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  • Dealing with big IF statements in PHP

    - by Industrial
    Hi everyone, Is there any good alternative for the plain if statements in PHP? I know about switch, but I'll guess that there's some more refined alternative out there that comes handy when working with really big if statements. Thanks a lot,

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  • Suggest Sphinx index scheme

    - by htf
    Hi. In a MySQL database I have documents of different type: some have text content, meta keys, descriptions, others have code, SKU number, size and brand name and so on. The problem is, I have to search something in all of these documents and then display a single page, where the results will be grouped by the document type, such as help page, blog post, item... It's not clear for me how to implement the Sphinx index: I want to have a single index to speed up queries, but since different docs have different structure - how can I group them? I was thinking about just concatenating them, but it just doesn't feel right.

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  • I want to read a big text file

    - by Rozer
    I want to read a big text file, what i decided to create four threads and read 25% of file by each one. and then join them. but its not more impressive. can any one tell me can i use concurrent programming for the same. as my file structure have some data as name contact compnay policyname policynumber uniqueno and I want to put all data in hashmap at last. thanks

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  • [C++] Parent-Child scheme

    - by rubenvb
    I'm writing a class that holds a pointer to a parent object of the same type (think Qt's QObject system). Each object has one parent, and the parent should not be destroyed when a child is destroyed (obviously). class MyClass { public: MyClass(const MyClass* ptr_parent): parent(parent){}; ~MyClass(){ delete[] a_children; }; private: const MyClass* ptr_parent; // go to MyClass above MyClass* a_children; // go to MyClass below size_t sz_numChildren; // for iterating over a_children } (Excuse my inline coding, it's only for brevity) Will destroying the "Master MyClass" take care of all children? No child should be able to kill it's parent, because I would then have pointers in my main program to destroyed objects, correct? Why might you ask? I need a way to "iterate" through all subdirectories and find all files on a platform independent level. The creation of this tree will be handled by native API's, the rest won't. Is this a good idea to start with? Thanks!

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  • How to assign a numbering scheme to TreeNodes based on position

    - by TChristian
    I have a TreeView control in a Windows Forms application that is displaying my own subclass of TreeNode. I need to display a number along with each node's text indicating its position in the tree, like 1 for the root, 1.1 for its first child, 1.2 for its second child, etc. I'm using C# with .NET 2.0 The best that I can come up with is, after the tree is built, go to each node, recursively find the parent and append the parent's sibling number to the front of the node's text until you reach the root.

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  • How big in bytes is a DataRow

    - by JeffreyABecker
    I have a one-time process (hashing all our user passwords) written using datasets. The performance needs improvement so we've profiled the application and found that increasing the 'batch size' of the update will improve performance. I also know that if I load the entire data set into memory the application will start hitting swap and slow down. The question is: how big is a System.Data.DataRow derived class? I'd like to calculate a batch size which I know won't force the application into swap.

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  • parsing a list and producing a structure of that

    - by qzar
    ;; structure representing homework points ;; nr: number - the number of the homework ;; points: number - the number of points reached (define-struct homework (nr points)) ;; parse-homework: (list of number pairs) -> (list of homework) ;; The procedure takes a list of number pairs and produces a list of homework structures ;; Example: (parse-homework (list (list 1 6) (list 2 7) (list 3 0))) should produce (list (make-homework 1 6) (make-homework 2 7) (make-homework 3 0)) (define (parse-homework homework-entries) (if (and (= (length (first homework-entries) 2))(= (length (parse-homework (rest homework-entries)) 2))) (make-homework (first homework-entries) (parse-homework (rest homework-entries))) (error 'Non-valid-input "entered list is not of length two")) ) (parse-homework (list (list 1 6) (list 2 7) (list 3 0))) This code produces the error length: expects 1 argument, given 2: (list 1 6) 2 I really appreciate every explanation that you can give me to get in in this scheme-stuff... Thank you very much

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  • Rewriting UNIX cal(1)

    - by dharmatech
    Hello, Today I was testing out SRFI 19 and wrote a simple version of the UNIX cal(1) command. Here's a version in R6RS Scheme which runs in Ikarus and Ypsilon. A few example runs. Schemers: How would you write it? Use your favorite implementation. Ruby and Python: I'm guessing that y'all have elegant date and time libraries. I'm sure you can put the Schemers to shame. ;-) Let's see what ya got. I'd also like to see Haskell and golfed versions. Is there a Stack Overflow tag for re-implementations of UNIX commands? :-) Ed

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  • What does this xkcd code do?

    - by cobbal
    On the xkcd site today, the following appeared as a joke in a <script language="scheme"> tag so what does the following code do / represent? (define (eval exp env) (cond ((self-evaluating? exp) exp) ((variable? exp) (lookup-variable-value exp env)) ((quoted? exp) (text-of-quotation exp)) ((assignment? exp) (eval-assignment exp env)) ((definition? exp) (eval-definition exp env)) ((if? exp) (eval-if exp env)) ((lambda? exp) (make-procedure (lambda-parameters exp) (lambda-body exp) env)) ((begin? exp) (eval-sequence (begin-actions exp) env)) ((cond? exp) (eval (cond->if exp) env)) ((application? exp) (apply (eval (operator exp) env) (list-of-values (operands exp) env))) (else (error "Common Lisp or Netscape Navigator 4.0+ Required" exp))))

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  • Too many argumants for function

    - by Stas Kurilin
    I'm starting learning Lisp with Java background. In SICP's exercise there is many tasks where students should create abstract functions with many parameters, like (define (filtered-accumulate combiner null-value term a next b filter)...) in exercise 3.11. In Java (language with safe, static typing discipline) - method with more than 4 arguments usually smells, but in Lisp/Scheme it doesnt, does it? I'm wandering how many arguments do you use in you functions? If you use it in production, do you make such many layers?

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  • How are vector patterns used in syntax-rules?

    - by Jay
    Hi, I have been writing Common Lisp macros, so Scheme's R5Rs macros are a bit unnatural to me. I think I got the idea, except that I don't understand how one would use vector patterns in syntax-rules: (define-syntax mac (syntax-rules () ((mac #(a b c d)) (let () (display a) (newline) (display d) (newline))))) (expand '(mac #(1 2 3 4))) ;; Chicken's expand-full extension shows macroexpansion => (let746 () (display747 1) (newline748) (display747 4) (newline748)) I don't see how I'd use a macro that requires its arguments to be written as a vector: (mac #(1 2 3 4)) => 1 4 Is there some kind of technique that uses those patterns? Thank you!

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  • Why exactly is eval evil?

    - by Jay
    I know that Lisp and Scheme programmers usually say that eval should be avoided unless strictly necessary. I´ve seen the same recommendation for several programming languages, but I´ve not yet seen a list of clear arguments against the use of eval. Where can I find an account of the potential problems of using eval? For example, I know the problems of GOTO in procedural programming (makes programs unreadable and hard to maintain, makes security problems hard to find, etc), but I´ve never seen the arguments against eval. Interestingly, the same arguments against GOTO should be valid against continuations, but I see that Shemers, for example, won´t say that continuations are "evil" -- you should just be careful when using them. They´re much more likely to frown upon code using eval than upon code using continuations (as far as I can see -- I could be wrong).

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  • How to have a dynamic theme color in WPF

    - by Ingó Vals
    In WPF I have a few resource dictionaries and in them styles for my panels and controls in my app. I'm reusing the same colors again and again. I actually have 5 colors and they give my app a good color-scheme. However if I wan't to change the theme I have to go into the RD's and change each and every color there. I would like to somewhere have the colors set but don't know how or where. I tried to put a color tag in one RD but as soon as I referenced it in the same RD Visual Studio crashed. Also the best solution would be that I could have the color as a dynamic setting in the app itself so users could even change it themselves.

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  • Newbie programmer looking for a fun, small project (pref. C++/Python)

    - by Francisco P.
    Hello everyone, I have some experience in Scheme and C++ (read: a semester of each) I know the very basics of Python (used it for physics simulations with the Visual Python module). Can you recommend me some fun and small (i.e. don't take much time) projects on either Python or C++? I have no real preferences, just that it is fun :P Thanks for your time! PS: I've tried projecteuler and python challenge. Euler is good, but more about math than coding, and py challenge just didn't work for me.

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  • Experiences teaching or learning map/reduce/etc before recursion?

    - by Jay
    As far as I can see, the usual (and best in my opinion) order for teaching iterting constructs in functional programming with Scheme is to first teach recursion and maybe later get into things like map, reduce and all SRFI-1 procedures. This is probably, I guess, because with recursion the student has everything that's necessary for iterating (and even re-write all of SRFI-1 if he/she wants to do so). Now I was wondering if the opposite approach has ever been tried: use several procedures from SRFI-1 and only when they are not enough (for example, to approximate a function) use recursion. My guess is that the result would not be good, but I'd like to know about any past experiences with this approach.

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  • Definition of "lisp form"?

    - by josh
    Hi, What exactly the definition of a "Lisp form"? As far as I know, it's "either an atom or a list that has a symbol as its first element". But then, this (in Scheme) would not be a form: ((lambda () 42)) ;; The answer to Life, the Universe and Everything. Because the first element of the list is itself another list. And after it's evaluated it will be a procedure (not a symbol). I can find several different websites and tutorials talking about Lisp forms, but none which gives a complete and detailed definition. Where can I find one?

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  • Writing lambda functions in Scala

    - by user2433237
    I'm aware that you can write anonymous functions in Scala but I'm having trouble trying to convert a piece of code from Scheme. Could anyone help me convert this to Scala? (define apply-env (lambda (env search-sym) (cases environment env (empty-env () (eopl:error 'apply-env "No binding for ~s" search-sym)) (extend-env (var val saved-env) (if (eqv? search-sym var) val (apply-env saved-env search-sym))) (extend-env-rec (p-name b-var p-body saved-env) (if (eqv? search-sym p-name) (proc-val (procedure b-var p-body env)) (apply-env saved-env search-sym)))))) Thanks in advance

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  • Extra line breaks inserted in MrEd text%

    - by Jesse Millikan
    In a DrScheme project, I'm using a MrEd editor-canvas% with text% and inserting a string from a literal in a Scheme file. This results in an extra blank line in the editor for each line of text I'm trying to insert. Is this a Windows vs. Unix linebreak problem? I can't find anything about text% treats line breaks in the documentation. ; Inside a class definition: (define/public (edit-pattern p j b d h) (send input-beat set-value (number->string b)) (send input-dwell set-value (number->string d)) (send hold-beats set-value (number->string h)) (send juggler-t erase) ; Why do these add extra newlines (send juggler-t insert j) (send pattern-t erase) (send pattern-t insert p)) (define juggler-ec (new editor-canvas% [parent this] [line-count 12])) (define juggler-t (new text%)) (send juggler-ec set-editor juggler-t) (define pattern-ec (new editor-canvas% [parent this] [line-count 20])) (define pattern-t (new text%)) (send pattern-ec set-editor pattern-t) ; Lots of other stuff...

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  • To divide the big text into columns.

    - by kalininew
    Problem: There is a big piece of the text: <div class="cont"> <p> Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo. Nemo enim ipsam voluptatem, quia voluptas sit, aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos, qui ratione voluptatem sequi nesciunt, neque porro quisquam est, qui dolorem ipsum, quia dolor sit, amet, </p> <p> consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt, ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit, qui in ea voluptate velit esse, quam nihil molestiae consequatur, vel illum, qui dolorem eum fugiat, quo voluptas nulla pariatur? At vero eos et </p> <p> accusamus et iusto odio dignissimos ducimus, qui blanditiis praesentium voluptatum deleniti atque corrupti, quos dolores et quas molestias excepturi sint, obcaecati cupiditate non provident, similique sunt in culpa, qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio, cumque nihil impedit, quo minus id, quod maxime placeat, </p> <p> facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet, ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat. </p> <p> Sed ut perspiciatis, unde omnis iste natus error sit voluptatem accusantium doloremque laudantium, totam rem aperiam eaque ipsa, quae ab illo inventore veritatis et quasi architecto beatae vitae dicta sunt, explicabo. Nemo enim ipsam voluptatem, quia voluptas sit, aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos, qui ratione voluptatem sequi nesciunt, neque porro quisquam est, qui dolorem ipsum, quia dolor sit, amet, </p> <p> consectetur, adipisci velit, sed quia non numquam eius modi tempora incidunt, ut labore et dolore magnam aliquam quaerat voluptatem. Ut enim ad minima veniam, quis nostrum exercitationem ullam corporis suscipit laboriosam, nisi ut aliquid ex ea commodi consequatur? Quis autem vel eum iure reprehenderit, qui in ea voluptate velit esse, quam nihil molestiae consequatur, vel illum, qui dolorem eum fugiat, quo voluptas nulla pariatur? At vero eos et </p> <p> accusamus et iusto odio dignissimos ducimus, qui blanditiis praesentium voluptatum deleniti atque corrupti, quos dolores et quas molestias excepturi sint, obcaecati cupiditate non provident, similique sunt in culpa, qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio, cumque nihil impedit, quo minus id, quod maxime placeat, </p> <p> facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Temporibus autem quibusdam et aut officiis debitis aut rerum necessitatibus saepe eveniet, ut et voluptates repudiandae sint et molestiae non recusandae. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat. </p> </div> It is necessary: To divide it on two columns. On page it should be divided on two about identical (on height) columns. If it is possible: at change of the sizes of the container of the text, a column should remain identical height. Whether probably to set number "n" - on how many columns to divide the big piece of the text. That is to divide the text into any number of columns. Is available: php, xslt, css, pure javascript (without jQuey). What tool is better for using? As it to make, that the decision was ?ross browser compatible.

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  • Using Image Source with big images in WPF

    - by xyzzer
    I am working on an application that allows users to manipulate multiple images by using ItemsControl. I started running some tests and found that the app has problems displaying some big images - ie. it did not work with the high resolution (21600x10800), 20MB images from http://earthobservatory.nasa.gov/Features/BlueMarble/BlueMarble_monthlies.php, though it displays the 6200x6200, 60MB Hubble telescope image from http://zebu.uoregon.edu/hudf/hudf.jpg just fine. The original solution just specified an Image control with a Source property pointing at a file on a disk (through a binding). With the Blue Marble file - the image would just not show up. Now this could be just a bug hidden somewhere deep in the funky MVVM + XAML implementation - the visual tree displayed by Snoop goes like: Window/Border/AdornerDecorator/ContentPresenter/Grid/Canvas/UserControl/Border/ContentPresenter/Grid/Grid/Grid/Grid/Border/Grid/ContentPresenter/UserControl/UserControl/Border/ContentPresenter/Grid/Grid/Grid/Grid/Viewbox/ContainerVisual/UserControl/Border/ContentPresenter/Grid/Grid/ItemsControl/Border/ItemsPresenter/Canvas/ContentPresenter/Grid/Grid/ContentPresenter/Image... Now debug this! WPF can be crazy like that... Anyway, it turned out that if I create a simple WPF application - the images load just fine. I tried finding out the root cause, but I don't want to spend weeks on it. I figured the right thing to do might be to use a converter to scale the images down - this is what I have done: ImagePath = @"F:\Astronomical\world.200402.3x21600x10800.jpg"; TargetWidth = 2800; TargetHeight = 1866; and <Image> <Image.Source> <MultiBinding Converter="{StaticResource imageResizingConverter}"> <MultiBinding.Bindings> <Binding Path="ImagePath"/> <Binding RelativeSource="{RelativeSource Self}" /> <Binding Path="TargetWidth"/> <Binding Path="TargetHeight"/> </MultiBinding.Bindings> </MultiBinding> </Image.Source> </Image> and public class ImageResizingConverter : MarkupExtension, IMultiValueConverter { public Image TargetImage { get; set; } public string SourcePath { get; set; } public int DecodeWidth { get; set; } public int DecodeHeight { get; set; } public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture) { this.SourcePath = values[0].ToString(); this.TargetImage = (Image)values[1]; this.DecodeWidth = (int)values[2]; this.DecodeHeight = (int)values[3]; return DecodeImage(); } private BitmapImage DecodeImage() { BitmapImage bi = new BitmapImage(); bi.BeginInit(); bi.DecodePixelWidth = (int)DecodeWidth; bi.DecodePixelHeight = (int)DecodeHeight; bi.UriSource = new Uri(SourcePath); bi.EndInit(); return bi; } public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture) { throw new Exception("The method or operation is not implemented."); } public override object ProvideValue(IServiceProvider serviceProvider) { return this; } } Now this works fine, except for one "little" problem. When you just specify a file path in Image.Source - the application actually uses less memory and works faster than if you use BitmapImage.DecodePixelWidth. Plus with Image.Source if you have multiple Image controls that point to the same image - they only use as much memory as if only one image was loaded. With the BitmapImage.DecodePixelWidth solution - each additional Image control uses more memory and each of them uses more than when just specifying Image.Source. Perhaps WPF somehow caches these images in compressed form while if you specify the decoded dimensions - it feels like you get an uncompressed image in memory, plus it takes 6 times the time (perhaps without it the scaling is done on the GPU?), plus it feels like the original high resolution image also gets loaded and takes up space. If I just scale the image down, save it to a temporary file and then use Image.Source to point at the file - it will probably work, but it will be pretty slow and it will require handling cleanup of the temporary file. If I could detect an image that does not get loaded properly - maybe I could only scale it down if I need to, but Image.ImageFailed never gets triggered. Maybe it has something to do with the video memory and this app just using more of it with the deep visual tree, opacity masks etc. Actual question: How can I load big images as quickly as Image.Source option does it, without using more memory for additional copies and additional memory for the scaled down image if I only need them at a certain resolution lower than original? Also, I don't want to keep them in memory if no Image control is using them anymore.

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  • Readdirectorychanges not working with big file

    - by sanky
    i was working with readdirectorychangesW till i encountered an unwanted behavior.below is short reference the way i am using my readdirectorychanges func. The behavior is that in case a big file in GBs is copied to the watched directory i get the notification immediately and thereby i start doing my operation according to the notification i receive ,but the file IO ( copy operation is still pending) and that results in unxpected state. Can anyone please suggest a way to synchronize this operation. I want the copy operation(that gave me notification) to get completed first then i want to do my processing. while(ReadDirectoryChangesW( hDir, pBuffer, nBufSize, FALSE, FILE_NOTIFY_CHANGE_FILE_NAME, &BytesReturned, NULL, NULL )) { pBufferCurrent = pBuffer; while(pBufferCurrent) { switch(pBufferCurrent->Action) { case FILE_ACTION_ADDED: break; default: break; } if (pBufferCurrent->NextEntryOffset) pBufferCurrent = (FILE_NOTIFY_INFORMATION*)(((oef_u8_t*)pBufferCurrent) + pBufferCurrent->NextEntryOffset); else pBufferCurrent = NULL; }

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