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• Using Groovy as a scripting language...

  - by Zombies

  I prefer to use scripting languages for short tasks, anything such as a really simple http bot, bulk importing/exporting data to/from somewhere, etc etc... Basic throw-away scripts and simple stuff. The point being, that a scripting language is just an efficient tool to write quick programs with. As for my understanding of Groovy at this point... If you were to program in Groovy, and you wan't to write a quick script, wouldn't you be forced to going back to regular java syntax (and we know how that can be convoluted compared to a scripting language) in order to do anything more complicated? For example, if I want to do some http scripting, wouldn't I just be right back at using java syntax to invoke Commons HttpClient? To me, the point of a scripting language is for quickly typed and less forced constructs. And here is another thing, it doesn't seem that there is any incentive for groovy based libraries to be developed when there are already so many good java one's out there, thus making groovy appear to be a Java dependent language with minor scripting features. So right now I am wondering if I could switch to Groovy as a scripting language or continue to use a more common scripting language such as Perl, Python or Ruby.

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• Silverlight 4 race condition with DataGrid master details control

  - by Simon_Weaver

  Basically I want a DataGrid (master) and details (textbox), where DataGrid is disabled during edit of details (forcing people to save/cancel)... Here's what I have... I have a DataGrid which serves as my master data. <data:DataGrid IsEnabled="{Binding CanLoad,ElementName=dsReminders}" ItemsSource="{Binding Data, ElementName=dsReminders}" > Its data comes from a DomainDataSource: <riaControls:DomainDataSource Name="dsReminders" AutoLoad="True" ... I have a bound Textbox which is the 'details' (very simple right now). There are buttons (Save/Cancel) which should be enabled when user tries to edit the text. Unfortunately Silverlight doesn't support UpdateSourceTrigger=PropertyChanged so I have to raise an event: <TextBox Text="{Binding SelectedItem.AcknowledgedNote, Mode=TwoWay, UpdateSourceTrigger=Explicit, ElementName=gridReminders}" TextChanged="txtAcknowledgedNote_TextChanged"/> The event to handle this calls BindingExpression.UpdateSource to update the source immediately: private void txtAcknowledgedNote_TextChanged(object sender, TextChangedEventArgs e) { BindingExpression be = txtAcknowledgedNote.GetBindingExpression(TextBox.TextProperty); be.UpdateSource(); } IN other words - typing in the textbox causes CanLoad of the DomainDataSource to become False (because we're editing). This in turn disables the DataGrid (IsEnabled is bound to it) and enables 'Cancel' and 'Save' buttons. However I'm running up against a race condition if I move quickly through rows in the DataGrid (just clicking random rows). The TextChanged presumably is being called on the textbox and confusing the DomainDataSource which then thinks there's been a change. So how should I disable the DataGrid while editing without having the race condition? One obvious solution would be to use KeyDown events to trigger the call to UpdateSource but I always hate having to do that.

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• How to temporarily replace one primitive type with another when compiling to different targets in c#

  - by Keith

  How to easily/quickly replace float's for doubles (for example) for compiling to two different targets using these two particular choices of primitive types? Discussion: I have a large amount of c# code under development that I need to compile to alternatively use float, double or decimals depending on the use case of the target assembly. Using something like “class MYNumber : Double” so that it is only necessary to change one line of code does not work as Double is sealed, and obviously there is no #define in C#. Peppering the code with #if #else statements is also not an option, there is just too much supporting Math operators/related code using these particular primitive types. I am at a loss on how to do this apparently simple task, thanks! Edit: Just a quick comment in relation to boxing mentioned in Kyles reply: Unfortunately I need to avoid boxing, mainly since float's are being chosen when maximum speed is required, and decimals when maximum accuracy is the priority (and taking the 20x+ performance hit is acceptable). Boxing would probably rules out decimals as a valid choice and defeat the purpose somewhat. Edit2: For reference, those suggesting generics as a possible answer to this question note that there are many issues which count generics out (at least for our needs). For an overview and further references see Using generics for calculations

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• Sharing large objects between ruby processes without a performance hit

  - by Gdeglin

  I have a Ruby hash that reaches approximately 10 megabytes if written to a file using Marshal.dump. After gzip compression it is approximately 500 kilobytes. Iterating through and altering this hash is very fast in ruby (fractions of a millisecond). Even copying it is extremely fast. The problem is that I need to share the data in this hash between Ruby on Rails processes. In order to do this using the Rails cache (file_store or memcached) I need to Marshal.dump the file first, however this incurs a 1000 millisecond delay when serializing the file and a 400 millisecond delay when serializing it. Ideally I would want to be able to save and load this hash from each process in under 100 milliseconds. One idea is to spawn a new Ruby process to hold this hash that provides an API to the other processes to modify or process the data within it, but I want to avoid doing this unless I'm certain that there are no other ways to share this object quickly. Is there a way I can more directly share this hash between processes without needing to serialize or deserialize it? Here is the code I'm using to generate a hash similar to the one I'm working with: @a = [] 0.upto(500) do |r| @a[r] = [] 0.upto(10_000) do |c| if rand(10) == 0 @a[r][c] = 1 # 10% chance of being 1 else @a[r][c] = 0 end end end @c = Marshal.dump(@a) # 1000 milliseconds Marshal.load(@c) # 400 milliseconds

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• How to localize an app on Google App Engine?

  - by Petri Pennanen

  What options are there for localizing an app on Google App Engine? How do you do it using Webapp, Django, web2py or [insert framework here]. 1. Readable URLs and entity key names Readable URLs are good for usability and search engine optimization (Stack Overflow is a good example on how to do it). On Google App Engine, key based queries are recommended for performance reasons. It follows that it is good practice to use the entity key name in the URL, so that the entity can be fetched from the datastore as quickly as possible. Currently I use the function below to create key names: import re import unicodedata def urlify(unicode_string): """Translates latin1 unicode strings to url friendly ASCII. Converts accented latin1 characters to their non-accented ASCII counterparts, converts to lowercase, converts spaces to hyphens and removes all characters that are not alphanumeric ASCII. Arguments unicode_string: Unicode encoded string. Returns String consisting of alphanumeric (ASCII) characters and hyphens. """ str = unicodedata.normalize('NFKD', unicode_string).encode('ASCII', 'ignore') str = re.sub('[^\w\s-]', '', str).strip().lower() return re.sub('[-\s]+', '-', str) This works fine for English and Swedish, however it will fail for non-western scripts and remove letters from some western ones (like Norwegian and Danish with their œ and ø). Can anyone suggest a method that works with more languages? 2. Translating templates Does Django internationalization and localization work on Google App Engine? Are there any extra steps that must be performed? Is it possible to use Django i18n and l10n for Django templates while using Webapp? The Jinja2 template language provides integration with Babel. How well does this work, in your experience? What options are avilable for your chosen template language? 3. Translated datastore content When serving content from (or storing it to) the datastore: Is there a better way than getting the *accept_language* parameter from the HTTP request and matching this with a language property that you have set with each entity?

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• How can I write classes that don't rely on "global" variables?

  - by Joel

  When I took my first programming course in university, we were taught that global variables were evil & should be avoided at all cost (since you can quickly develop confusing and unmaintainable code). The following year, we were taught object oriented programming, and how to create modular code using classes. I find that whenever I work with OOP, I use my classes' private variables as global variables, i.e., they can be (and are) read and modified by any function within the class. This isn't really sitting right with me, as it seems to introduce the same problems global variables had in languages like C. So I guess my question is, how do I stop writing classes with "global" variables? Would it make more sense to pretend I'm writing in a functional language? By this I mean having all functions take parameters & return values instead of directly modifying class variables. If I need to set any fields, I can just take the output of the function and assign it instead of having the function do it directly. This seems like it might make more maintainable code, at least for larger classes. What's common practice? Thanks!

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• decimal.TryParse() drops leading "1"

  - by Martin Harris

  Short and sweet version: On one machine out of around a hundred test machines decimal.TryParse() is converting "1.01" to 0.01 Okay, this is going to sound crazy but bare with me... We have a client applications that communicates with a webservice through JSON, and that service returns a decimal value as a string so we store it as a string in our model object: [DataMember(Name = "value")] public string Value { get; set; } When we display that value on screen it is formatted to a specific number of decimal places. So the process we use is string - decimal then decimal - string. The application is currently undergoing final testing and is running on more than 100 machines, where this all works fine. However on one machine if the decimal value has a leading '1' then it is replaced by a zero. I added simple logging to the code so it looks like this: Log("Original string value: {0}", value); decimal val; if (decimal.TryParse(value, out val)) { Log("Parsed decimal value: {0}", val); string output = val.ToString(format, CultureInfo.InvariantCulture.NumberFormat); Log("Formatted string value: {0}", output); return output; } On my machine - any every other client machine - the logfile output is: Original string value: 1.010000 Parsed decimal value: 1.010000 Formatted string value: 1.01 On the defective machine the output is: Original string value: 1.010000 Parsed decimal value: 0.010000 Formatted string value: 0.01 So it would appear that the decimal.TryParse method is at fault. Things we've tried: Uninstalling and reinstalling the client application Uninstalling and reinstalling .net 3.5 sp1 Comparing the defective machine's regional settings for numbers (using English (United Kingdom)) to those of a working machine - no differences. Has anyone seen anything like this or has any suggestions? I'm quickly running out of ideas... While I was typing this some more info came in: Passing a string value of "10000" to Convert.ToInt32() returns 0, so that also seems to drop the leading 1.

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• Normalizing (webdav) unicode paths

  - by Evert

  Hi guys, I'm working on a WebDAV implementation for PHP. In order to make it easier for Windows and other operating systems to work together, I need jump through some character encoding hoops. Windows uses ISO-8859-1 in it's HTTP request, while most other clients encode anything beyond ascii as UTF-8. My first approach was to ignore this altogether, but I quickly ran into issues when returning urls. I then figured it's probably best to normalize all urls. Using u¨ as an example. This will get sent over the wire by OS/X as u%CC%88 (this is codepoint U+0308) Windows sents this as: %FC (latin1) But, doing a utf8_encode on %FC, I get : %C3%BC (this is codepoint U+00FC) Should I treat %C3%BC and u%CC%88 as the same thing? If so.. how? Not touching it seems to work OK for windows. It somehow understands that it's a unicode character, but updating the same file throws an error (for no particular reason). I'd be happy to provide more information.

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• Java design: too many getters

  - by dege

  After writing a few lesser programs when learning Java the way I've designed the programs is with Model-View-Control. With using MVC I have a plethora of getter methods in the model for the view to use. It feels that while I gain on using MVC, for every new value added I have to add two new methods in the model which quickly get all cluttered with getter & setters. So I was thinking, maybe I should use the notifyObserver method that takes an argument. But wouldn't feel very smart to send every value by itself either so I figured, maybe if I send a kind of container with all the values, preferably only those that actually changed. What this would accomplish would be that instead of having a whole lot of getter methods I could just have one method in the model which put all relevant values in the container. Then in the view I would have a method called from the update which extracted the values from the container and assigning them to the correct fields. I have two questions concerning this. First: is this actually a viable way to do this. Would you recommend me doing something along these lines? Secondly: if I do use this plan and I don't want to keep sending fields that didn't actually change. How would I handle that without having to have if statements to check if the value is not null for every single value?

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• Ideal Multi-Developer Lamp Stack?

  - by devians

  I would like to build an 'ideal' lamp development stack. Dual Server (Virtualised, ESX) Apache / PHP on one, Databases (MySQL, PgSQL, etc) on the other. User (Developer) Manageable mini environments, or instance. Each developer instance shares the top level config (available modules and default config etc) A developer should have control over their apache and php version for each project. A developer might be able to change minor settings, ie magicquotes on for legacy code. Each project would determine its database provider in its code The idea is that it is one administrate-able server that I can control, and provide globally configured things like APC, Memcached, XDebug etc. Then by moving into subsets for each project, i can allow my users to quickly control their environments for various projects. Essentially I'm proposing the typical system of a developer running their own stack on their own machine, but centralised. In this way I'd hope to avoid problems like Cross OS code problems, database inconsistencies, slightly different installs producing bugs etc. I'm happy to manage this in custom builds from source, but if at all possible it would be great to have a large portion of it managed with some sort of package management. We typically use CentOS, so yum? Has anyone ever built anything like this before? Is there something turnkey that is similar to what I have described? Are there any useful guides I should be reading in order to build something like this?

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• Translate an exception into 404 from Application_Error

  - by Dmitriy Nagirnyak

  Hi, First of all, quickly what exactly I want to achieve: translate particular exception into the HTTP 404 so the ASP.NET can handle it further. I am handling exceptions in the ASP.NET (MVC2) this way: protected void Application_Error(object sender, EventArgs e) { var err = Server.GetLastError(); if (err == null) return; err = err.GetBaseException(); var noObject = err as ObjectNotFoundException; if (noObject != null) HandleObjectNotFound(); var handled = noObject != null; if (!handled) Logger.Fatal("Unhandled exception has occured in application.", err); } private void HandleObjectNotFound() { Server.ClearError(); Response.Clear(); // new HttpExcepton(404, "Not Found"); // Throw or not to throw? Response.StatusCode = 404; Response.StatusDescription = "Not Found"; Response.StatusDescription = "Not Found"; Response.Write("The whole HTML body explaining whata 404 is??"); } The problem is that I cannot configure default customErrors to work with it. When it is on then it never redirects to the page specified in customErrors: <error statusCode="404" redirect="404.html"/>. I also tried to raise new HttpExcepton(404, "Not Found") from the handler but then the response code is 200 which I don't understand why. So the questions are: What is the proper way of translating AnException into HTTP 404 response? How does customErrors section work when handling exceptions in Application_Error? Why throwing HttpException(404) renders (blank) page with success (200) status? Thanks, Dmitriy.

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• Qt QFileDialog - native dialogs only with static functions?

  - by darron

  I'm trying to simply save a file. However, I need a filename entered without a suffix to automatically get a default suffix (which setDefaultSuffix() does). I'd rather not completely lose the native save dialog just for this. exec() is not overloaded from QDialog, so it totally bypasses the native hook (ignoring the DontUseNativeDialog option even if it's false). If I disable the file overwrite warning and append the default suffix myself after the function returns, then I'd be re-opening the dialog if the user did not want to overwrite... and that's just ugly. Is there some signal I can catch and quickly inject the default suffix if it's not there? I'm guessing not, since it's a native dialog. Is there something I'm doing wrong with the filter? I only have one filter choice. It should use that extension. This seems pretty lame. Launching the save dialog and simply typing "test" should never result in an extensionless file. "test.", yes. "test" no way. That'll really confuse the users when they hit Load and can't see the file they just saved. I guess the cross-platform part of Qt is giving me lowest common denominator file dialog functionality?

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• Parsing Lisp S-Expressions with known schema in C#

  - by Drew Noakes

  I'm working with a service that provides data as a Lisp-like S-Expression string. This data is arriving thick and fast, and I want to churn through it as quickly as possible, ideally directly on the byte stream (it's only single-byte characters) without any backtracking. These strings can be quite lengthy and I don't want the GC churn of allocating a string for the whole message. My current implementation uses CoCo/R with a grammar, but it has a few problems. Due to the backtracking, it assigns the whole stream to a string. It's also a bit fiddly for users of my code to change if they have to. I'd rather have a pure C# solution. CoCo/R also does not allow for the reuse of parser/scanner objects, so I have to recreate them for each message. Conceptually the data stream can be thought of as a sequence of S-Expressions: (item 1 apple)(item 2 banana)(item 3 chainsaw) Parsing this sequence would create three objects. The type of each object can be determined by the first value in the list, in the above case "item". The schema/grammar of the incoming stream is well known. Before I start coding I'd like to know if there are libraries out there that do this already. I'm sure I'm not the first person to have this problem.

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• What can cause Windows to unhook a low level (global) keyboard hook?

  - by Davy8

  We have some global keyboard hooks installed via SetWindowsHookEx with WH_KEYBOARD_LL that appear to randomly get unhooked by Windows. We verified that they hook was no longer attached because calling UnhookWindowsHookEx on the handle returns false. (Also verified that it returns true when it was working properly) There doesn't seem to be a consistent repro, I've heard that they can get unhooked due to timeouts or exceptions getting thrown, but I've tried both just letting it sit on a breakpoint in the handling method for over a minute, as well as just throwing a random exception (C#) and it still appears to work. In our callback we quickly post to another thread, so that probably isn't the issue. I've read about solutions in Windows 7 for setting the timeout higher in the registry because Windows 7 is more aggressive about the timeouts apparently (we're all running Win7 here, so not sure if this occurs on other OS's) , but that doesn't seem like an ideal solution. I've considered just having a background thread running to refresh the hook every once in a while, which is hackish, but I don't know of any real negative consequences of doing that, and it seems better than changing a global Windows registry setting. Any other suggestions or solutions? The delegates are not being GC'd since they're static members, which is one cause that I've read about.

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• How to use Java varargs with the GWT Javascript Native Interface? (aka, "GWT has no printf()")

  - by markerikson

  I'm trying to quickly learn GWT as part of a new project. I found out that GWT doesn't implement Java's String.format() function, so there's no printf()-like functionality. I knew that some printf() implementations exist for Javascript, so I figured I could paste one of those in as a GWT Javascript Native Interface function. I ran into problems, and decided I'd better make sure that the varargs values were being passed in correctly. That's where things got ugly. First, some example code: // From Java, call the JSNI function: test("sourceString", "params1", "params2", "params3"); .... public static native void test(Object... params) /*-{ // PROBLEM: this kills GWT! // alert(params.length); // returns "function" alert(typeof(params)); // returns "[Ljava.lang.Object;@b97ff1" alert(params); }-*/; The GWT docs state that "calling a varargs JavaScript method from Java will result in the callee receiving the arguments in an array". I figured that meant I could at least check params.length, but accessing that throws a JavascriptException wrapped in an UmbrellaException, with no real information. When I do "typeof(params)", it returns "function". As if that weren't odd enough, if I check the string value of params, it returns what appears to be a string version of a Java reference. So, I guess I'm asking a few different questions here: 1) How do GWT/JSNI varargs actually work, and do I need to do something special to pass in values? 2) What is actually going on here? 3) Is there any easier way to get printf()-style formatting in a GWT application?

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• Formatting inline many-to-many related models presented in django admin

  - by Jonathan

  I've got two django models (simplified): class Product(models.Model): name = models.TextField() price = models.IntegerField() class Invoice(models.Model): company = models.TextField() customer = models.TextField() products = models.ManyToManyField(Product) I would like to see the relevant products as a nice table (of product fields) in an Invoice page in admin and be able to link to the individual respective Product pages. My first thought was using the admin's inline - but django used a select box widget per related Product. This isn't linked to the Product pages, and also as I have thousands of products, and each select box independently downloads all the product names, it quickly becomes unreasonably slow. So I turned to using ModelAdmin.filter_horizontal as suggested here, which used a single instance of a different widget, where you have a list of all Products and another list of related Products and you can add\remove products in the later from the former. This solved the slowness, but it still doesn't show the relevant Product fields, and it ain't linkable. So, what should I do? tweak views? override ModelForms? I Googled around and couldn't find any example of such code...

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• php remove button keeps retreiving posted information

  - by Doug

  Hi every1! im quickly finding im quite the beginner to php, so please bare with me! I have a quick problem, I have a remove button for a shopping cart and the code works for it everytime except for the last product thats in the cart. If a person pushes the addtoCart button the URL is reloaded with ?buyproduct=$productNumber and when the remove button is pushed the product is removed. Right so everything is good, but when you try to remove the last item, it keeps reading the product thats in the URL. so the quantity remains 1 for the current $productNumber. i've tried adding the action in the form method tag so that the page reloads without the ?buyproduct=$productNumber, which does work however there are page numbers and sections that were also in the URL and these get reset also. i know the remove is working because once the ?buyproduct=$productNumber is gone from the URL (which can happen for example if they go to another section in the catalog) then the cart can be completely emptied. Thank you so much ahead of time for any1's help, I've used this site before and you guys are genius's!

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• Query by datetime in JDOQL / Java / GAE

  - by Jan Kuboschek

  I'm working on a GAE app. I want to query datastore and retrieve all records between startDate and endDate. Each record has a datetime field. I'm using a query similar to this (the below code is something I quickly grabbed - I'm not near my developer machine.): Query query = pm.newQuery(Employee.class); query.setFilter("lastName == lastNameParam"); query.setOrdering("hireDate desc"); query.declareParameters("String lastNameParam"); try { List results = (List) query.execute("Smith"); if (results.iterator().hasNext()) { for (Employee e : results) { // ... } } else { // ... no results ... } } finally { query.closeAll(); } How do I have to format the date to form a correctly working query? How is the datetime stamp stored in datastore? As timestamp? Fully formatted? I can't find ANY information on this. Please help.

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• Java split xml file

  - by CC

  Hi all, I'm working on a piece of code to split files. I want to split flat file (that's ok, it is working fine) and xml file. The idea is to split based of a number of files to split: I have a file, and I want to split it in x files (x is a parameters). I'm doing the split by taking the size of the file and spliting the size by the number of files to split. Then, mysolution was to use a BufferedReader and to use it like while ((n = reader.read(buffer, 0, buffer.length)) != -1) { { The main problem is that for the xml file I cannot just split it, but I have to split it based on a block delimited by a start xml tag and end xml tag: <start tag> bla bla xml stuff </end tag> So I cannot cut a block at the middle. So if when I'm at the half of a block, is the size of my new file is greater than my max, I will have to read until the end of the tag, and then, to start a next file. The problem is that I have all sort of cases, and is a bit difficult to search the end tag. - the block reads a text until the middle of the end tag - the block reads a text until the end of the end tag, and no more other caracter after - etc and in the same time to have a loop and read the next block. Some times the end of a block concatenated with the start of the next one, I have the end xml tag. I hope you get the idea. My question is, does anyone have some algorithm that does that more accurate and who i treating all special cases ? The idea is to split the file as quickly as possible. Thanks alot.

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• Which technology is best suited to store and query a huge readonly graph?

  - by asmaier

  I have a huge directed graph: It consists of 1.6 million nodes and 30 million edges. I want the users to be able to find all the shortest connections (including incoming and outgoing edges) between two nodes of the graph (via a web interface). At the moment I have stored the graph in a PostgreSQL database. But that solution is not very efficient and elegant, I basically need to store all the edges of the graph twice (see my question PostgreSQL: How to optimize my database for storing and querying a huge graph). It was suggested to me to use a GraphDB like neo4j or AllegroGraph. However the free version of AllegroGraph is limited to 50 million nodes and also has a very high-level API (RDF), which seems too powerful and complex for my problem. Neo4j on the other hand has only a very low level API (and the python interface is not mature yet). Both of them seem to be more suited for problems, where nodes and edges are frequently added or removed to a graph. For a simple search on a graph, these GraphDBs seem to be too complex. One idea I had would be to "misuse" a search engine like Lucene for the job, since I'm basically only searching connections in a graph. Another idea would be, to have a server process, storing the whole graph (500MB to 1GB) in memory. The clients could then query the server process and could transverse the graph very quickly, since the graph is stored in memory. Is there an easy possibility to write such a server (preferably in Python) using some existing framework? Which technology would you use to store and query such a huge readonly graph?

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• Anything speaking against the bitnami.org Ruby/Rails/Redmine Stack?

  - by Pekka

  I am looking to set up a Redmine server on a Windows virtual machine on my local workstation. (Background in this related question.) I have zero knowledge of Ruby nor Rails, and while Redmine may be the opportunity to dip into those platforms somewhat, my first goal is to get it running as quickly and easily as possible. For that, I am eyeing the Bitnami Redmine Package. It promises point-and-click install, and a self-contained environment with everything you need. Apart from the learning factor, are there any serious limitations this method implies? Any serious cutdowns in customizability? I will be wanting to customize the template right away, for example, and install plugins. The package looks o.k. to me but before I install it, I was curious to know whether anybody would advise against it and why. Edit: The first impression is great. From 0 to a working Redmine installation in twelve minutes! Wow.

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• Good hash function for a 2d index

  - by rlbond

  I have a struct called Point. Point is pretty simple: struct Point { Row row; Column column; // some other code for addition and subtraction of points is there too } Row and Column are basically glorified ints, but I got sick of accidentally transposing the input arguments to functions and gave them each a wrapper class. Right now I use a set of points, but repeated lookups are really slowing things down. I want to switch to an unordered_set. So, I want to have an unordered_set of Points. Typically this set might contain, for example, every point on a 80x24 terminal = 1920 points. I need a good hash function. I just came up with the following: struct PointHash : public std::unary_function<Point, std::size_t> { result_type operator()(const argument_type& val) const { return val.row.value() * 1000 + val.col.value(); } }; However, I'm not sure that this is really a good hash function. I wanted something fast, since I need to do many lookups very quickly. Is there a better hash function I can use, or is this OK?

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• Javascript scope chain

  - by Geromey

  Hi, I am trying to optimize my program. I think I understand the basics of closure. I am confused about the scope chain though. I know that in general you want a low scope (to access variables quickly). Say I have the following object: var my_object = (function(){ //private variables var a_private = 0; return{ //public //public variables a_public : 1, //public methods some_public : function(){ debugger; alert(this.a_public); alert(a_private); }; }; })(); My understanding is that if I am in the some_public method I can access the private variables faster than the public ones. Is this correct? My confusion comes with the scope level of this. When the code is stopped at debugger, firebug shows the public variable inside the this keyword. The this word is not inside a scope level. How fast is accessing this? Right now I am storing any this.properties as another local variable to avoid accessing it multiple times. Thanks very much!

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• Finding subsets that can be completed to tuples without duplicates

  - by Jules

  We have a collection of sets A_1,..,A_n. The goal is to find new sets for each of the old sets. newA_i = {a_i in A_i such that there exist (a_1,..,a_n) in (A1,..,An) with no a_k = a_j for all k and j} So in words this says that we remove all the elements from A_i that can't be used to form a tuple (a_1,..a_n) from the sets (A_1,..,A_n) such that the tuple doesn't contain duplicates. My question is how to compute these new sets quickly. If you just implement this definition by generating all possible v's this will take exponential time. Do you know a better algorithm? Edit: here's an example. Take A_1 = {1,2,3,4} A_2 = {2}. Now the new sets look like this: newA_1 = {1,3,4} newA_2 = {2} The 2 has been removed from A_1 because if you choose it the tuple will always be (2,2) which is invalid because it contains duplicates. On the other hand 1,3,4 are valid because (1,2), (3,2) and (4,2) are valid tuples. Another example: A_1 = {1,2,3} A_2 = {1,4,5} A_3 = {2,4,5} A_4 = {1,2,3} A_5 = {1,2,3} Now the new sets are: newA_1 = {1,2,3} newA_2 = {4,5} newA_3 = {4,5} newA_4 = {1,2,3} newA_5 = {1,2,3} The 1 and 2 are removed from sets 2 and 3 because if you choose the 1 or 2 from these sets you'll only have 2 values left for sets 1, 4 and 5, so you will always have duplicates in tuples that look like (_,1,_,_,_) or like (_,_,2,_,_).

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• Advice on coding Perl to work like PHP

  - by user272273

  I am first and foremost a perl coder, but like many, also code in PHP for client work, especially web apps. I am finding that I am duplicating a lot of my projects in the two languages, but using different paradigms (e.g. for handling cgi input and session data) or functions. What I would like to do is start to code my Perl in a way which is structured more like PHP, so that I a) am keeping one paradigm in my head b) can more quickly port over scripts from one to the other Specifically, I am asking if people could advise how you might do the following in perl? 1) Reproduce the functionality of $_SESSION, $_GET etc. e.g. by wrapping up the param() method of CGI.pm, a session library? 2) Templating library that is similar to PHP I am used to mixing my code and HTML in the PHP convention. e.g. i <h1>HTML Code here</h1> <? print "Hello World\b"; ?> Can anybody advise on which perl templating engine (and possibly configuration) will allow me to code similarly? 3) PHP function library Anybody know of a library for perl which reproduces a lot of the php inbuilt functions?

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