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  • Java-Hibernate: How can I translate these tables to hibernate annotations?

    - by penas
    I need to create a simple application using these tables: http://stackoverflow.com/questions/2612848/are-these-tables-respect-the-3nf-database-normalization I have created the application using simple old JDBC, but I would like to see how the application would look like using Hibernate, but I don't know how to put the sql code in java. I have found LOTS of examples, but I'm pretty much confused about using Hibernate and I don't know If I made such a good joob. For example, for the first three tables: AUTHOR table * Author_ID, PK * First_Name * Last_Name TITLES table * TITLE_ID, PK * NAME * Author_ID, FK DOMAIN table * DOMAIN_ID, PK * NAME * TITLE_ID, FK The code in java: Table 1 @Entity @Table(name = "AUTHORS", schema = "LIBRARY") public class Author{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "Author_ID") private int authorId; @Column(name = "First_Name", nullable = false, length = 50) private String firstName; @Column(name = "Last_Name", nullable = false, length = 40) private String lastName; @OneToMany @JoinColumn(name = "Title_ID") private List<Title> titles; Table 2 @Entity @Table(name = "TITLES") public class Title{ @Id @Column(name = "Title_ID") private int titleID; @Column(name = "Name", nullable = false, length = 50) private String name; @ManyToOne @JoinColumn(name = "Domain_ID") private Domain domains; Table 3 @Entity @Table(name = "DOMAINS") public class Domain{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name = "Domain_ID") private int Domain_ID; @Column(name = "Name", nullable = false, length = 50) private String name; @OneToOne(mappedBy = "domains") private Title title; } Any good? :)

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  • Howto use predicates in LINQ to Entities for Entity Framework objects

    - by user274947
    I'm using LINQ to Entities for Entity Framework objects in my Data Access Layer. My goal is to filter as much as I can from the database, without applying filtering logic on in-memory results. For that purpose Business Logic Layer passes a predicate to Data Access Layer. I mean Func<MyEntity, bool> So, if I use this predicate directly, like public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.Where(x => isMatched(x)); } I'm getting the exception [System.NotSupportedException] --- {"The LINQ expression node type 'Invoke' is not supported in LINQ to Entities."} Solution in that question suggests to use AsExpandable() method from LINQKit library. But again, using public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.AsExpandable().Where(x => isMatched(x)); } I'm getting the exception Unable to cast object of type 'System.Linq.Expressions.FieldExpression' to type 'System.Linq.Expressions.LambdaExpression' Is there way to use predicate in LINQ to Entities query for Entity Framework objects, so that it is correctly transformed it into a SQL statement. Thank you.

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  • Android - Where to store generated bitmaps?

    - by Josh
    I've got an app which dynamically generates anywhere from 6 to 100 small bitmaps for the user to move around the screen in a given session. I currently generate them in onCreate and store them to the sd card, so that after an orientation change I can grab them out of external storage and display them again. However, this takes time (the loading) and I'd like to keep the bitmap references around between lifecyle changes for quicker access. My question is, is there a better place to store my generated bitmaps? I was thinking about creating a static storage library in my base activity, something that would only need to be reloaded when the app is completely removed from memory (shutdown, other apps need resources, 30 minute restart, etc). Ideally, I'd like the user to be able to back out to the title screen, click a "Resume" button, and in onCreate I just have access to those resident bitmap references instead of having to load them from storage again. For this reason I don't think Activity.onRetainNonConfigurationInstance is what I need. Alternatively, is there a better way to handle multiple generated bitmaps than what I'm doing or the plan I described?

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  • How can I get a iterable resultset from the database using pdo, instead of a large array?

    - by Tchalvak
    I'm using PDO inside a database abstraction library function query. I'm using fetchAll(), which if you have a lot of results, can get memory intensive, so I want to provide an argument to toggle between a fetchAll associative array and a pdo result set that can be iterated over with foreach and requires less memory (somehow). I remember hearing about this, and I searched the PDO docs, but I couldn't find any useful way to do that. Does anyone know how to get an iterable resultset back from PDO instead of just a flat array? And am I right that using an iterable resultset will be easier on memory? I'm using Postgresql, if it matters in this case. . . . The current query function is as follows, just for clarity. /** * Running bound queries on the database. * * Use: query('select all from players limit :count', array('count'=>10)); * Or: query('select all from players limit :count', array('count'=>array(10, PDO::PARAM_INT))); **/ function query($sql_query, $bindings=array()){ DatabaseConnection::getInstance(); $statement = DatabaseConnection::$pdo->prepare($sql_query); foreach($bindings as $binding => $value){ if(is_array($value)){ $statement->bindParam($binding, $value[0], $value[1]); } else { $statement->bindValue($binding, $value); } } $statement->execute(); // TODO: Return an iterable resultset here, and allow switching between array and iterable resultset. return $statement->fetchAll(PDO::FETCH_ASSOC); }

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  • problem in handling menu - submenu based on spring security

    - by Nirmal
    Hi All... I have configured spring security core plugin using requestmap table inside the database.. Now inside requestmap table I have all the possible urls and it's equivalent roles who can access that url... Now I want to generate menus and submenus based on the urls stored in requestmap table... So my requirement is to check the urls of menu & submenus against the logged in users privileges... And if logged in user has any one privilege then I need to display that main menu and the available submenus.... For e.g. I have a menu in my project called user which has a following submenus : **Users (main menu)** Manage Users (sub menu) Import Users (sub menu) Now inside my header.gsp I have successfully achieved the above requirement using if else condition, like : if ( privs.contains("/users/manageUsers") || privs.contains("/users/importUsers")) here privs are the list of urls from requestmap table for logged in user. But I want to achieve these using spring security tag lib, so for comparing urls I have find following tag from spring security core documentation : <sec:access url="/users/manageUsers"> But i am bit confuse that how I can replace or condition using tag library.. Is there any tag available which checks from multiple urls and evaluate it to true or false ? Of course I can do using sec:access tag with some flag logic, but is there any tags available which can fulfill my requirement directly ? Thanks in advance...

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  • How does one gets started with Winforms style applications on Win32?

    - by Billy ONeal
    EDIT: I'm extremely tired and frustrated at the moment -- please ignore that bit in this question -- I'll edit it in the morning to be better. Okay -- a bit of background: I'm a C++ programmer mostly, but the only GUI stuff I've ever done was on top of .NET's WinForms platform. I'm completely new to Windows GUI programming, and despite Petzold's excellent book, I'm extremely confused. Namely, it seems that most every reference on getting started with Win32 is all about drawing lines and curves and things -- a topic about which (at least at present time) I couldn't care less. I need a checked list box, a splitter, and a textbox -- something that would take less than 10 minutes to do in Winforms land. It has been recommended to me to use the WTL library, which provides an implementation of all three of these controls -- but I keep getting hung up on simple things, such as getting the damn controls to use the right font, and getting High DPI working correctly. I've spent two freaking days on this, and I can't help but think there has to be a better reference for these kinds of things than I've been able to find. Petzold's book is good, but it hasn't been updated since Windows 95 days, and there's been a LOT changed w.r.t. how applications should be correctly developed since it was published. I guess what I'm looking for is a modern Petzold book. Where can I find such a resource, if any?

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  • Efficient way to maintain a sorted list of access counts in Python

    - by David
    Let's say I have a list of objects. (All together now: "I have a list of objects.") In the web application I'm writing, each time a request comes in, I pick out up to one of these objects according to unspecified criteria and use it to handle the request. Basically like this: def handle_request(req): for h in handlers: if h.handles(req): return h return None Assuming the order of the objects in the list is unimportant, I can cut down on unnecessary iterations by keeping the list sorted such that the most frequently used (or perhaps most recently used) objects are at the front. I know this isn't something to be concerned about - it'll make only a miniscule, undetectable difference in the app's execution time - but debugging the rest of the code is driving me crazy and I need a distraction :) so I'm asking out of curiosity: what is the most efficient way to maintain the list in sorted order, descending, by the number of times each handler is chosen? The obvious solution is to make handlers a list of (count, handler) pairs, and each time a handler is chosen, increment the count and resort the list. def handle_request(req): for h in handlers[:]: if h[1].handles(req): h[0] += 1 handlers.sort(reverse=True) return h[1] return None But since there's only ever going to be at most one element out of order, and I know which one it is, it seems like some sort of optimization should be possible. Is there something in the standard library, perhaps, that is especially well-suited to this task? Or some other data structure? (Even if it's not implemented in Python) Or should/could I be doing something completely different?

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  • I don't like Python functions that take two or more iterables. Is it a good idea?

    - by Xavier Ho
    This question came from looking at this question on Stackoverflow. def fringe8((px, py), (x1, y1, x2, y2)): Personally, it's been one of my pet peeves to see a function that takes two arguments with fixed-number iterables (like a tuple) or two or more dictionaries (Like in the Shotgun API). It's just hard to use, because of all the verbosity and double-bracketed enclosures. Wouldn't this be better: >>> class Point(object): ... def __init__(self, x, y): ... self.x = x ... self.y = y ... >>> class Rect(object): ... def __init__(self, x1, y1, x2, y2): ... self.x1 = x1 ... self.y1 = y1 ... self.x2 = x2 ... self.y2 = y2 ... >>> def fringe8(point, rect): ... # ... ... >>> >>> point = Point(2, 2) >>> rect = Rect(1, 1, 3, 3) >>> >>> fringe8(point, rect) Is there a situation where taking two or more iterable arguments is justified? Obviously the standard itertools Python library needs that, but I can't see it being pretty in maintainable, flexible code design.

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  • reading newlines with FORMAT statement

    - by peter.murray.rust
    I'm writing a preprocessor and postprocessor for Fortran input and output using FORMAT-like statements (there are reasons not to use a FORTRAN library). I want to treat the new line ("/") character correctly. I don't have a Fortran compiler immediately to hand. Is there a simple algorithm for working out how many newlines are written or consumed (This post just gives reading examples) [Please assume a FORTRAN77-like mentality in the FORTRAN code and correct any FORTRAN syntax on my part] UPDATE: no comments yet so I am reduced to finding a compiler and running it myself. I'll post the answers if I'm not beaten to it. No-one commented I had the format syntax wrong. I've changed it but there may still be errors Assume datafile 1 a b c d etc... (a) does the READ command always consume a newline? does READ(1, '(A)') A READ(1, '(A)') B give A='a' and B='b' (b) what does READ(1,'(A,/)') A READ(1,'(A)') B give for B? (I would assume 'c') (c) what does READ(1, '(/)') READ(1, '(A)') A give for A (is it 'b' or 'c') (d) what does READ(1,'(A,/,A)') A, B READ(1,'(A)') C give for A and B and C(can I assume 'a' and 'b' and 'c') (e) what does READ(1,'(A,/,/,A)') A, B READ(1,'(A)') C give for A and B and C(can I assume 'a' and 'c' and 'd')? Are there any cases in which the '/' is redundant?

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  • How to pass data to a C++0x lambda function that will run in a different thread?

    - by Dimitri C.
    In our company we've written a library function to call a function asynchronously in a separate thread. It works using a combination of inheritance and template magic. The client code looks as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, &DemoThread::SomeFunction, stringToPassByValue); Since the introduction of lambda functions I'd like to use it in combination with lambda functions. I'd like to write the following client code: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=]() { const std::string someCopy = stringToPassByValue; }); Now, with the Visual C++ 2010 this code doesn't work. What happens is that the stringToPassByValue is not copied. Instead the "capture by value" feature passes the data by reference. The result is that if the function is executed after stringToPassByValue has gone out of scope, the application crashes as its destructor is called already. So I wonder: is it possible to pass data to a lambda function as a copy? Note: One possible solution would be to modify our framework to pass the data in the lambda parameter declaration list, as follows: DemoThread thread; std::string stringToPassByValue = "The string to pass by value"; AsyncCall(thread, [=](const std::string stringPassedByValue) { const std::string someCopy = stringPassedByValue; } , stringToPassByValue); However, this solution is so verbose that our original function pointer solution is both shorter and easier to read. Update: The full implementation of AsyncCall is too big to post here. In short, what happens is that the AsyncCall template function instantiates a template class holding the lambda function. This class is derived from a base class that contains a virtual Execute() function, and upon an AsyncCall() call, the function call class is put on a call queue. A different thread then executes the queued calls by calling the virtual Execute() function, which is polymorphically dispatched to the template class which then executes the lambda function.

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  • Browser Issue: Charts are not rendered on IE8

    - by Rachel
    We have inhouse library which uses canvas for displaying charts in my application. And dojo as scripting language.Everything is fine, but my charts are not appearing in IE8. I google about this, and found that there is some VML issue in IE8. I found this: var printChart = function(time, freq){ if (!document.namespaces['g_vml_']) { document.namespaces.add('g_vml_', 'urn:schemas-microsoft-com:vml', '#default#VML'); } if (!document.namespaces['g_o_']) { document.namespaces.add('g_o_', 'urn:schemas-microsoft-com:office:office', '#default#VML'); } if (freq === undefined) { this.freq = "1mi"; } if (time === undefined) { this.time = "1dy"; } self.reload(); } Now I was trying to add this in my DOJO code and that is creating problem. As when I do document.namespace I get firebug error 'document.namespaces is undefined'. Q: How can we fix this, are the any better alternative approaches for the same, basic problem am having is browser related, charts are rendered properly on other browsers but not on IE8, any suggestions ? Update: What are ways to deal with such cross browser issue ?

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  • java: libraries for immutable functional-style data structures

    - by Jason S
    This is very similar to another question (Functional Data Structures in Java) but the answers there are not particularly useful. I need to use immutable versions of the standard Java collections (e.g. HashMap / TreeMap / ArrayList / LinkedList / HashSet / TreeSet). By "immutable" I mean immutable in the functional sense (e.g. purely functional data structures), where updating operations on the data structure do not change the original data, but instead return a new instance of the same kind of data structure. Also typically new and old instances of the data structure will share immutable data to be efficient in time and space. From what I can tell my options include: Functional Java Scala Clojure but I'm not sure whether any of these are particularly appealing to me. I have a few requirements/desirements: the collections in question should be usable directly in Java (with the appropriate libraries in the classpath). FJ would work for me; I'm not sure if I can use Scala's or Clojure's data structures in Java w/o having to use the compilers/interpreters from those languages and w/o having to write Scala or Clojure code. Core operations on lists/maps/sets should be possible w/o having to create function objects with confusing syntaxes (FJ looks slightly iffy) They should be efficient in time and space. I'm looking for a library which ideally has done some performance testing. FJ's TreeMap is based on a red-black tree, not sure how that rates. Documentation / tutorials should be good enough so someone can get started quickly using the data structures. FJ fails on that front. Any suggestions?

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  • What is the optimum way to select the most dissimilar individuals from a population?

    - by Aaron D
    I have tried to use k-means clustering to select the most diverse markers in my population, for example, if we want to select 100 lines I cluster the whole population to 100 clusters then select the closest marker to the centroid from each cluster. The problem with my solution is it takes too much time (probably my function needs optimization), especially when the number of markers exceeds 100000. So, I will appreciate it so much if anyone can show me a new way to select markers that maximize diversity in my population and/or help me optimize my function to make it work faster. Thank you # example: library(BLR) data(wheat) dim(X) mdf<-mostdiff(t(X), 100,1,nstart=1000) Here is the mostdiff function that i used: mostdiff <- function(markers, nClust, nMrkPerClust, nstart=1000) { transposedMarkers <- as.array(markers) mrkClust <- kmeans(transposedMarkers, nClust, nstart=nstart) save(mrkClust, file="markerCluster.Rdata") # within clusters, pick the markers that are closest to the cluster centroid # turn the vector of which markers belong to which clusters into a list nClust long # each element of the list is a vector of the markers in that cluster clustersToList <- function(nClust, clusters) { vecOfCluster <- function(whichClust, clusters) { return(which(whichClust == clusters)) } return(apply(as.array(1:nClust), 1, vecOfCluster, clusters)) } pickCloseToCenter <- function(vecOfCluster, whichClust, transposedMarkers, centers, pickHowMany) { clustSize <- length(vecOfCluster) # if there are fewer than three markers, the center is equally distant from all so don't bother if (clustSize < 3) return(vecOfCluster[1:min(pickHowMany, clustSize)]) # figure out the distance (squared) between each marker in the cluster and the cluster center distToCenter <- function(marker, center){ diff <- center - marker return(sum(diff*diff)) } dists <- apply(transposedMarkers[vecOfCluster,], 1, distToCenter, center=centers[whichClust,]) return(vecOfCluster[order(dists)[1:min(pickHowMany, clustSize)]]) } }

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  • Why won't my Setup Project Perform my Custom Registration Process

    - by Jordan S
    I am trying to write an Setup Project/Installer for a class library driver that I wrote in C# using Visual Studio 2008. The driver project has a section of code that looks like this... [ComRegisterFunction] public static void RegisterASCOM(Type t) { Trace.WriteLine("Registration Started."); DoRegistration(true); } In the driver project Properties - "Assembly Information" I have set checked the box that says Make COM-Visible = true. I added a Setup Project to the solution in VS, added the output dll from the driver project so that it installs on the target machine and set the Register property of the dll to "vsdraCOM". So, my understanding is that when the installer runs it SHOULD execute the methods of the dll that are marked with [COMRegisterFunction]. Using SysInternals Debug View I can monitor when the above code snippet is hit by watching for the "Registration started" text to show up in the window. When I build the solution, I can see the text show up so I know the driver is registering properly. The problem is that when I run the installer, I don't think it is doing the registration bit. I see nothing show up in Debug View. And if i try to access my driver via another application I get an error saying it "Cannot create ActiveX object". Why does the registration not occur during the install process? The driver does register for COM but it does NOT call my custom registration method. Does anyone have and suggestions of what I could be missing? Is there another way I can debug this? (I can provide more code if anyone want's to take a look!!)

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  • Preloading CSS Background Images

    - by Peanuts
    Hello guys, I have a hidden contact form which is deployed clicking on a button. Its fields are set as CSS background images, and they always appears a bit later than the div that have been toggled. I was using this snippet in the <head> section, but with no luck (after I cleared the cache) : <script type="text/javascript"> $(document).ready(function() { pic = new Image(); pic2 = new Image(); pic3 = new Image(); pic.src="<?php bloginfo('template_directory'); ?>/images/inputs/input1.png"; pic2.src="<?php bloginfo('template_directory'); ?>/images/inputs/input2.png"; pic3.src="<?php bloginfo('template_directory'); ?>/images/inputs/input3.png"; }); </script> I'm using jQuery as my library, and it would be cool if I could use it as well for arranging this issue. Thanks for your thoughs.

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  • gwt seperate modules with no code sharing

    - by Code freak
    Hi, I have to make a web application using GWT. The project has a core module that'll expose a set of apis to be used by other apps; each of these app are unrelated. Each shall be loaded in a separate iframe. My idea was to compile core into core.js and each app shall have its own app1.js app2.js and so on... App1 script type="text/javascript" src="core.js" ></script> script type="text/javascript" src="app1.js" ></script> with this design, due to browser caching, each app laod only the app.js which should be smaller ~20kb in size. Making a core module is straightforward but the apps are problematic. The reason being after compilation, each app contains the entire GWT library - this substantially increases the download size of the complete webapp. Can anyone suggest a way to get aroung this problem ? I've checked similar questions on SO, but failed to find a simple working answer fr the problem. Thanks for any help.

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  • Overriding Code Igniter 2.14's global_xss_filtering settting

    - by user2353007
    I have created the following file at: application/core/MY_Security.php <?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); /* * Does not work with global xss */ class MY_Security extends CI_Security { function xss_clean($str, $is_image = FALSE) { $CI =& get_instance(); $CI->load->library('My_cleaner'); return $CI->my_cleaner->clean_html($str); } } this works great for $this-input-post('post_var', TRUE); and $this-security-xss_clean($input); It is working very well except when I go into application/config/config.php and change $config['global_xss_filtering] = FALSE; to $config['global_xss_filtering] = TRUE; in that case, I just get a white page on every controllers action/function. Does anybody know what else I have to change to get global_xss_filtering = TRUE; to work when overriding the xss_clean function in system/core/Security.php through application/core/MY_Security.php? I'm guessing it might be something with the loader but I'm not sure where to start. The next option is to just replace the function in the system/core/Security.php file which I am trying to avoid. Thanks.

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  • App is fast on 3GS but slow on 3G

    - by Anthony Chan
    Hi all, I'm new to computer coding and have just finished coding an app and tested it on both 3G and 3GS. On 3GS, it worked as normal as on the simulator. However, when I tried to run it on 3G, the app becomes extremely slow. I'm not sure what's the reason and I hope someone could shed some light on me. Generally, my app has a couple of view controller classes, with one of them being the title page, one being the main page, one is setting, etc. I used a dissolve to transition from the title page to the main page. But even this simple transition shows un-smooth performance on a 3G! My other part of the app involves zooming in to some images by scaling up the images, switching images by push or dissolve upon receiving touch events, saving photos into photo library and storing and retrieving some photos in a folder and some data in a SQlite database, each showing un-smooth actions. Compared with some heavy graphic or heavy maths app, I think mine is pretty simple. I totally have no clue why the app would behave so slow and un-smooth that it is barely useful on a 3G. Any help/ direction would be much appreciated. Thanks for helping out.

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  • Call .NET Webservice with Android

    - by Lasse P
    Hi, I know this question has been asked here before, but I don't think those answers were adequate for my needs. We have a SOAP webservice that is used for an iPhone application, but it is possible that we need an Android specific version or a proxy of the service, so we have the option to go with either SOAP or JSON. I have a few concerns about both methods: SOAP solution: Is it possible to generate java source code from a WSDL file, if so, will it include some kind of proxy class to invoke the webservice and will it work in the Android environment at all? Google has not provided any SOAP library in Android, so i need to use 3rd party, any suggestion? What about the performance/overhead with parsing and transmitting SOAP xml over the wire versus the JSON solution? JSON solution: There is a few classes in the Android sdk that will let me parse JSON, but does it support generic parsing, like if I want the result to be parsed as a complex type? Or would I need to implement that myself? I have read about 2 libraries before here on Stackoverflow, GSON an Jackson. What is the difference performance and usability (from a developers perspective) wise? Do you guys have any experince with either of those libraries? So i guess the big question is, what method to go with? I hope you can help me out. Thanks in advance :-)

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  • Why does PEAR get installed to my user directory?

    - by webworm
    I am new to Linux and I am attempting to install the PHP PEAR library on a virtual server which is running Ubuntu. I am following a tutorial that covers installing PEAR but have run up against an area where I am confused. When running the PEAR installation program I am prompted as to what I want the INSTALL_PREFIX to be. Evidently the INSTALL_PREFIX, among other things, determines where PEAR will be installed. The tutorial suggest the value of INSTALL_PREFIX be the following path ... "/home/MY_USER_NAME/pear" where MY_USER_NAME = my user account Having come from a Windows world, applications are installed on the system where everyone can use them. If I install PEAR underneath my user directory will other developers on the system be able to make use of PEAR in their PHP scripts? I want to make PEAR available to all users and not just myself. Could someone explain to me the difference between installing for all users and installing just for myself? Does the install location matter? Should I be installing PEAR in a different location? Thanks for any suggestions. P.S. The tutorial I am following is located at the following URL ... http://articles.sitepoint.com/article/getting-started-with-pear/2

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  • Does F# documentation have a way to search for functions by their types?

    - by Nathan Sanders
    Say I want to know if F# has a library function of type ('T -> bool) -> 'T list -> int ie, something that counts how many items of a list that a function returns true for. (or returns the index of the first item that returns true) I used to use the big list at the MSR site for F# before the documentation on MSDN was ready. I could just search the page for the above text because the types were listed. But now the MSDN documentation only lists types on the individual pages--the module page is a mush of descriptive text. Google kinda-sorta works, but it can't help with // compatible interfaces ('T -> bool) -> Seq<'T> -> int // argument-swaps Seq<'T> -> ('T -> bool) -> int // type-variable names ('a -> bool) -> Seq<'a> -> int // wrappers ('a -> bool) -> 'a list -> option<int> // uncurried versions ('T -> bool) * 'T list -> int // .NET generic syntax ('T -> bool) -> List<'T> -> int // methods List<'T> member : ('T -> bool) -> int Haskell has a standalone program for this called Hoogle. Does F# have an equivalent, like Fing or something?

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  • MAC : How to check if the file is still being copied in cpp?

    - by Peda Pola
    In my current project, we had a requirement to check if the file is still copying. We have already developed a library which will give us OS notification like file_added , file_removed , file_modified, file_renamed on a particular folder along with the corresponding file path. The problem here is that, lets say if you add 1 GB file, it is giving multiple notification such as file_added , file_modified, file_modified as the file is being copied. Now i decided to surpass these notifications by checking if the file is copying or not. Based on that i will ignore events. I have written below code which tells if the file is being copied or not which takes file path as input parameter. Details:- In Mac, while file is being copied the creation date is set as some date less than 1970. Once it is copied the date is set to current date. Am using this technique. Based on this am deciding that file is being copied. Problem:- when we copy file in the terminal it is failing. Please advice me any approach. bool isBeingCopied(const boost::filesystem::path &filePath) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; bool isBeingCopied = false; if([[[[NSFileManager defaultManager] attributesOfItemAtPath:[NSString stringWithUTF8String:filePath.string().c_str()] error:nil] fileCreationDate] timeIntervalSince1970] < 0) { isBeingCopied = true; } [pool release]; return isBeingCopied; }

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  • Appropriate uses of Monad `fail` vs. MonadPlus `mzero`

    - by jberryman
    This is a question that has come up several times for me in the design code, especially libraries. There seems to be some interest in it so I thought it might make a good community wiki. The fail method in Monad is considered by some to be a wart; a somewhat arbitrary addition to the class that does not come from the original category theory. But of course in the current state of things, many Monad types have logical and useful fail instances. The MonadPlus class is a sub-class of Monad that provides an mzero method which logically encapsulates the idea of failure in a monad. So a library designer who wants to write some monadic code that does some sort of failure handling can choose to make his code use the fail method in Monad or restrict his code to the MonadPlus class, just so that he can feel good about using mzero, even though he doesn't care about the monoidal combining mplus operation at all. Some discussions on this subject are in this wiki page about proposals to reform the MonadPlus class. So I guess I have one specific question: What monad instances, if any, have a natural fail method, but cannot be instances of MonadPlus because they have no logical implementation for mplus? But I'm mostly interested in a discussion about this subject. Thanks! EDIT: One final thought occured to me. I recently learned (even though it's right there in the docs for fail) that monadic "do" notation is desugared in such a way that pattern match failures, as in (x:xs) <- return [] call the monad's fail. It seems like the language designers must have been strongly influenced by the prospect of some automatic failure handling built in to haskell's syntax in their inclusion of fail in Monad.

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  • Testing When Correctness is Poorly Defined?

    - by dsimcha
    I generally try to use unit tests for any code that has easily defined correct behavior given some reasonably small, well-defined set of inputs. This works quite well for catching bugs, and I do it all the time in my personal library of generic functions. However, a lot of the code I write is data mining code that basically looks for significant patterns in large datasets. Correct behavior in this case is often not well defined and depends on a lot of different inputs in ways that are not easy for a human to predict (i.e. the math can't reasonably be done by hand, which is why I'm using a computer to solve the problem in the first place). These inputs can be very complex, to the point where coming up with a reasonable test case is near impossible. Identifying the edge cases that are worth testing is extremely difficult. Sometimes the algorithm isn't even deterministic. Usually, I do the best I can by using asserts for sanity checks and creating a small toy test case with a known pattern and informally seeing if the answer at least "looks reasonable", without it necessarily being objectively correct. Is there any better way to test these kinds of cases?

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  • Setting up isolated COM for multiple projects.

    - by Praneeth
    My solution consists of multiple projects all of which out type class library except one whose output type is windows application. The application references all the other projects. I also have a COM component which is referenced by some of the projects and the application also. I can setup the regfree COM by changing the Isolated property of the referenced COM component in visual studio to TRUE. The solution builds successfully and I can see the manifest file generated for that particular assembly or application. Now, my question is that do I need to do this for all the projects which reference the COM component? If yes, then I know that i cannot set the Isolated property to TRUE on more than one project(gives a build error) so how do I workaround this? I am relatively new to .net and don't know much regfree COM(i assume what i am doing IS regfree COM?). Any help I can get on this issue is greatly appreciated. Thanks. I am currently using VS 2008.

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