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• Any ideas for developing a Risc Processor friendly string allocator?

  - by Richard Fabian

  I'm working on some tools to enable high throughput data-oriented development, and one thing that I've not got an immediate answer for is how you go about allocating strings quickly. On risc processors you've got another problem of implementation that the CPU doesn't like branching, which is what I'm trying to minimise or avoid. Also, cache coherence is important on most CPUs, so that's gotta be influential in the design too. So, how would you go about reducing the overhead for a generic string allocator? Sometimes it's easier to solve a more explicit problem, so any ideas for string sizes of 5-30?

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• Avoiding string copying in Lua

  - by Matt Sheppard

  Say I have a C program which wants to call a very simple Lua function with two strings (let's say two comma separated lists, returning true if the lists intersect at all, false if not). The obvious way to do this is to push them onto the stack with lua_pushstring, which works fine, however, from the doc it looks like lua_pushstring but makes a copy of the string for Lua to work with. That means that to cross over to the Lua function is going to require two string copies which I could avoid by rewriting the Lua function in C. Is there any way to arrange things so that the existing C strings could be reused on the Lua side for the sake of performance (or would the strcpy cost pale into insignificance anyway)? From my investigation so far (my first couple of hours looking seriously at Lua), lite userdata seems like the sort of thing I want, but in the form of a string.

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• Python: Hack to call a method on an object that isn't of its class

  - by cool-RR

  Assume you define a class, which has a method which does some complicated processing: class A(object): def my_method(self): # Some complicated processing is done here return self And now you want to use that method on some object from another class entirely. Like, you want to do A.my_method(7). This is what you'd get: TypeError: unbound method my_method() must be called with A instance as first argument (got int instance instead). Now, is there any possibility to hack things so you could call that method on 7? I'd want to avoid moving the function or rewriting it. (Note that the method's logic does depend on self.) One note: I know that some people will want to say, "You're doing it wrong! You're abusing Python! You shouldn't do it!" So yes, I know, this is a terrible terrible thing I want to do. I'm asking if someone knows how to do it, not how to preach to me that I shouldn't do it.

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• mySQL query : working with INTERVAL and CURDATE

  - by Tristan

  Hello, i'm building a chart and i want to recieve data for each months Here's my first request which is working : SELECT s.GSP_nom AS nom, timestamp, AVG( v.vote + v.prix ) /2 AS avg FROM votes_serveur AS v INNER JOIN serveur AS s ON v.idServ = s.idServ WHERE s.valide =1 AND v.date > CURDATE() -30 GROUP BY s.GSP_nom ORDER BY avg DESC But, in my case i've to write 12 request to recieve datas for the 12 previous months, is there any trick to avoid writing : // example for the previous month AND v.date > CURDATE() -60 AND v.date < CURDATE () -30 I heard about INTERVAL, i went to the mySQL doc but i didn't manage to implement it. Any ideas / example of using INTERVAL please ? Thank you

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• Best approach to create a security environment in Java

  - by Tom Brito

  I need to create a desktop application that will run third party code, and I need to avoid the third party code from export by any way (web, clipboard, file io) informations from the application. Somethig like: public class MyClass { private String protectedData; public void doThirdPartyTask() { String unprotedtedData = unprotect(protectedData); ThirdPartyClass.doTask(unprotectedData); } private String unprotect(String data) { // ... } } class ThirdPartyClass { public static void doTask(String unprotectedData) { // Do task using unprotected data. // Malicious code may try to externalize the data. } } I'm reading about SecurityManager and AccessControler, but I'm still not sure what's the best approach to handle this. What should I read about to do this implementation?

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• How to load images and fragments dynamically in LiveCycle Designer forms?

  - by John

  Hi there. I've created a couple of shared templates (.xdp) which will be shared among several clients. Obviously, each client has their own logo and I'd like to set the logo upon form generation. I've managed to change the logo dynamically although I'm not sure if my approach is good. In the xml datasource I've got this element: <ClientID>SomeNumber</ClientId> In the form itself I set the image href with this javascript code: SomeHiddenTextField::calculate HeaderLogo.value.image.href = $record.ClientID + "_logo.jpg"; I've got the logos stored on the server in the same folder as the shared templates. Is this an alright approach to load logos dynamically? I've been trying to achieve the same dynamic behaviour with each client's footer fragment, but I have been unable to figure out how to load these on demand. I could make each footer fragment in to an image but I'd like to avoid it if possible.

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• How do polymorphic inline caches work with mutable types?

  - by kingkilr

  A polymorphic inline cache works by caching the actual method by the type of the object, in order to avoid the expensive lookup procedures (usually a hashtable lookup). How does one handle the type comparison if the type objects are mutable (i.e. the method might be monkey patched into something different at run time). The one idea I've come up with would be a "class counter" that gets incremented each time a method is adjusted, however this seems like it would be exceptionally expensive in a heavily monkey patched environ since it would kill all the PICs for that class, even if the methods for them weren't altered. I'm sure there must be a good solution to this, as this issue is directly applicable to Javascript and AFAIK all 3 of the big JS VMs have PICs (wow acronym ahoy).

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• Require Integer Value not Memory Address whilst avoiding Invalid receiver type compiler warning

  - by Dave Anderson

  I have the following code; int days = [[SettingsUtils daysToRetainHistory] intValue]; [retainHistory setText:[NSString stringWithFormat:@"Days to retain History: %d", days]]; [daysToRetainHistory setValue:days animated:NO]; where [SettingsUtils daysToRetainHistory] is as follows; + (int) daysToRetainHistory { return (int)[[NSUserDefaults standardUserDefaults] objectForKey:@"CaseBaseDaysToRetainHistory"]; } I get the compiler warning Invalid receiver type 'int' because I call intValue on an int but unless I do this I can't seem to get the integer value out and always end up with the memory address i.e. 98765432 instead of 9 which ruins the UILabel display [retainHistory] and the UISlider [daysToRetainHistory] value. How do I avoid the compiler warning and still get my integer value in the label and the necessary float value for setting the UISlider value?

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• Looking for a real-time IMAP notification of new Emails

  - by Emil

  I'm looking for a way to monitor a GMail inbox for new e-mails. However, I want to avoid checking every few minutes and I'm looking for some sort of real-time notification. I've noticed that Outlook (and other IMAP-supporting clients) instantly show when there is a new e-mail, but unfortunately all .NET IMAP libraries seem to lack this functionality. Does anyone know of an IMAP library that has this functionality? Or is there another way to be instantly notified of new message without doing some short-period polling?

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• Recreating "presentModalViewController"?

  - by Benjohn Barnes

  I'm using a UIImagePickerController set up as a camera with an overlay view. I want to present a modal view controller on top on this. When I do so, though, the camera view "closes". This would be okay, but when I dismissModalViewControllerAnimated, I see the closed camera, and there is a long and annoying delay before it reopens. I would like to avoid this. Unless someone has a better approach, I am planning to simply perform the transition that presentModalViewController would perform myself. However, if I take my modal view from it's controller and add it as a sub view of the camera overlay view, like this: [[_imagePickerController cameraOverlayView] addSubview: [viewController view]]; then the modal view doesn't show up at all, and the application crashes with an EXC_BAD_ACCESS in my "modal" view's layoutSubViews. Where as, if I present it with presentModalViewController, everything works fine. Clearly, presentModalViewController is also doing some other stuff. Does anyone know what this is so that I can recreate it?

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• [PHP] Using cURL to download large XML files

  - by ndg

  I'm working with PHP and need to parse a number of fairly large XML files (50-75MB uncompressed). The issue, however, is that these XML files are stored remotely and will need to be downloaded before I can parse them. Having thought about the issue, I think using a system() call in PHP in order to initiate a cURL transfer is probably the best way to avoid timeouts and PHP memory limits. Has anyone done anything like this before? Specifically, what should I pass to cURL to download the remote file and ensure it's saved to a local folder of my choice?

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• How to handle model state errors in ajax-invoked controller action that returns a PartialView

  - by Robert Koritnik

  I have a POST controller action that returns a partial view. Everything seems really easy. but. I load it using $.ajax(), setting type as html. But when my model validation fails I thought I should just throw an error with model state errors. But my reply always returns 500 Server error. How can I report back model state errors without returning Json with whatever result. I would still like to return partial view that I can directly append to some HTML element. Edit I would also like to avoid returning error partial view. This would look like a success on the client. Having the client parse the result to see whether it's an actual success is prone to errors. Designers may change the partial view output and this alone would break the functionality. So I want to throw an exception, but with the correct error message returned to the ajax client.

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• Position elements without overlap

  - by eWolf

  I have a number of rectangular elements that I want to position in a 2D space. I calculate an ideal position for each element. Now my problem is that many elements overlap as very often the ideal positions are concentrated in one region. I want to avoid overlap as much as possible (doesn't have to be perfect, though). How can I do this? I've heard physics simulations are suitable for this - is that correct? And can anyone provide an example/tutorial? By the way: I'm using XNA, if you know any .NET library that does exactly this job - tell me!

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• Is it a solvable problem to generate a regular expression that matches some input set?

  - by Roman

  I provide some input set which contains known separated number of text blocks. I want to make a program that automatically generate 1 or more regular expressions each of which matches every text block in the input set. I see some relatively easy ways to implement a brute-force search. But I'm not an expert in compilers theory. That's why I'm curious: 1) is this problem solvable? or there are some principle impossibility to make such algorithm? 2) is it possible to achieve polynomial complexity for this algorithm and avoid brute forcing?

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• XmlTextWriter.WriteFullEndElement tags on the same line

  - by Apeksha

  I am using an XMLTextWriter to create an XML document dynamically (in VB.Net). I want empty tags to appear like this - <Tag></Tag> and not this - <Tag /> So, I am using WriteFullEndElement to end the element tag. But it is writing out the tag as - <Tag> </Tag> i.e. with a newline character between the tags. The web service reading this XML rejects it due to the newline character. How do I avoid the newline, and have both the start and end tags on the same line?

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• How to expose an entity via alternate keys with spring data rest

  - by dan carter

  Spring-data-rest does a great job exposing entities via their primary key for GET, PUT and DELETE etc. operations. /myentityies/123 It also exposes search operations. /myentities/search/byMyOtherKey?myOtherKey=123 In my case the entities have a number of alternate keys. The systems calling us, will know the objects by these IDs, rather than our internal primary key. Is it possible to expose the objects via another URL and have the GET, PUT and DELETE handled by the built-in spring-data-rest controllers? /myentities/myotherkey/456 We'd like to avoid forcing the calling systems to have to make two requests for each update. I've tried playing with @RestResource path value, but there doesn't seem to be a way to add additional paths.

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• Why is my onSharedPreferenceChangeListener being called multiple times when I change a pref.

  - by brockoli

  I've written an app with 3 tabs. Each tab has the same list view with different data sources. I have setup SharedPreferences in the tabhost activity, but I put my onSharedPreferenceChangeListener method in my listactivity. When I change a preference, my listener gets called and it updates my database. This is all working. However, if I change the data in tab 1, it calls my listener once. If I change the data for tab 2 it calls it twice and if I change the data in tab 3 it calls it three times. Any idea why it works this way? I guess I could setup my shared prefs in my listactivity and that might avoid the issue, but I'm curious why my listener is called multiple times if it's in a different tab. brockoli

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• Limit scope of #define

  - by Ujjwal Singh

  What is the correct strategy to limit the scope of #define and avoid unwarrented token collisions. In the following configuration: Main.c # include "Utility_1.h" # include "Utility_2.h" VOID Utility() // Was written without knowing of: Utility_1 & Utility_2 { const UINT ZERO = 0; } VOID Main() { ... } // Collision; for Line:5 Compiler does not indicate what replaced Utility_1.h # define ZERO "Zero" # define ONE "One" BOOL Utility_1(); Utility_2.h # define ZERO '0' # define ONE '1' BOOL Utility_2(); Utility_2.c # include "Utility_2.h" BOOL Utility_2() { // Using: ZERO & ONE } //Collision: Character Literal replaced with String {Edit} Note: This is supposed to be a generic quesition so do not limit yourself to enum or other defined types. i.e. What to do when: I MUST USE #define Please comment on my proposed solution below.. _

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• What is the best way to clear the CSS style "float"?

  - by Sam Saffron

  I'm pretty accustomed to clearing my floats by using <br style="clear:both"/> but stuff keeps on changing and I am not sure if this is the best practice. There is a CSS hack (from positioneverything) available that lets you achieve the same result without the clearing div. But... they claim the hack is a little out of date and instead you perhaps should look at this hack. But.. after reading through 700 pages of comments :) it seems there may be some places the latter hack does not work. I would like to avoid any javascript hacks cause I would like my clearing to work regardless of javascript being enabled. What is the current best practice for clearing divs in a browser independent way?

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• Prevent my program from being flagged as malware

  - by user120242

  I know that this kind of behavior should be avoided in a publicly deployed program, but it's necessary. I do some hooking of process creation and file/registry I/O, and unpacking. I still trip a heuristic here and there, and I'm worried about future detections. Could I just contact as many AV vendors as I can, submit my program, and provide a link to my program being served publicly? Would it be possible to convince AV vendors to "whitelist" it? Does anyone perhaps have a list of places to submit false positives? Another problem I have is with people who don't update their malware scanners. There seems to be many people who just have old malware defintions and never bother to update. Is there anything that can be done about this? Or, if not, a way to check older definitions so I can locate what is being tripped, so I can try to avoid using that code?

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• Setting the Cursor Position in a Win32 Console Application

  - by Jim Fell

  How can I set the cursor position in a Win32 Console application? Preferably, I would like to avoid making a handle and using the Windows Console Functions. (I spent all morning running down that dark alley; it creates more problems than it solves.) I seem to recall doing this relatively simply when I was in college using stdio, but I can't find any examples of how to do it now. Any thoughts or suggestions would be greatly appreciated. Thanks.

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• How to make WPF app work as a child process in Citrix

  - by RichardOD

  I am working on a 3rd party application that allows plugins to be written in .NET 1.1. I have decided I would like to write my plugin in a seperate process that is called from the .NET 1.1 application (achieved using Process.Start). This is fine- I create a new process that is a WPF app. When I launch this through MSTSC everything works as expected, however when I run the app through Citrix, the WPF child app fails to render correctly, and the mouse position starts going crazy- the child process window is basically not usable. Is there a way to avoid this happening? If I create a seperate WPF application and deploy this through Citrix everything works fine. If I create a child Windows forms app in .NET 3.5, that also works fine.

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• Inserting records in Mysql with INSERT IGNORE and NULL values

  - by Homer1980ar

  I have a partitioned table InnoDB with several fields. I'm trying to avoid duplicates on insert. Let's say: Field1 int null Field2 int null Field3 int null Field4 int null Field5 int null I have created a UNIQUE index on those fields. I try to insert some records with NULL values and then try to reinsert them with IGNORE feature on MySql. Unfortunately it seems to replicated the records when using NULL values. If I try with zeros instead of NULL cases everything works, but I do need the nulls there. Any idea? Thanks, Leonardo

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• Client-side session timeout redirect in ASP.Net

  - by Mercury821

  I want to build a way to automatically redirect users to Timeout.aspx when their session expires due to inactivity. My application uses forms authentication and relies heavily on update panels within the same aspx page for user interaction, so I don't want to simply redirect after a page-level timer expires. For the same reason, I can't use '<meta http-equiv="refresh"/>' What I want to do is create a simple ajax web service with a method called IsSessionTimedOut(), that simply returns a boolean. I will use a javascript timer to periodically call the method, and if it returns true, then redirect to Timeout.aspx. However, I don't want calling this method to reset the session timeout timer, or the session would never time out because of the service call. Is there a clean way to avoid this catch-22? Hopefully there is an easy solution that has so far eluded me.

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• Locking a file to verify a single execution of a service. How reliable?

  - by Camilo Díaz

  Hello, I am deploying a little service to an UNIX(AIX) system. I want to check if there is no active instance of that service running when starting it. How reliable is to implement that check like this? Try to acquire a lock on a file (w/ FileChannel) If succeeds, keep lock and continue execution If fails, exit and refuse to run the main body I am aware of software like the Tanuki wrapper, however, I'm longing for a simpler(maybe not portable) solution. Regarding PIDFILE(s): I want to avoid using them if possible, as I don't have administrative rights on the machine, neither knowledge in AIX's shell programming.

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