don't, for example, plan to code the integer 123 as the character string "123". So I don't think varchars will require more space than integers.

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• In Java, is there a gain in using interfaces for complex models?

  - by Gnoupi

  The title is hardly understandable, but I'm not sure how to summarize that another way. Any edit to clarify is welcome. I have been told, and recommended to use interfaces to improve performances, even in a case which doesn't especially call for the regular "interface" role. In this case, the objects are big models (in a MVC meaning), with many methods and fields. The "good use" that has been recommended to me is to create an interface, with its unique implementation. There won't be any other class implementing this interface, for sure. I have been told that this is better to do so, because it "exposes less" (or something close) to the other classes which will use methods from this class, as these objects are referring to the object from its interface (all public method from the implementation being reproduced in the interface). This seems quite strange to me, as it seems like a C++ use to me (with header files). There I see the point, but in Java? Is there really a point in making an interface for such unique implementation? I would really appreciate some clarifications on the topic, so I could justify not following such kind of behavior, and the hassle it creates from duplicating all declarations.

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• jquery : ul, li parent multiple child sub-child toggling

  - by user360826

  hello, my main question is as follows: how to show only the first subchild of a ul or li upon clicking the enclosing parent. eg: <ul> Grandparent <li> Child1 <li> Grandchild11</li></li> <li> Child2 <li>GrandChild21</li><li>grandchild22</li></li> </ul> so, for example I would like something to the effect of <script> $('ul').click(function(){ $('ul').children('first li').toggle() }); $('li').click(function(){ $('li').children('first li').toggle() }); </script> meaning: when i click ul, i only see the first child node (child1 and child2 will be shown, but not the grandchildren). when i click child1 or child2 i see the respective grandchild. grandchild is not shown upon clicking grandparent, only upon clicking child1 or child2. i know i am reinventing the wheel of some pre-coded solution, but any help would be largely appreciated!

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• Question regarding parent/child relationships with dynamically generated checkboxes using jquery

  - by Jeff

  I have a form of checkboxes, that is dynamically generated based on the users content. Sections of checkboxes are broken up by categories, and each category has projects within. For database purposes, the category values have checkboxes, that are hidden. IF a category has sub items that have checkboxes that are checked, THEN the category checkbox is checked as well. I have gotten this working ok using the JQuery .click(), but I can't figure out how to do it when the page loads. Here is my code for when a checkbox is actually clicked: $(".project").click(function() { if($(this).is(":checked") && $(this).hasClass("project")) { $(this).parent().parent().children(':first').attr('checked', true); }else if(!$(this).parent().children('.project').is(":checked")){ $(this).parent().parent().children(':first').attr('checked', false); } }); Now when I am editing the status of these boxes (meaning after they have been saved to the db) the category boxes are not showing up as checked even though their children projects are checked. What can I do to make it so that my category box will be checked at load time if that category's child is checked? Part of the problem I think is with the dynamically changing parent child setup, how can I find the parent box in order to have it checked? Thanks!

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• Is there programming language with better approach for switch's break statements ?

  - by Vitaly Polonetsky

  It's the same syntax in a way too many languages: switch (someValue) { case OPTION_ONE: case OPTION_LIKE_ONE: case OPTION_ONE_SIMILAR: doSomeStuff1(); break; // EXIT the switch case OPTION_TWO_WITH_PRE_ACTION: doPreActionStuff2(); // the default is to CONTINUE to next case case OPTION_TWO: doSomeStuff2(); break; // EXIT the switch case OPTION_THREE: doSomeStuff3(); break; // EXIT the switch } Now all you know that break statements are required, because the switch will continue to the next case when break statement is missing. We have an example of that with OPTION_LIKE_ONE, OPTION_ONE_SIMILAR and OPTION_TWO_WITH_PRE_ACTION. The problem is that we only need this "skip to next case" very very very rarely. And very often we put break at the end of case. It very easy for a beginner to forget about it. And one of my C teachers even explained it to us as if it was a bug in C language (don't want to talk about it :) I would like to ask if there are any other languages that I don't know of (or forgot about) that handle switch/case like this: switch (someValue) { case OPTION_ONE: continue; // CONTINUE to next case case OPTION_LIKE_ONE: continue; // CONTINUE to next case case OPTION_ONE_SIMILAR: doSomeStuff1(); // the default is to EXIT the switch case OPTION_TWO_WITH_PRE_ACTION: doPreActionStuff2(); continue; // CONTINUE to next case case OPTION_TWO: doSomeStuff2(); // the default is to EXIT the switch case OPTION_THREE: doSomeStuff3(); // the default is to EXIT the switch } The second question: is there any historical meaning to why it is like this in C? May be continue to next case was used far more often than we use it these days ?

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• Building a survey to put in a WordPress website using Python/Django

  - by chiurox

  So I've been given a task to build a survey to get data regarding time slot preferences of prospective students for a particular course. I know there are really quick solutions to this like Google Forms, SurveyMonkey, but since it's not unusually hard, I want to implement the survey myself in a totally new language as an opportunity to get started with it and also be able to customize and provide dynamic info to the users who are voting. Although I have done some stuff in PHP, C++, javascript, etc, I'm pretty new to Python+Django framework but it's something I've been meaning to get into since a long time ago. Initially, what I want is to make a grid with the days of the week as columns and time-durations as rows. In each cell I want to provide users a way to choose how strong (high/medium/low) their preference for this particular day+time is. I also want to show how many "votes" have already been cast for this particular preference because this will influence a lot in their decisions and as a result make this process easier when we are going to define the classes. I'll probably store the data in MySQL. Could anyone point me to some really good Python+Django tutorials for my particular purpose? Does anyone think I'm wasting my time with this trivial task by choosing new tools and that I should just use something I already know (like PHP) or a free service or plugin for Wordpress? Thanks!

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• Django Many-to-Many Question

  - by DZ

  My questions seems like a common problem that when I have seen any questions on it is never really asked right or not answered. So Im going to try to get the question right, and maybe someone knows how to resolve the issue, or correct my understanding. The problem: When you have a many-to-many relation ship (related_name not through) and you are trying to use the admin interface you are required to input one of the rleationships even though it does not have to exsist for you to create the first entry. Meaning you have to assign a group to an event to create the group. Wow that sounds complicated. So I can see why the question is not getting answered. Lets try the non code explanation example... First and important versions: Django 1.1.1 Phython 2.6 So I have a model where I created a many-to-many realtionship and Im using the related_name Im creating an app that is an event organizer, for simplicty lets say events although they could be anytype). For this first post Im going to stay away from the code and just try to explain. A few keys: (explaining comment) ** - many-to-many So in the model we have 1) The Main Event (this is main model) 2) Groups (link to events and their can be many events for a group) a) Events** I have simplified this example a little becuase I recognize that what does it matter. Just create the event first... But there are specific varations where that will not work. What the many-to-many related_name does it created another table with the indecies of the two other tables. Nothing says that this extra table HAS to be populated. Becuase if I look in the database and work within myPHPadmin I can create a group with out registering an event, since the connection between the two is a seperate table the DB does not care. How do I make the admin interface this realize it? Ok I know thats a lot so I hope I have explained it clearly. Thank you anyone for your comments/thoughts/advice

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• How to build a dynamic resize-able Flash player

  - by Leon

  Morning stackers! So my question today isn't dealing with any code, but how to go about this the correct way from the start. I have a video player built to a static size (max: 800x600) which I'll have to re-code every time I need it to be a different size. What I need it to do in the near future is dynamically resize itself and all the elements inside of it based on 1 width variable that it will received either from HTML or XML. Now to me there are 2 ways to go about this: Start with the smallest size possible and resize upwards, but I'm unsure of how the Flash movie will actually expand upwards as of right now. Or 2, start with the largest size possible (in this case 800x600) and size everything down. Step 1, I think seems to be the better way to go about this (ala YouTube style), but Step 2 also seems like it could be the easier way? A friend of mine mentioned that I should go with the larger size and have elements resize in each class, then fix to the upper left hand corner. However for the player to fit inside of certain div columns on sites, blogs whatever he said that there will have to be an HTML/CSS side of this... meaning that the div containing the resized flash player will have to cover up the areas of the Flash movie that are not to be shown? Is that possible to put a 800x600 flash movie into a div that smaller then 800 pixels wide? And cover it up with another div? Anyways, my mission is to be able to have a dynamically sized player like this: Thoughts? Recommendations? Best practices for this before I start?

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• MATLAB: svds() not converging

  - by Paul

  So using MATLAB's svds() function on some input data as such: [U, S, V, flag] = svds(data, nSVDs, 'L') I noticed that from run to run with the same data, I'd get drastically different output SVD sizes from run to run. When I checked whether 'flag' was set, I found that it was, indicating that the SVDs had not converged. My normal system here would be that if it really needs to converge, I'd do something like this: flag = 1 svdOpts = struct('tol', 1e-10, 'maxit', 600, 'disp', 0); while flag: if svdOpts.maxit > 1e6 error('There''s a real problem here.') end [U, S, V, flag] = svds(data, nSVDs, 'L', svdOpts) svdOpts.maxit = svdOpts.maxit*2 end But from what I can tell, when you use 'L' as the third argument, the fourth argument is ignored, meaning I just have to deal with the fact that it's not converging? I'm not even really sure how to use the 'sigma' argument in place of the 'L' argument. I've also tried reducing the number of SVDs calculated to no avail. Any help on this matter would be much appreciated. EDIT While following up on the comments below, I found that the problem had to do with the way I was building my data matrices. Turned out I had accidentally inverted a matrix and had an input of size (4000x1) rather than (20x200), which was what was refusing to converge. I also did some more timing tets and found that the fourth argument was not, in fact, being ignored, so that's on me. Thanks for the help guys.

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• Create a model that switches between two different states using Temporal Logic?

  - by NLed

  Im trying to design a model that can manage different requests for different water sources. Platform : MAC OSX, using latest Python with TuLip module installed. For example, Definitions : Two water sources : w1 and w2 3 different requests : r1,r2,and r3 - Specifications : Water 1 (w1) is preferred, but w2 will be used if w1 unavailable. Water 2 is only used if w1 is depleted. r1 has the maximum priority. If all entities request simultaneously, r1's supply must not fall below 50%. - The water sources are not discrete but rather continuous, this will increase the difficulty of creating the model. I can do a crude discretization for the water levels but I prefer finding a model for the continuous state first. So how do I start doing that ? Some of my thoughts : Create a matrix W where w1,w2 ? W Create a matrix R where r1,r2,r3 ? R or leave all variables singular without putting them in a matrix I'm not an expert in coding so that's why I need help. Not sure what is the best way to start tackling this problem. I am only interested in the model, or a code sample of how can this be put together. edit Now imagine I do a crude discretization of the water sources to have w1=[0...4] and w2=[0...4] for 0, 25, 50, 75,100 percent respectively. == means implies Usage of water sources : if w1[0]==w2[4] -- meaning if water source 1 has 0%, then use 100% of water source 2 etc if w1[1]==w2[3] if w1[2]==w2[2] if w1[3]==w2[1] if w1[4]==w2[0] r1=r2=r3=[0,1] -- 0 means request OFF and 1 means request ON Now what model can be designed that will give each request 100% water depending on the values of w1 and w2 (w1 and w2 values are uncontrollable so cannot define specific value, but 0...4 is used for simplicity )

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• exit /B 0 does not work...

  - by murxx

  Hi, I have the following problem: I have created a batch script which calls itself in there (for being able to write a log in parallel). In the script I start another process (like start startServer.bat) which starts up a java process and keeps opened up all the time. In my original script I wait 30 seconds, check if the process is running and do an: exit /B 0 Unfortunately that does not work, the window shows that the exit /B 0 is being evaluated, but the window still keeps open. When I close the window with the other process (meaning the "child" processes started up in my .bat) my script continues its run. So: scriptA.bat - in there I call: start startServer.bat - wait 30 seconds - check is server is started - exit /B 0 Process hangs up! What's very odd, if I wrap another script around, like: scriptB.bat - call scriptA.bat ----- in there I call: start startServer.bat ----- wait 30 seconds ----- check is server is started ----- exit /B 0 - scriptA.bat continues without any hangup! I also tried the same with exit 0 (without /B) also, same result! In the first case it hangs up, in the second case my window closes as expected... Has anyone of you ever had such a problem before and knows what's wrong here? Process hangs up!

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• Which options do I have for Java process communication?

  - by Dmitriy Matveev

  We have a place in a code of such form: void processParam(Object param) { wrapperForComplexNativeObject result = jniCallWhichMayCrash(param); processResult(result); } processParam - method which is called with many different arguments. jniCallWhichMayCrash - a native method which is intended to do some complex processing of it's parameter and to create some complex object. It can crash in some cases. wrapperForComplexNativeObject - wrapper type generated by SWIG processResult - a method written in pure Java which processes it's parameter by creation of several kinds (by the kinds I'm not meaning classes, maybe some like hierarchies) of objects: 1 - Some non-unique objects which are referencing each other (from the same hierarchy), these objects can have duplicates created from the invocations of processParam() method with different parameter values. Since it's costly to keep all the duplicates it's necessary to cache them. 2 - Some unique objects which are referencing each other (from the same hierarchy) and some of the objects of 1st kind. After processParam is executed for each of the arguments from some set the data created in processResult will be processed together. The problem is in fact that jniCallWhichMayCrash method may crash the entire JVM and this will be very bad. The reason of crash may be such that it can happen for one argument value and not for the other. We've decided that it's better to ignore crashes inside of JVM and just skip some chunks of data when such crashes occur. In order to do this we should run processParam function inside of separate process and pass the result somehow (HOW? HOW?! This is a question) to the main process and in case of any crashes we will only lose some part of data (It's ok) without lose of everything else. So for now the main problem is implementation of transport between different processes. Which options do I have? I can think about serialization and transmitting of binary data by the streams, but serialization may be not very fast due to object complexity. Maybe I have some other options of implementing this?

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• Objective-C Objects Having Each Other as Properties

  - by mwt

  Let's say we have two objects. Furthermore, let's assume that they really have no reason to exist without each other. So we aren't too worried about re-usability. Is there anything wrong with them "knowing about" each other? Meaning, can each one have the other as a property? Is it OK to do something like this in a mythical third class: Foo *f = [[Foo alloc] init]; self.foo = f; [f release]; Bar *b = [[Bar alloc] init]; self.bar = b; [b release]; foo.bar = bar; bar.foo = foo; ...so that they can then call methods on each other? Instead of doing this, I'm usually using messaging, etc., but sometimes this seems like it might be a tidier solution. I hardly ever see it in example code (maybe never), so I've shied away from doing it. Can somebody set me straight on this? Thanks.

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• Rails: Obfuscating Image URLs on Amazon S3? (security concern)

  - by neezer

  To make a long explanation short, suffice it to say that my Rails app allows users to upload images to the app that they will want to keep in the app (meaning, no hotlinking). So I'm trying to come up with a way to obfuscate the image URLs so that the address of the image depends on whether or not that user is logged in to the site, so if anyone tried hotlinking to the image, they would get a 401 access denied error. I was thinking that if I could route the request through a controller, I could re-use a lot of the authorization I've already built into my app, but I'm stuck there. What I'd like is for my images to be accessible through a URL to one of my controllers, like: http://railsapp.com/images/obfuscated?member_id=1234&pic_id=7890 If the user where to right-click on the image displayed on the website and select "Copy Address", then past it in, it would be the SAME url (as in, wouldn't betray where the image is actually hosted). The actual image would be living on a URL like this: http://s3.amazonaws.com/s3username/assets/member_id/pic_id.extension Is this possible to accomplish? Perhaps using Rails' render method? Or something else? I know it's possible for PHP to return the correct headers to make the browser think it's an image, but I don't know how to do this in Rails... UPDATE: I want all users of the app to be able to view the images if and ONLY if they are currently logged on to the site. If the user does not have a currently active session on the site, accessing the images directly should yield a generic image, or an error message.

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• Extended slice that goes to beginning of sequence with negative stride

  - by recursive

  Bear with me while I explain my question. Skip down to the bold heading if you already understand extended slice list indexing. In python, you can index lists using slice notation. Here's an example: >>> A = list(range(10)) >>> A[0:5] [0, 1, 2, 3, 4] You can also include a stride, which acts like a "step": >>> A[0:5:2] [0, 2, 4] The stride is also allowed to be negative, meaning the elements are retrieved in reverse order: >>> A[5:0:-1] [5, 4, 3, 2, 1] But wait! I wanted to see [4, 3, 2, 1, 0]. Oh, I see, I need to decrement the start and end indices: >>> A[4:-1:-1] [] What happened? It's interpreting -1 as being at the end of the array, not the beginning. I know you can achieve this as follows: >>> A[4::-1] [4, 3, 2, 1, 0] But you can't use this in all cases. For example, in a method that's been passed indices. My question is: Is there any good pythonic way of using extended slices with negative strides and explicit start and end indices that include the first element of a sequence? This is what I've come up with so far, but it seems unsatisfying. >>> A[0:5][::-1] [4, 3, 2, 1, 0]

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• In Java, is there a performance gain in using interfaces for complex models?

  - by Gnoupi

  The title is hardly understandable, but I'm not sure how to summarize that another way. Any edit to clarify is welcome. I have been told, and recommended to use interfaces to improve performances, even in a case which doesn't especially call for the regular "interface" role. In this case, the objects are big models (in a MVC meaning), with many methods and fields. The "good use" that has been recommended to me is to create an interface, with its unique implementation. There won't be any other class implementing this interface, for sure. I have been told that this is better to do so, because it "exposes less" (or something close) to the other classes which will use methods from this class, as these objects are referring to the object from its interface (all public methods from the implementation being reproduced in the interface). This seems quite strange to me, as it seems like a C++ use to me (with header files). There I see the point, but in Java? Is there really a point in making an interface for such unique implementation? I would really appreciate some clarifications on the topic, so I could justify not following such kind of behavior, and the hassle it creates from duplicating all declarations. Edit: Plenty of valid points in most answers, I'm wondering if I won't switch this question for a community wiki, so we can regroup these points in more structured answers.

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• local vs core contoller

  - by latvian

  Hi, I am adding new column and action in the local admin app/code/local/Mage/Adminhtml/Block/Catalog/Product/Grid.php which works fine, however. The local controller/app/code/local/Mage/Adminhtml/Block/Catalog/Product.php is not being used or is not overloading the admin one /app/code/core/Mage/Adminhtml/Block/Catalog/Product.php. This is almost fresh install of Magento 1.4.0.1. I am the only one working, so i know it is not overloaded by some custom controller. I have disabled all custom modules. I have rolled back most of my changes. I have checked /etc/Modules/Mage_Catalog.xml. Refreshed cache all possible ways, loged in and out. Nothing....still using the core contoller copy. why? How do you troubleshoot, meaning, at what moment magento decides using between core or local copies? ...its even more strange because it does not parse local Adminhtml config.xml but uses local Adminthml copy of Blocks. Any pointer would help. I would like to keep everything in local code. Thank You, Margots

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