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  • Testing complex compositions

    - by phlipsy
    I have a rather large collection of classes which check and mutate a given data structure. They can be composed via the composition pattern into arbitrarily complex tree-like structures. The final product contains a lot of these composed structures. My question is now: How can I test those? Albeit it is easy to test every single unit of these compositions, it is rather expensive to test the whole compositions in the following sense: Testing the correct layout of the composition-tree results in a huge number of test cases Changes in the compositions result in a very laborious review of every single test case What is the general guideline here?

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  • Combining template method with strategy

    - by Mekswoll
    An assignment in my software engineering class is to design an application which can play different forms a particular game. The game in question is Mancala, some of these games are called Wari or Kalah. These games differ in some aspects but for my question it's only important to know that the games could differ in the following: The way in which the result of a move is handled The way in which the end of the game is determined The way in which the winner is determined The first thing that came to my mind to design this was to use the strategy pattern, I have a variation in algorithms (the actual rules of the game). The design could look like this: I then thought to myself that in the game of Mancala and Wari the way the winner is determined is exactly the same and the code would be duplicated. I don't think this is by definition a violation of the 'one rule, one place' or DRY principle seeing as a change in rules for Mancala wouldn't automatically mean that rule should be changed in Wari as well. Nevertheless from the feedback I got from my professor I got the impression to find a different design. I then came up with this: Each game (Mancala, Wari, Kalah, ...) would just have attribute of the type of each rule's interface, i.e. WinnerDeterminer and if there's a Mancala 2.0 version which is the same as Mancala 1.0 except for how the winner is determined it can just use the Mancala versions. I think the implementation of these rules as a strategy pattern is certainly valid. But the real problem comes when I want to design it further. In reading about the template method pattern I immediately thought it could be applied to this problem. The actions that are done when a user makes a move are always the same, and in the same order, namely: deposit stones in holes (this is the same for all games, so would be implemented in the template method itself) determine the result of the move determine if the game has finished because of the previous move if the game has finished, determine who has won Those three last steps are all in my strategy pattern described above. I'm having a lot of trouble combining these two. One possible solution I found would be to abandon the strategy pattern and do the following: I don't really see the design difference between the strategy pattern and this? But I am certain I need to use a template method (although I was just as sure about having to use a strategy pattern). I also can't determine who would be responsible for creating the TurnTemplate object, whereas with the strategy pattern I feel I have families of objects (the three rules) which I could easily create using an abstract factory pattern. I would then have a MancalaRuleFactory, WariRuleFactory, etc. and they would create the correct instances of the rules and hand me back a RuleSet object. Let's say that I use the strategy + abstract factory pattern and I have a RuleSet object which has algorithms for the three rules in it. The only way I feel I can still use the template method pattern with this is to pass this RuleSet object to my TurnTemplate. The 'problem' that then surfaces is that I would never need my concrete implementations of the TurnTemplate, these classes would become obsolete. In my protected methods in the TurnTemplate I could just call ruleSet.determineWinner(). As a consequence, the TurnTemplate class would no longer be abstract but would have to become concrete, is it then still a template method pattern? To summarize, am I thinking in the right way or am I missing something easy? If I'm on the right track, how do I combine a strategy pattern and a template method pattern? This is part of a homework assignment but I'm not looking to be gifted the answer, I have deliberately been very verbose in my question to show that I have thought about it before coming here to ask a question

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  • [EF + Oracle] Entities

    - by JTorrecilla
    Prologue Following with the Serie I started yesterday about Entity Framework with Oracle, Today I am going to start talking about Entities. What is an Entity? A Entity is an object of the EF model corresponding to a record in a DB table. For example, let’s see, in Image 1 we can see one Entity from our model, and in the second one we can see the mapping done with the DB. (Image 1) (Image 2) More in depth a Entity is a Class inherited from the abstract class “EntityObject”, contained by the “System.Data.Objects.DataClasses” namespace. At the same time, this class inherits from the following Class and interfaces: StructuralObject: It is an Abstract class that inherits from INotifyPropertyChanging and INotifyPropertyChanged interfaces, and it exposes the events that manage the Changes of the class, and the functions related to check the data types of the Properties from our Entity.  IEntityWithKey: Interface which exposes the Key of the entity. IEntityWithChangeTracker: Interface which lets indicate the state of the entity (Detached, Modified, Added…) IEntityWithRelationships: Interface which indicates the relations about the entity. Which is the Content of a Entity? A Entity is composed by: Properties, Navigation Properties and Methods. What is a Property? A Entity Property is an object that represents a column from the mapped table from DB. It has a data type equivalent in .Net Framework to the DB Type. When we create the EF model, VS, internally, create the code for each Entity selected in the Tables step, such all methods that we will see in next steps. For each property, VS creates a structure similar to: · Private variable with the mapped Data type. · Function with a name like On{Property_Name}Changing({dataType} value): It manages the event which happens when we try to change the value. · Function with a name like On{Property_Name}Change: It manages the event raised when the property has changed successfully. · Property with Get and Set methods: The Set Method manages the private variable and do the following steps: Raise Changing event. Report the Entity is Changing. Set the prívate variable. For it, Use the SetValidValue function of the StructuralObject. There is a function for each datatype, and the functions takes 2 params: the value, and if the prop allow nulls. Invoke that the entity has been successfully changed. Invoke the Changed event of the Prop. ReportPropertyChanging and ReportPropertyChanged events, let, respectively, indicate that there is pending changes in the Entity, and the changes have success correctly. While the ReportPropertyChanged is raised, the Track State of the Entity will be changed. What is a Navigation Property? Navigation Properties are a kind of property of the type: EntityCollection<TEntity>, where TEntity is an Entity type from the model related with the current one, it is said, is a set of record from a related table in the DB. The EntityCollection class inherits from: · RelatedEnd: There is an abstract class that give the functions needed to obtein the related objects. · ICollection<TEntity> · IEnumerable<TEntity> · IEnumerable · IListSource For the previous interfaces, I wish recommend the following post from Jose Miguel Torres. Navigation properties allow us, to get and query easily objects related with the Entity. Methods? There is only one method in the Entity object. “Create{Entity}”, that allow us to create an object of the Entity by sending the parameters needed to create it. Finally After this chapter, we know what is an Entity, how is related to the DB and the relation to other Entities. In following chapters, we will se CRUD operations(Create, Read, Update, Delete).

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  • Java Dragging an object from one area to another [on hold]

    - by user50369
    Hello I have a game where you drag bits of food around the screen. I want to be able to click on an ingredient and drag it to another part of the screen where I release the mouse. I am new to java so I do not really know how to do this please help me Here is me code. This is the class with the mouse listeners in it: public void mousePressed(MouseEvent e) { if (e.getButton() == MouseEvent.BUTTON1) { Comp.ml = true; // placing if (manager.title == true) { if (title.r.contains(Comp.mx, Comp.my)) { title.overview = true; } else if (title.r1.contains(Comp.mx, Comp.my)) { title.options = true; } else if (title.r2.contains(Comp.mx, Comp.my)) { System.exit(0); } } if (manager.option == true) { optionsMouse(e); } mouseinventory(e); } else if (e.getButton() == MouseEvent.BUTTON3) { Comp.mr = true; } } private void mouseinventory(MouseEvent e) { if (e.getButton() == MouseEvent.BUTTON1) { } else if (e.getButton() == MouseEvent.BUTTON1) { } } @Override public void mouseReleased(MouseEvent e) { if (e.getButton() == MouseEvent.BUTTON1) { Comp.ml = false; } else if (e.getButton() == MouseEvent.BUTTON3) { Comp.mr = false; } } @Override public void mouseDragged(MouseEvent e) { for(int i = 0; i < overview.im.ing.toArray().length; i ++){ if(overview.im.ing.get(i).r.contains(Comp.mx,Comp.my)){ overview.im.ing.get(i).newx = Comp.mx; overview.im.ing.get(i).newy = Comp.my; overview.im.ing.get(i).dragged = true; }else{ overview.im.ing.get(i).dragged = false; } } } @Override public void mouseMoved(MouseEvent e) { Comp.mx = e.getX(); Comp.my = e.getY(); // System.out.println("" + Comp.my); } This is the class called ingredient public abstract class Ingrediant { public int x,y,id,lastx,lasty,newx,newy; public boolean removed = false,dragged = false; public int width; public int height; public Rectangle r = new Rectangle(x,y,width,height); public Ingrediant(){ r = new Rectangle(x,y,width,height); } public abstract void tick(); public abstract void render(Graphics g); } and this is a class which extends ingredient called hagleave public class HagLeave extends Ingrediant { private Image img; public HagLeave(int x, int y, int id) { this.x = x; this.y = y; this.newx = x; this.newy = y; this.id = id; width = 75; height = 75; r = new Rectangle(x,y,width,height); } public void tick() { r = new Rectangle(x,y,width,height); if(!dragged){ x = newx; y = newy; } } public void render(Graphics g) { ImageIcon i2 = new ImageIcon("res/ingrediants/hagleave.png"); img = i2.getImage(); g.drawImage(img, x, y, null); g.setColor(Color.red); g.drawRect(r.x, r.y, r.width, r.height); } } The arraylist is in a class called ingrediantManager: public class IngrediantsManager { public ArrayList<Ingrediant> ing = new ArrayList<Ingrediant>(); public IngrediantsManager(){ ing.add(new HagLeave(100,200,1)); ing.add(new PigHair(70,300,2)); ing.add(new GiantsToe(100,400,3)); } public void tick(){ for(int i = 0; i < ing.toArray().length; i ++){ ing.get(i).tick(); if(ing.get(i).removed){ ing.remove(i); i--; } } } public void render(Graphics g){ for(int i = 0; i < ing.toArray().length; i ++){ ing.get(i).render(g); } } }

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  • How do I improve my incremental-backup performance?

    - by Alistair Bell
    I'm currently using the traditional rsync+cp -al method to create incremental/snapshot backups of our server tree. The backups are going onto a pair of eight-disk towers connected to the backup machine (a Sandy Bridge machine with 16 GB of RAM, running CentOS 5.5) via four eSATA connections (four disks per connection). Each disk is a regular 2 TB disk, so we have 32 TB of disk space connected to the backup machine. We're backing up about 20 TB of data on the servers with this. The problem is that each daily backup is taking more than 24 hours, and the real time-killer isn't the actual rsync, but the time it takes to perform a cp -al of the tree locally on the backup machine. It's taking more than 12 hours just to make the shadow copy of the tree, and as far as I can tell the performance backlog is at the disk (top shows the cp using a lot of RAM but not a lot of CPU and mostly in uninterruptible-sleep state) We have the server data split into four major volumes (and a few minor ones), and each of these backups runs in parallel (with some offsets in the cron to try to get some disks' cp done first). There are two volumes on the backup drive, both striped LVM volumes of 16 TB each. So obviously I need to improve the performance because it's unusable as it stands. The first question is: when CentOS 6 comes out, with support for btrfs, will making snapshots of subvolumes with btrfs substantially increase this performance? The second is: is there a way, with ext3 or something else supported in CentOS 5 or 6, to 'encourage' it to put the directories/inodes in one part of a volume (which could happen to be the part that's on an SSD, via LVM) and the files in another? That would presumably solve the problem, but I don't know of ways to hint ext3 like that.

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  • Setup of HP ProCurve 2810-24G for iSCSI?

    - by 3molo
    Hi, I have a pair of ProCurve 2810-24G that I will use with a Dell Equallogic SAN and Vmware ESXi. Since ESXi does MPIO, I am a little uncertain on the configuration for links between the switches. Is a trunk the right way to go between the switches? I know that the ports for the SAN and the ESXi hosts should be untagged, so does that mean that I want tagged VLAN on the trunk ports? This is more or less the configuration: trunk 1-4 Trk1 Trunk snmp-server community "public" Unrestricted vlan 1 name "DEFAULT_VLAN" untagged 24,Trk1 ip address 10.180.3.1 255.255.255.0 no untagged 5-23 exit vlan 801 name "Storage" untagged 5-23 tagged Trk1 jumbo exit no fault-finder broadcast-storm stack commander "sanstack" spanning-tree spanning-tree Trk1 priority 4 spanning-tree force-version RSTP-operation The Equallogic PS4000 SAN has two controllers, with two network interfaces each. Dell recommends each controller to be connected to each of the switches. From vmware documentation, it seems creating one vmkernel per pNIC is recommended. With MPIO, this could allow for more than 1 Gbps throughput.

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  • Updating PHP on Linux - "No Packages marked for Update"?

    - by Aristotle
    I'm very new to server-administration, but I was thinking the task of updating PHP to 5.2+ should be relatively simple. Online I found that the following was allegedly sufficient to do this: yum update php But when I run this, the following is output: [root@ip-XXX-XXX-XXX-XXX /]# php -v PHP 5.1.6 (cli) (built: Jan 13 2010 17:13:05) Copyright (c) 1997-2006 The PHP Group Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies [root@ip-XXX-XXX-XXX-XXX /]# yum update php Loaded plugins: fastestmirror Determining fastest mirrors * addons: p3plmirror02.prod.phx3.secureserver.net * base: p3plmirror02.prod.phx3.secureserver.net * extras: p3plmirror02.prod.phx3.secureserver.net * turbopanel-base: p3plmirror02.prod.phx3.secureserver.net * turbopanel-centos5: p3plmirror02.prod.phx3.secureserver.net * update: p3plmirror02.prod.phx3.secureserver.net addons | 951 B 00:00 addons/primary | 201 B 00:00 base | 2.1 kB 00:00 base/primary_db | 1.6 MB 00:00 extras | 1.1 kB 00:00 extras/primary | 107 kB 00:00 extras 325/325 turbopanel-base | 951 B 00:00 turbopanel-base/primary | 72 kB 00:00 turbopanel-base 494/494 turbopanel-centos5 | 951 B 00:00 turbopanel-centos5/primary | 2.1 kB 00:00 turbopanel-centos5 8/8 update | 1.9 kB 00:00 update/primary_db | 463 kB 00:00 Setting up Update Process No Packages marked for Update [root@ip-XXX-XXX-XXX-XXX /]# php -v PHP 5.1.6 (cli) (built: Jan 13 2010 17:13:05) Copyright (c) 1997-2006 The PHP Group Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technolog [root@ip-XXX-XXX-XXX-XXX /]# No Packages marked for Update [root@ip-XXX-XXX-XXX-XXX /]# php -v bash: No: command not found [root@ip-XXX-XXX-XXX-XXX /]# [root@ip-XXX-XXX-XXX-XXX /]# php -v bash: [root@ip-XXX-XXX-XXX-XXX: command not found [root@ip-XXX-XXX-XXX-XXX /]# PHP 5.1.6 (cli) (built: Jan 13 2010 17:13:05) bash: syntax error near unexpected token `(' [root@ip-XXX-XXX-XXX-XXX /]# Copyright (c) 1997-2006 The PHP Group bash: syntax error near unexpected token `c' [root@ip-XXX-XXX-XXX-XXX /]# Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies bash: syntax error near unexpected token `(' [root@ip-XXX-XXX-XXX-XXX /]# My PHP version is 5.1.6 before, and after running the command. Am I being too naive here with this update process? Is there a more verbose route that is necessary for me to take?

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  • Can't install xclip on Ubuntu 10.10

    - by wildster
    I'm trying to load an SSH key to Github from a new machine and this command is not working: sudo apt-get install xclip Reading package lists... Done Building dependency tree Reading state information... Done Package xclip is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package xclip has no installation candidate when I try: sudo aptitude install xclip Reading package lists... Done Building dependency tree Reading state information... Done Reading extended state information Initializing package states... Done No candidate version found for xclip No candidate version found for xclip The following partially installed packages will be configured: synaptics-dkms 0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Need to get 0B of archives. After unpacking 0B will be used. Writing extended state information... Done Setting up synaptics-dkms (1.1.1) ... Loading new synaptics-1.1.1 DKMS files... Error! Cannot locate /usr/src/synaptics-1.1.1.dkms.tar.gz. File does not exist. dpkg: error processing synaptics-dkms (--configure): subprocess installed post-installation script returned error exit status 2 Errors were encountered while processing: synaptics-dkms E: Sub-process /usr/bin/dpkg returned an error code (1) A package failed to install. Trying to recover: Setting up synaptics-dkms (1.1.1) ... Loading new synaptics-1.1.1 DKMS files... Error! Cannot locate /usr/src/synaptics-1.1.1.dkms.tar.gz. File does not exist. dpkg: error processing synaptics-dkms (--configure): subprocess installed post-installation script returned error exit status 2 Errors were encountered while processing: synaptics-dkms Reading package lists... Done Building dependency tree Reading state information... Done Reading extended state information Initializing package states... Done Any idea how I can install this? Mucho thanks in advance

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  • Can't install xclip on Ubuntu 10.10

    - by wildster
    I'm trying to load an SSH key to Github from a new machine and this command is not working: sudo apt-get install xclip Reading package lists... Done Building dependency tree Reading state information... Done Package xclip is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source E: Package xclip has no installation candidate when I try: sudo aptitude install xclip Reading package lists... Done Building dependency tree Reading state information... Done Reading extended state information Initializing package states... Done No candidate version found for xclip No candidate version found for xclip The following partially installed packages will be configured: synaptics-dkms 0 packages upgraded, 0 newly installed, 0 to remove and 0 not upgraded. Need to get 0B of archives. After unpacking 0B will be used. Writing extended state information... Done Setting up synaptics-dkms (1.1.1) ... Loading new synaptics-1.1.1 DKMS files... Error! Cannot locate /usr/src/synaptics-1.1.1.dkms.tar.gz. File does not exist. dpkg: error processing synaptics-dkms (--configure): subprocess installed post-installation script returned error exit status 2 Errors were encountered while processing: synaptics-dkms E: Sub-process /usr/bin/dpkg returned an error code (1) A package failed to install. Trying to recover: Setting up synaptics-dkms (1.1.1) ... Loading new synaptics-1.1.1 DKMS files... Error! Cannot locate /usr/src/synaptics-1.1.1.dkms.tar.gz. File does not exist. dpkg: error processing synaptics-dkms (--configure): subprocess installed post-installation script returned error exit status 2 Errors were encountered while processing: synaptics-dkms Reading package lists... Done Building dependency tree Reading state information... Done Reading extended state information Initializing package states... Done Any idea how I can install this? Mucho thanks in advance

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  • GitHub - commit local changes in local branch to remote branch

    - by user62046
    I use Git Shell in Windows 7, working in a branch named Save-Rotation. Then I used git push origin Save-Rotation to commit the changes to remote. The result is posted at the end. It seems good. But when I went to my repository in GitHub site, which is https://github.com/chiapas/sumatrapdf/tree/Save-Rotation I can't see any change in the repository tree or commit tree. How can I know if the commit (to remote) is successful, and why the repository page is not updated? Here is the result in command-line C:\Users\imo\Documents\GitHub\sumatrapdf [Save-Rotation]> git push origin Save-R otation Counting objects: 167, done. Delta compression using up to 8 threads. Compressing objects: 100% (18/18), done. Writing objects: 100% (119/119), 27.43 KiB, done. Total 119 (delta 101), reused 119 (delta 101) To https://github.com/chiapas/sumatrapdf * [new branch] Save-Rotation -> Save-Rotation C:\Users\imo\Documents\GitHub\sumatrapdf [Save-Rotation +2 ~17 -0 !]> git push o rigin Save-Rotation Everything up-to-date C:\Users\imo\Documents\GitHub\sumatrapdf [Save-Rotation +2 ~17 -0 !]>

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  • Is there any functional-like unix shell?

    - by Caruccio
    I'm (really) newbie to functional programming (in fact only had contact with it using python) but seems to be a good approach for some list-intensive tasks in a shell environment. I'd love to do something like this: $ [ git clone $host/$repo for repo in repo1 repo2 repo3 ] Is there any Unix shell with these kind of feature? Or maybe some feature to allow easy shell access (commands, env/vars, readline, etc...) from within python (the idea is to use python's interactive interpreter as a replacement to bash). EDIT: Maybe a comparative example would clarify. Let's say I have a list composed of dir/file: $ FILES=( build/project.rpm build/project.src.rpm ) And I want to do a really simple task: copy all files to dist/ AND install it in the system (it's part of a build process): Using bash: $ cp ${files[*]} dist/ $ cd dist && rpm -Uvh $(for f in ${files[*]}; do basename $f; done)) Using a "pythonic shell" approach (caution: this is imaginary code): $ cp [ os.path.join('dist', os.path.basename(file)) for file in FILES ] 'dist' Can you see the difference ? THAT is what i'm talking about. How can not exits a shell with these kind of stuff build-in yet? It's a real pain to handle lists in shell, even its being a so common task: list of files, list of PIDs, list of everything. And a really, really, important point: using syntax/tools/features everybody already knows: sh and python. IPython seams to be on a good direction, but it's bloated: if var name starts with '$', it does this, if '$$' it does that. It's syntax is not "natural", so many rules and "workarounds" ([ ln.upper() for ln in !ls ] -- syntax error)

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  • LaTeX: Multiple authors in a two-column article

    - by Amro
    I'm kind of new to LaTeX and I am having a bit of a problem.. I am using a twocolumn layout for my article. There are four authors involved with different affiliations, and I am trying to list all of them under the title so they span the entire width of the page (all on the same level). It should be similar to this: Article Title auth1FN auth1LN 2 ... 3 auth4FN auth4LN department ... department school ... school email@edu ... email@edu Abstract ..................... .................... ..................... .................... ..................... .................... ..................... Currently I have something along the lines: \documentclass[10pt,twocolumn]{article} \usepackage{multicol} \begin{document} \begin{multicols}{2} \title{Article Title} \author{ First Last\\ Department\\ school\\ email@edu \and First Last\\ ... } \date{} \maketitle \end{multicols} \begin{abstract} ... \end{abstract} \section{Introduction} ... \end{document} The problem is that the authors are not displayed all on the same level, instead I get the first three next to each other, followed by the last one underneath. Is there way to achieve what I want? Also if possible, how can I customize the font of the affiliations (to be smaller and in italic)?

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  • Duplicate method 'ProcessRequest' in ASPX

    - by Mauricio Scheffer
    I'm trying to code ASP.NET MVC views (WebForms view engine) in F#. I can already write regular ASP.NET WebForms ASPX and it works ok, e.g. <%@ Page Language="F#" %> <% for i in 1..2 do %> <%=sprintf "%d" i %> so I assume I have everything in my web.config correctly set up. However, when I make the page inherit from ViewPage: <%@ Page Language="F#" Inherits="System.Web.Mvc.ViewPage" %> I get this error: Compiler Error Message: FS0442: Duplicate method. The abstract method 'ProcessRequest' has the same name and signature as an abstract method in an inherited type. The problem seems to be this piece of code generated by the F# CodeDom provider: [<System.Diagnostics.DebuggerNonUserCodeAttribute>] abstract ProcessRequest : System.Web.HttpContext -> unit [<System.Diagnostics.DebuggerNonUserCodeAttribute>] default this.ProcessRequest (context:System.Web.HttpContext) = let mutable context = context base.ProcessRequest(context) |> ignore when I change the Page directive to use C# instead, the generated code is: [System.Diagnostics.DebuggerNonUserCodeAttribute()] public new virtual void ProcessRequest(System.Web.HttpContext context) { base.ProcessRequest(context); } which of course works fine and AFAIK is not semantically the same as the generated F# code. I'm using .NET 4.0.30319.1 (RTM) and MVC 2 RTM

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  • Setting up DrJava to work through Friedman / Felleisen "A Little Java"

    - by JDelage
    All, I'm going through the Friedman & Felleisen book "A Little Java, A Few Patterns". I'm trying to type the examples in DrJava, but I'm getting some errors. I'm a beginner, so I might be making rookie mistakes. Here is what I have set-up: public class ALittleJava { //ABSTRACT CLASS POINT abstract class Point { abstract int distanceToO(); } class CartesianPt extends Point { int x; int y; int distanceToO(){ return((int)Math.sqrt(x*x+y*y)); } CartesianPt(int _x, int _y) { x=_x; y=_y; } } class ManhattanPt extends Point { int x; int y; int distanceToO(){ return(x+y); } ManhattanPt(int _x, int _y){ x=_x; y=_y; } } } And on the main's side: public class Main{ public static void main (String [] args){ Point y = new ManhattanPt(2,8); System.out.println(y.distanceToO()); } } The compiler cannot find the symbols Point and ManhattanPt in the program. If I precede each by ALittleJava., I get another error in the main, i.e., an enclosing instance that contains ALittleJava.ManhattanPt is required I've tried to find ressources on the 'net, but the book must have a pretty confidential following and I couldn't find much. Thank you all. JDelage

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  • How can I improve this design?

    - by klausbyskov
    Let's assume that our system can perform actions, and that an action requires some parameters to do its work. I have defined the following base class for all actions (simplified for your reading pleasure): public abstract class BaseBusinessAction<TActionParameters> : where TActionParameters : IActionParameters { protected BaseBusinessAction(TActionParameters actionParameters) { if (actionParameters == null) throw new ArgumentNullException("actionParameters"); this.Parameters = actionParameters; if (!ParametersAreValid()) throw new ArgumentException("Valid parameters must be supplied", "actionParameters"); } protected TActionParameters Parameters { get; private set; } protected abstract bool ParametersAreValid(); public void CommonMethod() { ... } } Only a concrete implementation of BaseBusinessAction knows how to validate that the parameters passed to it are valid, and therefore the ParametersAreValid is an abstract function. However, I want the base class constructor to enforce that the parameters passed are always valid, so I've added a call to ParametersAreValid to the constructor and I throw an exception when the function returns false. So far so good, right? Well, no. Code analysis is telling me to "not call overridable methods in constructors" which actually makes a lot of sense because when the base class's constructor is called the child class's constructor has not yet been called, and therefore the ParametersAreValid method may not have access to some critical member variable that the child class's constructor would set. So the question is this: How do I improve this design? Do I add a Func<bool, TActionParameters> parameter to the base class constructor? If I did: public class MyAction<MyParameters> { public MyAction(MyParameters actionParameters, bool something) : base(actionParameters, ValidateIt) { this.something = something; } private bool something; public static bool ValidateIt() { return something; } } This would work because ValidateIt is static, but I don't know... Is there a better way? Comments are very welcome.

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  • Factory Method Pattern clarification

    - by nettguy
    My understanding of Factory Method Pattern is (Correct me if i am wrong) Factory Method Pattern "Factory Method allow the client to delegates the product creation (Instance Creation) to the subclass". There are two situation in which we can go for creating Factory Method pattern. (i) When the client is restricted to the product (Instance) creation. (ii) There are multiple products available.But a decision to be made which product instance need to be returned. If you want to create Abstract Method pattern You need to have abstract product Concrete Product Factory Method to return the appropriate product. Example : public enum ORMChoice { L2SQL, EFM, LS, Sonic } //Abstract Product public interface IProduct { void ProductTaken(); } //Concrete Product public class LinqtoSql : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:LinqtoSql"); } } //concrete product public class Subsonic : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:Subsonic"); } } //concrete product public class EntityFramework : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken:EntityFramework"); } } //concrete product public class LightSpeed : IProduct { public void ProductTaken() { Console.WriteLine("OR Mapping Taken :LightSpeed"); } } public class Creator { //Factory Method public IProduct ReturnORTool(ORMChoice choice) { switch (choice) { case ORMChoice.EFM:return new EntityFramework(); break; case ORMChoice.L2SQL:return new LinqtoSql(); break; case ORMChoice.LS:return new LightSpeed(); break; case ORMChoice.Sonic:return new Subsonic(); break; default: return null; } } } **Client** Button_Click() { Creator c = new Creator(); IProduct p = c.ReturnORTool(ORMChoice.L2SQL); p.ProductTaken(); } Is my understanding of Factory Method is correct?

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  • Java method keyword "final" and its use

    - by Lukas Eder
    When I create complex type hierarchies (several levels, several types per level), I like to use the final keyword on methods implementing some interface declaration. An example: interface Garble { int zork(); } interface Gnarf extends Garble { /** * This is the same as calling {@link #zblah(0)} */ int zblah(); int zblah(int defaultZblah); } And then abstract class AbstractGarble implements Garble { @Override public final int zork() { ... } } abstract class AbstractGnarf extends AbstractGarble implements Gnarf { // Here I absolutely want to fix the default behaviour of zblah // No Gnarf shouldn't be allowed to set 1 as the default, for instance @Override public final int zblah() { return zblah(0); } // This method is not implemented here, but in a subclass @Override public abstract int zblah(int defaultZblah); } I do this for several reasons: It helps me develop the type hierarchy. When I add a class to the hierarchy, it is very clear, what methods I have to implement, and what methods I may not override (in case I forgot the details about the hierarchy) I think overriding concrete stuff is bad according to design principles and patterns, such as the template method pattern. I don't want other developers or my users do it. So the final keyword works perfectly for me. My question is: Why is it used so rarely in the wild? Can you show me some examples / reasons where final (in a similar case to mine) would be very bad?

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  • Dealing with multiple generics in a method call

    - by thaBadDawg
    I've been dealing a lot lately with abstract classes that use generics. This is all good and fine because I get a lot of utility out of these classes but now it's making for some rather ugly code down the line. For example: abstract class ClassBase<T> { T Property { get; set; } } class MyClass : ClassBase<string> { OtherClass PropertyDetail { get; set; } } This implementation isn't all that crazy, except when I want to reference the abstract class from a helper class and then I have to make a list of generics just to make reference to the implemented class, like this below. class Helper { void HelpMe<C, T>(object Value) where C : ClassBase<T>, new() { DoWork(); } } This is just a tame example, because I have some method calls where the list of where clauses end up being 5 or 6 lines long to handle all of the generic data. What I'd really like to do is class Helper { void HelpMe<C>(object Value) where C : ClassBase, new() { DoWork(); } } but it obviously won't compile. I want to reference ClassBase without having to pass it a whole array of generic classes to get the function to work, but I don't want to reference the higher level classes because there are a dozen of those. Am I the victim of my own cleverness or is there an avenue that I haven't considered yet?

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  • Can't get rails app to start on heroku

    - by jonnii
    I'm trying to deploy a rails app to heroku, but keep getting the following error. I'd have thought that managing the postgres gems would be something heroku would handle. I've tried everything I can think of short of installing postgres on my local machine, which I'd need to do if I wanted to install the postgres gem. There's also no gem called activerecord-postgresql-adapter... I'm guessing this is the standard adapter that comes with rails?? Any thoughts on how to fix this? App failed to start /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:76:in `establish_connection': Please install the postgresql adapter: `gem install activerecord-postgresql-adapter` (no such file to load -- pg) (RuntimeError) from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:60:in `establish_connection' from /usr/local/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_specification.rb:55:in `establish_connection' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:438:in `initialize_database' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:141:in `process' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `send' from /usr/local/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/initializer.rb:113:in `run' from /disk1/home/slugs/135415_c7f31f0_9f1f/mnt/config/environment.rb:9 from /usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' ... 14 levels... from /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/builder.rb:29:in `instance_eval' from /usr/local/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/builder.rb:29:in `initialize' from /home/heroku_rack/heroku.ru:1:in `new' from /home/heroku_rack/heroku.ru:1

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  • Retrieve values from multimdimensional array

    - by vincentlerry
    I have a great difficulty. I need to retrieve [title], [url] and [abstract] values ??from this multidimensional array. Also, I have to store those values in mysql database. thanks in advance!!! Array ( [bossresponse] = Array ( [responsecode] = 200 [limitedweb] = Array ( [start] = 0 [count] = 20 [totalresults] = 972000 [results] = Array ( [0] = Array ( [date] = [clickurl] = http://www.torchlake.com/ [url] = http://www.torchlake.com/ [dispurl] = www.torchlake.com [title] = Torch Lake, COLI Inc, Highspeed, Dial-up, Wireless ... [abstract] = Welcome to COLI Inc. Chain O' Lake Internet. Local Northern Michigan ISP, offering Dialup Internet access, Wireless access, Web design, and T1 services in Northern ... ) [1] = Array ( [date] = [clickurl] = http://en.wikipedia.org/wiki/Torch_Lake_(Antrim_County,_Michigan) [url] = http://en.wikipedia.org/wiki/Torch_Lake_(Antrim_County,_Michigan) [dispurl] = en.wikipedia.org/wiki/Torch_Lake_(Antrim_County,_Michigan) [title] = Torch Lake (Antrim County, Michigan) - Wikipedia, the free ... [abstract] = Torch Lake at 19 miles (31 km) long is Michigan's longest lake and at approximately 18,770 acres (76 km²) is Michigan's second largest lake. Within it are several ... ) this is the entire code that generates this array: require("OAuth.php"); $cc_key = ""; $cc_secret = ""; $url = "http://yboss.yahooapis.com/ysearch/limitedweb"; $args = array(); $args["q"] = "car"; $args["format"] = "json"; $args["count"] = 20; $consumer = new OAuthConsumer($cc_key, $cc_secret); $request = OAuthRequest::from_consumer_and_token($consumer, NULL,"GET", $url, $args); $request-sign_request(new OAuthSignatureMethod_HMAC_SHA1(), $consumer, NULL); $url = sprintf("%s?%s", $url, OAuthUtil::build_http_query($args)); $ch = curl_init(); $headers = array($request-to_header()); curl_setopt($ch, CURLOPT_HTTPHEADER, $headers); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE); $rsp = curl_exec($ch); $results = json_decode($rsp, true);

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  • Why am I getting this error when overriding an inherited method?

    - by Sergio Tapia
    Here's my parent class: public abstract class BaseFile { public string Name { get; set; } public string FileType { get; set; } public long Size { get; set; } public DateTime CreationDate { get; set; } public DateTime ModificationDate { get; set; } public abstract void GetFileInformation(); public abstract void GetThumbnail(); } And here's the class that's inheriting it: public class Picture:BaseFile { public override void GetFileInformation(string filePath) { FileInfo fileInformation = new FileInfo(filePath); if (fileInformation.Exists) { Name = fileInformation.Name; FileType = fileInformation.Extension; Size = fileInformation.Length; CreationDate = fileInformation.CreationTime; ModificationDate = fileInformation.LastWriteTime; } } public override void GetThumbnail() { } } I thought when a method was overridden, I could do what I wanted with it. Any help please? :)

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  • Problem with 2 levels of inheritance in hibernate mapping

    - by Seth
    Here's my class structure: class A class B extends A class C extends A class D extends C class E extends C And here are my mappings (class bodies omitted for brevity): Class A: @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @MappedSuperclass @DiscriminatorColumn( name="className", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class A Class B: @Entity @DiscriminatorValue("B") public class B extends A Class C: @Entity @DiscriminatorValue("C") @MappedSuperclass @DiscriminatorColumn( name="cType", discriminatorType=DiscriminatorType.STRING ) @ForceDiscriminator public abstract class C extends A Class D: @Entity @DiscriminatorValue("D") public class D extends C Class E: @Entity @DiscriminatorValue("E") public class E extends C I've got a class F that contains a set of A: @Entity public class F { ... @OneToMany(fetch=FetchType.LAZY, cascade=CascadeType.ALL) @JoinTable( name="F_A", joinColumns = @JoinColumn(name="A_ID"), inverseJoinColumns = @JoinColumn(name="F_ID") ) private Set<A> aSet = new HashSet<A>(); ... The problem is that whenever I add a new E instance to aSet and then call session.saveOrUpdate(fInstance), hibernate saves with "A" as the discrimiator string. When I try to access the aSet in the F instance, I get the following exception (full stacktrace ommitted for brevity): org.hibernate.InstantiationException: Cannot instantiate abstract class or interface: path.to.class.A Am I mapping the classes incorrectly? How am I supposed to map multiple levels of inheritance? Thanks for the help!

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  • Why doesn't the spring @Autowire work with java generics

    - by testing123
    Inspired by spring data awesomeness I wanted to create a abstract RESTController that I could extend for a lot of my controllers. I created the following class: @Controller public abstract class RESTController<E, PK extends Serializable, R extends PagingAndSortingRepository<E, PK>> { @Autowired private R repository; @RequestMapping(method=RequestMethod.GET, params={"id"}) @ResponseBody public E getEntity(@RequestParam PK id) { return repository.findOne(id); } ... } I was hoping that the generics would allow me to @Autowire in the repository but I get the following error: SEVERE: Allocate exception for servlet appServlet org.springframework.beans.factory.NoSuchBeanDefinitionException: No unique bean of type [org.springframework.data.repository.PagingAndSortingRepository] is defined: expected single matching bean but found 3: [groupRepository, externalCourseRepository, managedCourseRepository] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:800) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:707) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:478) at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:284) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1106) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456) at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294) I understand what the error is telling me, there is more than one match for the @Autowire. I am confused because I thought by creating the following controller it would work: @Controller @RequestMapping(value="/managedCourse") public class ManagedCourseController extends RESTController<ManagedCourse, Long, ManagedCourseRepository> { ... } This is easy enough to work around by doing having a method like this in the RESTController: protected abstract R getRepository(); and then doing this in your implementing class: @Autowired private ManagedCourseRepository repository; @Override protected ManagedCourseRepository getRepository() { return repository; } I was just wondering if someone had any thoughts of how I could get this to work.

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  • Reordering fields in Django model

    - by Alex Lebedev
    I want to add few fields to every model in my django application. This time it's created_at, updated_at and notes. Duplicating code for every of 20+ models seems dumb. So, I decided to use abstract base class which would add these fields. The problem is that fields inherited from abstract base class come first in the field list in admin. Declaring field order for every ModelAdmin class is not an option, it's even more duplicate code than with manual field declaration. In my final solution, I modified model constructor to reorder fields in _meta before creating new instance: class MyModel(models.Model): # Service fields notes = my_fields.NotesField() created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) class Meta: abstract = True last_fields = ("notes", "created_at", "updated_at") def __init__(self, *args, **kwargs): new_order = [f.name for f in self._meta.fields] for field in self.last_fields: new_order.remove(field) new_order.append(field) self._meta._field_name_cache.sort(key=lambda x: new_order.index(x.name)) super(TwangooModel, self).__init__(*args, **kwargs) class ModelA(MyModel): field1 = models.CharField() field2 = models.CharField() #etc ... It works as intended, but I'm wondering, is there a better way to acheive my goal?

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