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• how useful is Turing completeness? are neural nets turing complete?

  - by Albert

  While reading some papers about the Turing completeness of recurrent neural nets (for example: Turing computability with neural nets, Hava T. Siegelmann and Eduardo D. Sontag, 1991), I got the feeling that the proof which was given there was not really that practical. For example the referenced paper needs a neural network which neuron activity must be of infinity exactness (to reliable represent any rational number). Other proofs need a neural network of infinite size. Clearly, that is not really that practical. But I started to wonder now if it does make sense at all to ask for Turing completeness. By the strict definition, no computer system nowadays is Turing complete because none of them will be able to simulate the infinite tape. Interestingly, programming language specification leaves it most often open if they are turing complete or not. It all boils down to the question if they will always be able to allocate more memory and if the function call stack size is infinite. Most specification don't really specify this. Of course all available implementations are limited here, so all practical implementations of programming languages are not Turing complete. So, what you can say is that all computer systems are just equally powerful as finite state machines and not more. And that brings me to the question: How useful is the term Turing complete at all? And back to neural nets: For any practical implementation of a neural net (including our own brain), they will not be able to represent an infinite number of states, i.e. by the strict definition of Turing completeness, they are not Turing complete. So does the question if neural nets are Turing complete make sense at all? The question if they are as powerful as finite state machines was answered already much earlier (1954 by Minsky, the answer of course: yes) and also seems easier to answer. I.e., at least in theory, that was already the proof that they are as powerful as any computer.

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• Getting my foot in the SCADA door, how?

  - by bibby

  I keep hearing that I should learn SCADA and its PLC language to upgrade my career. While I enjoy currently being a web and mobile development privateer, the prospects of working for a municipality or industrial entity has its appeals (since I am trying to grow a family). Over the years, I've tought myself to skillfully use php, javascript, java, perl, awk, bash. Surely, these language skills can tranfer somewhat to SCADA's logic controller language. Without any formal training in CS (music major!) other than at the workplace, I wouldn't have been able to pick up those languages and run with them had it not been for their open documentation and free-to-install or already-installed interpreters/compilers. I can't see that this is true with SCADA, and I'm hoping that I'm wrong. Ideally, I'd like to be able to apply for a job that requires [A,B,C] and suggest that they hire me because I already know [A & B]; that they wouldn't have to do a ground-up training with someone that's never programmed before. So, finally, the question; How do I "learn" SCADA? Are there sites and docs? What's going to help me get my foot in the door? Any insight is appreciated. Thanks!

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• How can I work around WinXP using ports 1025-5000 as ephemeral?

  - by Chris Dolan

  If you create a TCP client socket with port 0 instead of a non-zero port, then the operating system chooses any free ephemeral port for you. Most OSes choose ephemeral ports from the IANA dynamic port range of 49152-65535. However in Windows Server 2003 and earlier (including XP) Microsoft used ports 1025-5000 as the ephemeral range, according to their bind() documentation. I run multiple Java services on the same hardware. On rare occasions, this range collides with well-known ports that I use for other services (e.g. port 4160 for Jini discovery). While rare, this has caused real problems. Is there any easy way to tell Windows or Java to use a different port range for client sockets? Microsoft's docs indicate that I can change the high end of that range via the MaxUserPort TcpIP registry setting, but I see no way to change the low end. Update: I've made some progress on this. It looks like Microsoft has a concept of reserved ports that are exceptions to the ephemeral port range. There's a registry setting that lets you change this permanently and apparently there must be an API to do the same thing because there's a data structure that holds high/low values for reserved port ranges, but I can't find the actual function call anywhere... The registry solution may work, but now I'm fixated on this API.

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• How to get XML element/attribute name in SQL Server 2005

  - by OG Dude

  Hi, I have a simple procedure in SQL Server 2005 which takes some XML as input. The element attributes correspond to field names in tables. I'd like to be able to determine <elementName>, <attribNameX> dynamically as to avoid having to hardcode them into the procedure. How can I do this? The XML looks like this: <ROOT> <elementName attribName1 = "xxx" attribName2 = "yyy"/> <elementName attribName1 = "aaa" attribName2 = "bbb"/> ... </ROOT> The stored procedure like this: CREATE PROC dbo.myProc ( @XMLInput varchar(1000) ) AS BEGIN SET NOCOUNT ON DECLARE @XMLDocHandle int EXEC sp_xml_preparedocument @XMLDocHandle OUTPUT, @XMLInput SELECT someTable.someCol FROM dbo.someTable JOIN OPENXML (@XMLDocHandle, '/ROOT/elementName',1) WITH (attrib1Name int, attrib2Name int) AS XMLData ON someTable.attribName1 = XMLData.attribName1 AND someTable.attribName2 = XMLData.attribName2 EXEC sp_xml_removedocument @XMLDocHandle END GO The question has been asked here before but maybe there is a cleaner solution. Additionally, I'd like to pass the tablename as a parameter as well - I read some stuff arguing that this is bad style - so what would be a good solution for having a dynamic tablename? Thanks a lot in advance, /David

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• Hide anchors using jQuery

  - by Eric Di Bari

  I've created a dynamic page that, depending on the view type, will sometimes utilize the anchor tags and other times not. Essentially, I want to be able to control if on click the page jumps to the anchor. Is it possible to hide anchor tags using jQUery, so they are essentially removed? I need to be able to re-enable the anchors when necessary, and always show the current anchor in the browser's address bar. It seems to work in FireFox, but not in Internet Explorer. I have three sections: the 'table of contents', the content, and the javascript (jQuery) code Table of Contents <a id="expandLink0" class="expandLinksList" href="#green">What is green purchasing</a><br> <a id="expandLink1" class="expandLinksList" href="#before">Before you buy</a><br> Contents <ul id="makeIntoSlideshowUL">' <li id="slideNumber0" class="slideShowSlide"> <a name="green"></a> <div>Green Purchasing refers to the procurement of products and service...<a href="#topOfPageAnchor" class="topOfPageAnchorClass">Back to Top</a></div> </li> <li id="slideNumber1" class="slideShowSlide"> <a name="before"></a> <div>We easily accomplish the first four bullet points under...<a href="#topOfPageAnchor" class="topOfPageAnchorClass">Back to Top</a></div> </li> </ul> jQuery On Page Load $(".slideShowSlide").each(function() { $(this).children(":first-child").hide(); }); jQuery to re-enable links $(".slideShowSlide").each(function() { $(this).children(":first-child").show(); });

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• Please help us non-C++ developers understand what RAII is

  - by Charlie Flowers

  Another question I thought for sure would have been asked before, but I don't see it in the "Related Questions" list. Could you C++ developers please give us a good description of what RAII is, why it is important, and whether or not it might have any relevance to other languages? I do know a little bit. I believe it stands for "Resource Acquisition is Initialization". However, that name doesn't jive with my (possibly incorrect) understanding of what RAII is: I get the impression that RAII is a way of initializing objects on the stack such that, when those variables go out of scope, the destructors will automatically be called causing the resources to be cleaned up. So why isn't that called "using the stack to trigger cleanup" (UTSTTC:)? How do you get from there to "RAII"? And how can you make something on the stack that will cause the cleanup of something that lives on the heap? Also, are there cases where you can't use RAII? Do you ever find yourself wishing for garbage collection? At least a garbage collector you could use for some objects while letting others be managed? Thanks.

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• How to intercept, parse and compile?

  - by epitka

  This is a problem I've been struggling to solve for a while. I need a way to either replace code in the method with a parsed code from the template at compile time (PostSharp comes to mind) or to create a dynamic proxy (Linfu or Castle). So given a source code like this [Template] private string GetSomething() { var template = [%=Customer.Name%] } I need it to be compiled into this private string GetSomething() { MemoryStream mStream = new MemoryStream(); StreamWriter writer = new StreamWriter(mStream,System.Text.Encoding.UTF8); writer.Write(@"" ); writer.Write(Customer.Name); StreamReader sr = new StreamReader(mStream); writer.Flush(); mStream.Position = 0; return sr.ReadToEnd(); } It is not important what technology is used. I tried with PostSharp's ImplementMethodAspect but got nowhere (due to lack of experience with it). I also looked into Linfu framework. Can somebody suggest some other approach or way to do this, I would really appreciate. My whole project depends on this.

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• What are the alternatives to public fields?

  - by James

  I am programming a game in java, and as the question title suggestions i am using public fields in my classes. (for the time being) From what i have seen public fields are bad and i have some understanding why. (but if someone could clarify why you should not use them, that would be appreciated) The thing is that also from what i have seen, (and it seems logical) is that using private fields, but using getters and setters to access them is also not good as it defeats the point of using private fields in the first place. So, my question is, what are the alternatives? or do i really have to use private fields with getters and setters? For reference here is one of my classes, and some of its methods. I will elaborate more if needs be. //The player's fields. public double health; public String name; public double goldCount; public double maxWeight; public double currentWeight; public double maxBackPckSlts; public double usedBackPckSlts; // The current back pack slots in use public double maxHealth; // Maximum amount of health public ArrayList<String> backPack = new ArrayList<String>(); //This method happens when ever the player dynamically takes damage(i.e. when it is not scripted for the player to take damage. //Parameters will be added to make it dynamic so the player can take any spread of damage. public void beDamaged(double damage) { this.health -= damage; if (this.health < 0) { this.health = 0; } } public void gainHealth(double gainedHp) { this.health += gainedHp; if (this.health > this.maxHealth) { this.health = this.maxHealth; } }

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• Ajax Rich Internet Application framework for Linux + Firefox _AND_ iPhone consumption

  - by Maroloccio

  For a zero-budget (e.g. University) project we need to build a rich web UI for Firefox and iPhone clients. Firm requirement: all technologies to be free and open-source. Nice-to-have: all development to be done in Java/Eclipse. I generally like the Google's AppEngine + GWT combo but this project will require much more interactivity than what's in GWT 2.0. Something along the lines of: http://www.smartclient.com/smartgwt/showcase/. I know trusty plain ol' GWT won't cut it this time. Straight question: is there something that does the sort of thing that SmartGWT does and works really well on Safari/iPhone? I would say the mobile experience is even more important for this project than the desktop one. Optional question: perhaps this is not the best route to go at all? How could we otherwise render a rich UI with such capabilities and interactivity on both screen sizes? Windows, drag-and-drop, advanced tabs, dynamic grids... We don't need to support any other mobile devices. Yet. ;-)

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• Legitimate uses of the Function constructor

  - by Marcel Korpel

  As repeatedly said, it is considered bad practice to use the Function constructor (also see the ECMAScript Language Specification, 5th edition, § 15.3.2.1): new Function ([arg1[, arg2[, … argN]],] functionBody) (where all arguments are strings containing argument names and the last (or only) string contains the function body). To recapitulate, it is said to be slow, as explained by the Opera team: Each time […] the Function constructor is called on a string representing source code, the script engine must start the machinery that converts the source code to executable code. This is usually expensive for performance – easily a hundred times more expensive than a simple function call, for example. (Mark ‘Tarquin’ Wilton-Jones) Though it's not that bad, according to this post on MDC (I didn't test this myself using the current version of Firefox, though). Crockford adds that [t]he quoting conventions of the language make it very difficult to correctly express a function body as a string. In the string form, early error checking cannot be done. […] And it is wasteful of memory because each function requires its own independent implementation. Another difference is that a function defined by a Function constructor does not inherit any scope other than the global scope (which all functions inherit). (MDC) Apart from this, you have to be attentive to avoid injection of malicious code, when you create a new Function using dynamic contents. Lots of disadvantages and it is intelligible that ECMAScript 5 discourages the use of the Function constructor by throwing an exception when using it in strict mode (§ 13.1). That said, T.J. Crowder says in an answer that [t]here's almost never any need for the similar […] new Function(...), either, again except for some advanced edge cases. So, now I am wondering: what are these “advanced edge cases”? Are there legitimate uses of the Function constructor?

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• Truncate portions of a string to limit the whole string's length in Ruby

  - by Horace Loeb

  Suppose you want to generate dynamic page titles that look like this: "It was all a dream, I used to read word up magazine" from "Juicy" by The Notorious B.I.G I.e., "LYRICS" from "SONG_NAME" by ARTIST However, your title can only be 69 characters total and this template will sometimes generate titles that are longer. One strategy for solving this problem is to truncate the entire string to 69 characters. However, a better approach is to truncate the less important parts of the string first. I.e., your algorithm might look something like this: Truncate the lyrics until the entire string is <= 69 characters If you still need to truncate, truncate the artist name until the entire string is <= 69 characters If you still need to truncate, truncate the song name until the entire string is <= 69 characters If all else fails, truncate the entire string to 69 characters Ideally the algorithm would also limit the amount each part of the string could be truncated. E.g., step 1 would really be "Truncate the lyrics to a minimum of 10 characters until the entire string is <= 69 characters" Since this is such a common situation, I was wondering if someone has a library or code snippet that can take care of it.

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• Culture Sensitive GetHashCode

  - by user114928

  Hi, I'm writing a c# application that will process some text and provide basic query functions. In order to ensure the best possible support for other languages, I am allowing the users of the application to specify the System.Globalization.CultureInfo (via the "en-GB" style code) and also the full range of collation options using the System.Globalization.CompareOptions flags enum. For regular string comparison I'm then using a combination of: a) String.Compare overload that accepts the culture and options b) For some bulk processes I'm caching the byte data (KeyData) from CompareInfo.GetSortKey (overload that accepts the options) and using a byte-by-byte comparison of the KeyData. This seemed fine (although please comment if you think these two methods shouldn't be mixed), but then I had reason to use the HashSet< class which only has an overload for IEqualityComparer<. MS documentation seems to suggest that I should use StringComparer (which implements both IEqualityComparer< and IComparer<), but this only seems to support the "IgnoreCase" option from CompareOptions and not "IgnoreKanaType", "IgnoreSymbols", "IgnoreWidth" etc. I'm assuming that a StringComparer that ignores these other options could produce different hashcodes for two strings that might be considered the same using my other comparison options. I'd therefore get incorrect results from my application. Only thought at the moment is to create my own IEqualityComparer< that generates a hashcode from the SortKey.KeyData and compares eqality be using the String.Compare overload. Any suggestions?

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• Automatic testing of GUI related private methods

  - by Stein G. Strindhaug

  When it comes to GUI programming (at least for web) I feel that often the only thing that would be useful to unit test is some of the private methods*. While unit testing makes perfect sense for back-end code, I feel it doesn't quite fit the GUI classes. What is the best way to add automatic testing of these? * Why I think the only methods useful to test is private: Often when I write GUI classes they don't even have any public methods except for the constructor. The public methods if any is trivial, and the constructor does most of the job calling private methods. They receive some data from server does a lot of trivial output and feeds data to the constructor of other classes contained inside it, adding listeners that calls a (more or less directly) calls the server... Most of it pretty trivial (the hardest part is the layout: css, IE, etc.) but sometimes I create some private method that does some advanced tricks, which I definitely do not want to be publicly visible (because it's closely coupled to the implementation of the layout, and likely to change), but is sufficiently complicated to break. These are often only called by the constructor or repeatedly by events in the code, not by any public methods at all. I'd like to have a way to test this type of methods, without making it public or resorting to reflection trickery. (BTW: I'm currently using GWT, but I feel this applies to most languages/frameworks I've used when coding for GUI)

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• Problems importing WAR files in Eclipse?

  - by CitadelCSAlum

  I was unfortunately forced to result to uploading a WAR file as my backup for a web application I am working on. Luckily I have the most recent WAR file available. I am using Eclipse IDE and am using the Web Tools plugin for all the J2EE work that I am doing with the Dynamic Web Application Project. When I imported my WAR file, and ran it on a local server, everything works fine. The problem I a ran into is that in the Java Resources/src folder that all my packages and .java files were now only consists of all the same packages, but they are empty. I checked to see if I could find the files and I found the .class files in an "Imported files" folder that is not accessible in the Eclipse Project Explorer. I believe that I need to do some type of build or something so that my .java files are available for me, but unfortunately this is one area where I lack. One thing I would also like to know is, one way or the other, am I able to obtain the .java source code files if I have access to the .class files? Also, I would like to configure this environment as it was before where my Java Resources:src folder contaiend the packages and .java files.

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• Reading numpy arrays outside of Python

  - by Abiel

  In a recent question I asked about the fastest way to convert a large numpy array to a delimited string. My reason for asking was because I wanted to take that plain text string and transmit it (over HTTP for instance) to clients written in other programming languages. A delimited string of numbers is obviously something that any client program can work with easily. However, it was suggested that because string conversion is slow, it would be faster on the Python side to do base64 encoding on the array and send it as binary. This is indeed faster. My question now is, (1) how can I make sure my encoded numpy array will travel well to clients on different operating systems and different hardware, and (2) how do I decode the binary data on the client side. For (1), my inclination is to do something like the following import numpy as np import base64 x = np.arange(100, dtype=np.float64) base64.b64encode(x.tostring()) Is there anything else I need to do? For (2), I would be happy to have an example in any programming language, where the goal is to take the numpy array of floats and turn them into a similar native data structure. Assume we have already done base64 decoding and have a byte array, and that we also know the numpy dtype, dimensions, and any other metadata which will be needed. Thanks.

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• How to implement custom JSF component for drawing chart?

  - by Roman

  I want to create a component which can be used like: <mc:chart data="#{bean.data}" width="200" height="300" /> where #{bean.data} returns a collection of some objects or chart model object or something else what can be represented as a chart (to put it simple, let's assume it returns a collection of integers). I want this component to generate html like this: <img src="someimg123.png" width="200" height="300"/> The problem is that I have some method which can receive data and return image, like: public RenderedImage getChartImage (Collection<Integer> data) { ... } and I also have a component for drawing dynamic image: <o:dynamicImage width="200" height="300" data="#{bean.readyChartImage}/> This component generates html just as I need but it's parameter is array of bytes or RenderedImage i.e. it needs method in bean like this: public RenderedImage getReadyChartImage () { ... } So, one approach is to use propertyChangedListener on submit to set data (Collection<Integer>) for drawing chart and then use <o:dynamicImage /> component. But I'd like to create my own component which receives data and draws chart. I'm using facelets but it's not so important indeed. Any ideas how to create the desired component? P.S. One solution I was thinking about is not to use <o:dynamicImage/> and use some servlet to stream image. But I don't know how to implement that correctly and how to tie jsf component with servlet and how to save already built chart images (generating new same image for each request can cause performance problems imho) and so on..

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• Finding a MIME type for a file on windows

  - by rmeador

  Is there a way to get a file's MIME type using some system call on Windows? I'm writing an IIS extension in C++, so it must be callable from C++, and I do have access to IIS if there is some functionality exposed. Obviously, IIS itself must be able to do this, but my googling has been unable to find out how. I did find this .net related question here on SO, but that doesn't give me much hope (as neither a good solution nor a C++ solution is mentioned there). I need it so I can serve up dynamic files using the appropriate content type from my app. My plan is to first consult a list of MIME types within my app, then fall back to the system's MIME type listing (however that works; obviously it exists since it's how you associate files with programs). I only have a file extension to work with in some cases, but in other cases I may have an actual on-disk file to examine. Since these will not be user-uploaded files, I believe I can trust the extension and I'd prefer an extension-only lookup solution since it seems simpler and faster. Thanks!

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• Increase width of divs, displayed side by side, using draggable events

  - by Vaibhav Shukla

  I have two divs of fixed length as of now, which loads external URL by dynamically embedding iframes inside them. Divs are appearing next to each other - one on left and other right. As of now, I have fixed their width to 50% each. But, I want to give user a flexibility to increase the width of any div to view the URL inside easily without scrolling horizontally. Something like dragging the border separating the two divs to either left or right according to his need. Is there a way I could achieve this? Please suggest any library or something. I have gone through a library twentytwenty which is used for images. I don't know how will that work for dynamic iframes. Here is the JSFiddle which displays the divs. <div> <div id="originalPage" style="width:54%;height: 730px;float:left"> <p>one div </p> </div> <div id="diffReport" style="width:45%; height: 730px;float:right"> <p>another div</p> </div> </div>

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• Paypal Encrypted Website payments

  - by John Isaacks

  I am trying to integrate a PayPal Website Payments Standard Cart Upload payment type into my shopping cart. I integrated Google Checkout a while back and I did not find it overly confusing as I do paypal. I am getting info on how to encrypt it from here: https://cms.paypal.com/us/cgi-bin/?&cmd=_render-content&content_ID=developer/e_howto_html_encryptedwebpayments#id08A3I0P017Q Paypal says I need to generate a private key and a public certificate using OpenSSL. I went to OpenSSL and downloaded the latest release, which is just a folder containing various files but I see no application I can use, not sure what to do here. Even if I were to get OpenSSL to generate me a private key and public cert, the next step is to download either an MS or Java command line tool to create the encrypted cart ahead of time with the cart-total, tax, etc. which sounds crazy to me, like I am supposed to manually do this prior to every order?? Obviously I do not know the items in the cart the customer is going to buy before hand so I need this to be done on the fly on my website using PHP. But I am completely lost. There has to be a way to setup dynamic secure cart uploads to paypal. Can someone please point me in the right direction?

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• Access cost of dynamically created objects with dynamically allocated members

  - by user343547

  I'm building an application which will have dynamic allocated objects of type A each with a dynamically allocated member (v) similar to the below class class A { int a; int b; int* v; }; where: The memory for v will be allocated in the constructor. v will be allocated once when an object of type A is created and will never need to be resized. The size of v will vary across all instances of A. The application will potentially have a huge number of such objects and mostly need to stream a large number of these objects through the CPU but only need to perform very simple computations on the members variables. Could having v dynamically allocated could mean that an instance of A and its member v are not located together in memory? What tools and techniques can be used to test if this fragmentation is a performance bottleneck? If such fragmentation is a performance issue, are there any techniques that could allow A and v to allocated in a continuous region of memory? Or are there any techniques to aid memory access such as pre-fetching scheme? for example get an object of type A operate on the other member variables whilst pre-fetching v. If the size of v or an acceptable maximum size could be known at compile time would replacing v with a fixed sized array like int v[max_length] lead to better performance? The target platforms are standard desktop machines with x86/AMD64 processors, Windows or Linux OSes and compiled using either GCC or MSVC compilers.

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• Display image background fully for last repeat in a div

  - by Stiggler

  I have a 700x300 background repeating seamlessly under the main content-div. Now I'd like to attach a div at the bottom of the content-div, containing a continuation-to-end of the background image, connecting seamlessly with the background above it. Due to the nature of the pattern, unless the full 300px height of the background image is visible in the last repeat of the content-div's backround, the background in the div below won't seamlessly connect. Basically, I need the content div's height to be a multiple of 300px under all circumstances. What's a good approach to this sort of problem? I've tried resizing the content-div on loading the page, but this only works as long as the content div doesn't contain any resizing, dynamic content, which is not my case: function adjustContentHeight() { // Setting content div's height to nearest upper multiple of column backgrounds height, // forcing it not to be cut-off when repeated. var contentBgHeight = 300; var contentHeight = $("#content").height(); var adjustedHeight = Math.ceil(contentHeight / contentBgHeight); $("#content").height(adjustedHeight * contentBgHeight); } $(document).ready(adjustContentHeight); What I'm looking for there is a way to respond to a div resizing event, but there doesn't seem to be such a thing. Also, please assume I have no access to the JS controlling the resizing of content in the content-div, though this is potentially a way of solving the problem. Another potential solution I was thinking off was to offset the background image in the bottom div by a certain amount depending on the height of the content-div. Again, the missing piece seems to be the ability to respond to a resize event.

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• How to provide js-ctypes in a spidermonkey embedding?

  - by Triston J. Taylor

  Summary I have looked over the code the SpiderMonkey 'shell' application uses to create the ctypes JavaScript object, but I'm a less-than novice C programmer. Due to the varying levels of insanity emitted by modern build systems, I can't seem to track down the code or command that actually links a program with the desired functionality. method.madness This js-ctypes implementation by The Mozilla Devs is an awesome addition. Since its conception, scripting has been primarily used to exert control over more rigorous and robust applications. The advent of js-ctypes to the SpiderMonkey project, enables JavaScript to stand up and be counted as a full fledged object oriented rapid application development language flying high above 'the bar' set by various venerable application development languages such as Microsoft's VB6. Shall we begin? I built SpiderMonkey with this config: ./configure --enable-ctypes --with-system-nspr followed by successful execution of: make && make install The js shell works fine and a global ctypes javascript object was verified operational in that shell. Working with code taken from the first source listing at How to embed the JavaScript Engine -MDN, I made an attempt to instantiate the JavaScript ctypes object by inserting the following code at line 66: /* Populate the global object with the ctypes object. */ if (!JS_InitCTypesClass(cx, global)) return NULL; /* I compiled with: g++ $(./js-config --cflags --libs) hello.cpp -o hello It compiles with a few warnings: hello.cpp: In function ‘int main(int, const char**)’: hello.cpp:69:16: warning: converting to non-pointer type ‘int’ from NULL [-Wconversion-null] hello.cpp:80:20: warning: deprecated conversion from string constant to ‘char*’ [-Wwrite-strings] hello.cpp:89:17: warning: NULL used in arithmetic [-Wpointer-arith] But when you run the application: ./hello: symbol lookup error: ./hello: undefined symbol: JS_InitCTypesClass Moreover JS_InitCTypesClass is declared extern in 'dist/include/jsapi.h', but the function resides in 'ctypes/CTypes.cpp' which includes its own header 'CTypes.h' and is compiled at some point by some command during 'make' to yeild './CTypes.o'. As I stated earlier, I am less than a novice with the C code, and I really have no idea what to do here. Please give or give direction to a generic example of making the js-ctypes object functional in an embedding.

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• Given 4 objects, how to figure out whether exactly 2 have a certain property

  - by Cocorico

  Hi guys! I have another question on how to make most elegant solution to this problem, since I cannot afford to go to computer school right so my actual "pure programming" CS knowledge is not perfect or great. This is basically an algorhythm problem (someone please correct me if I am using that wrong, since I don't want to keep saying them and embarass myself) I have 4 objects. Each of them has an species property that can either be a dog, cat, pig or monkey. So a sample situation could be: object1.species=pig object2.species=cat object3.species=pig object4.species=dog Now, if I want to figure out if all 4 are the same species, I know I could just say: if ( (object1.species==object2.species) && (object2.species==object3.species) && (object3.species==object4.species) ) { // They are all the same animal (don't care WHICH animal they are) } But that isn't so elegant right? And if I suddenly want to know if EXACTLY 3 or 2 of them are the same species (don't care WHICH species it is though), suddenly I'm in spaghetti code. I am using Objective C although I don't know if that matters really, since the most elegant solution to this is I assume the same in all languages conceptually? Anyone got good idea? Thanks!!

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• (x86) Assembler Optimization

  - by Pindatjuh

  I'm building a compiler/assembler/linker in Java for the x86-32 (IA32) processor targeting Windows. High-level concepts of a "language" (in essential a Java API for creating executables) are translated into opcodes, which then are wrapped and outputted to a file. The translation process has several phases, one is the translation between languages: the highest-level code is translated into the medium-level code which is then translated into the lowest-level code (probably more than 3 levels). My problem is the following; if I have higher-level code (X and Y) translated to lower-level code (x, y, U and V), then an example of such a translation is, in pseudo-code: x + U(f) // generated by X + V(f) + y // generated by Y (An easy example) where V is the opposite of U (compare with a stack push as U and a pop as V). This needs to be 'optimized' into: x + y (essentially removing the "useless" code) My idea was to use regular expressions. For the above case, it'll be a regular expression looking like this: x:(U(x)+V(x)):null, meaning for all x find U(x) followed by V(x) and replace by null. Imagine more complex regular expressions, for more complex optimizations. This should work on all levels. What do you suggest? What would be a good approach to optimize in these situations?

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• SQL Pivot table error-using variable gives syntax error

  - by Antoni

  Hi my coworker came to me with this error and now I am hooked and trying to figure it out, hope some of the experts can help us! Thanks so much! When I execute Step6 we get this error: Msg 102, Level 15, State 1, Line 4 Incorrect syntax near '@cols'. --Sample of pivot query --Creating Test Table Step1 CREATE TABLE Product(Cust VARCHAR(25), Product VARCHAR(20), QTY INT) GO -- Inserting Data into Table Step2 INSERT INTO Product(Cust, Product, QTY) VALUES('KATE','VEG',2) INSERT INTO Product(Cust, Product, QTY) VALUES('KATE','SODA',6) INSERT INTO Product(Cust, Product, QTY) VALUES('KATE','MILK',1) INSERT INTO Product(Cust, Product, QTY) VALUES('KATE','BEER',12) INSERT INTO Product(Cust, Product, QTY) VALUES('FRED','MILK',3) INSERT INTO Product(Cust, Product, QTY) VALUES('FRED','BEER',24) INSERT INTO Product(Cust, Product, QTY) VALUES('KATE','VEG',3) GO -- Selecting and checking entires in table Step3 SELECT * FROM Product GO -- Pivot Table ordered by PRODUCT Step4 select * FROM ( SELECT * FROM Product) up PIVOT (SUM(QTY) FOR CUST IN ([FRED], [KATE])) AS pvt ORDER BY PRODUCT GO --dynamic pivot???? Step5 DECLARE @cols NVARCHAR(2000) select @cols = STUFF(( SELECT DISTINCT TOP 100 PERCENT '],[' + b.Cust FROM (select top 100 Cust from tblProduct)b ORDER BY '],[' + b.Cust FOR XML PATH('') ), 1, 2, '') + ']' --Show Step6 SELECT * FROM (SELECT * FROM tblProduct) p PIVOT (SUM(QTY) FOR CUST IN (@cols)) as pvt Order by Product

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