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  • Lazy Sequences that "Look Ahead" for Project Euler Problem 14

    - by ivar
    I'm trying to solve Project Euler Problem 14 in a lazy way. Unfortunately, I may be trying to do the impossible: create a lazy sequence that is both lazy, yet also somehow 'looks ahead' for values it hasn't computed yet. The non-lazy version I wrote to test correctness was: (defn chain-length [num] (loop [len 1 n num] (cond (= n 1) len (odd? n) (recur (inc len) (+ 1 (* 3 n))) true (recur (inc len) (/ n 2))))) Which works, but is really slow. Of course I could memoize that: (def memoized-chain (memoize (fn [n] (cond (= n 1) 1 (odd? n) (+ 1 (memoized-chain (+ 1 (* 3 n)))) true (+ 1 (memoized-chain (/ n 2))))))) However, what I really wanted to do was scratch my itch for understanding the limits of lazy sequences, and write a function like this: (def lazy-chain (letfn [(chain [n] (lazy-seq (cons (if (odd? n) (+ 1 (nth lazy-chain (dec (+ 1 (* 3 n))))) (+ 1 (nth lazy-chain (dec (/ n 2))))) (chain (+ n 1)))))] (chain 1))) Pulling elements from this will cause a stack overflow for n2, which is understandable if you think about why it needs to look 'into the future' at n=3 to know the value of the tenth element in the lazy list because (+ 1 (* 3 n)) = 10. Since lazy lists have much less overhead than memoization, I would like to know if this kind of thing is possible somehow via even more delayed evaluation or queuing?

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  • Amazon EC2 Socket connection not being accepted

    - by Joseph
    I am trying to run a java application on my EC2 instance. The application accepts socket connections on port 54321. If I try and connect to it, it times out. My Security Group is set as: TCP Port (Service) Source Action 21 0.0.0.0/0 Delete 22 (SSH) 0.0.0.0/0 Delete 80 (HTTP) 0.0.0.0/0 Delete 20393 0.0.0.0/0 Delete 54321 0.0.0.0/0 Delete Is there anything else I need to do? # iptables -nvL Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination # iptables -nvL -t nat Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain INPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination #

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  • Why is my RapidSSL Certificate chain is not trusted on ubuntu?

    - by olouv
    I have a website that works perfectly with Chrome & other browser but i get some errors with PHP in CLI mode so i'm investigating it, running this: openssl s_client -showcerts -verify 32 -connect dev.carlipa-online.com:443 Quite suprisingly my HTTPS appears untrusted with a Verify return code: 27 (certificate not trusted) Here is the raw output : verify depth is 32 CONNECTED(00000003) depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA verify error:num=20:unable to get local issuer certificate verify return:1 depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA verify error:num=27:certificate not trusted verify return:1 depth=1 C = US, O = "GeoTrust, Inc.", CN = RapidSSL CA verify return:1 depth=0 serialNumber = khKDXfnS0WtB8DgV0CAdsmWrXl-Ia9wZ, C = FR, O = *.carlipa-online.com, OU = GT44535187, OU = See www.rapidssl.com/resources/cps (c)12, OU = Domain Control Validated - RapidSSL(R), CN = *.carlipa-online.com verify return:1 So GeoTrust Global CA appears to be not trusted on the system (Ubuntu 11.10). Added Equifax_Secure_CA to try to solve this... But i get in this case Verify return code: 19 (self signed certificate in certificate chain) ! Raw output : verify depth is 32 CONNECTED(00000003) depth=3 C = US, O = Equifax, OU = Equifax Secure Certificate Authority verify error:num=19:self signed certificate in certificate chain verify return:1 depth=3 C = US, O = Equifax, OU = Equifax Secure Certificate Authority verify return:1 depth=2 C = US, O = GeoTrust Inc., CN = GeoTrust Global CA verify return:1 depth=1 C = US, O = "GeoTrust, Inc.", CN = RapidSSL CA verify return:1 depth=0 serialNumber = khKDXfnS0WtB8DgV0CAdsmWrXl-Ia9wZ, C = FR, O = *.carlipa-online.com, OU = GT44535187, OU = See www.rapidssl.com/resources/cps (c)12, OU = Domain Control Validated - RapidSSL(R), CN = *.carlipa-online.com verify return:1 Edit Looks like my server does not trust/provide the Equifax Root CA, however i do correctly have the file in /usr/share/ca-certificates/mozilla/Equifax...

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  • JAX-WS modifying handler chain programmatically? PortInfo?

    - by wuntee
    I have a JAX-WS client that needs to have a modified handler-chain. I am currently doing it by binding this XML when generated the WSDL stubs: <jaxws:bindings xmlns:jaxws="http://java.sun.com/xml/ns/jaxws"> <jws:handler-chains xmlns:jws="http://java.sun.com/xml/ns/javaee"> <jws:handler-chain> <jws:handler> <jws:handler-name>ServiceRequestServiceClientHandler</jws:handler-name> <jws:handler-class>blah.ServiceRequestServiceClientHandler</jws:handler-class> </jws:handler> </jws:handler-chain> </jws:handler-chains> </jaxws:bindings> I was looking that the ServiceRequestService_Service object, and it seems like this could be done programmatically (easier in my opinion - less configuration files). new ServiceRequestService_Service().getHandlerResolver().getHandlerChain(PORTINFO).add(HANDLER); But, I do not know what the PortInfo object is, or how to obtain it in relation to the specific service. Has anyone done this?

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  • alias_attribute and creating and method with the original attribute name causes a loop

    - by Tiago
    Im trying to dynamically create a method chain in one attribute in my model. By now I have this function: def create_filtered_attribute(attribute_name) alias_attribute "#{attribute_name}_without_filter", attribute_name define_method "#{attribute_name}" do filter_words(self.send("#{attribute_name}_without_filter")) end end so I receive a string with the attribute name, alias it for '*_without_filter*' (alias_method or alias_method_chain fails here, because the attribute isnt there when the class is created), and I create a new method with the attribute name, where I filter its contents. But somehow, when I call *"#{attribute_name}_without_filter"* it calls my new method (i think because the alias_attribute some how), and the program goes into a stack loop. Can someone please enlighten me on this.

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  • Blend for Visual Studio 2013 Prototyping Applications with SketchFlow

    - by T
    Originally posted on: http://geekswithblogs.net/tburger/archive/2014/08/10/blend-for-visual-studio-2013-prototyping-applications-with-sketchflow.aspxSketchFlow enables rapid creating of dynamic interface mockups very quickly. The SketchFlow workspace is the same as the standard Blend workspace with the inclusion of three panels: the SketchFlow Feedback panel, the SketchFlow Animation panel and the SketchFlow Map panel. By using SketchFlow to prototype, you can get feedback early in the process. It helps to surface possible issues, lower development iterations, and increase stakeholder buy in. SketchFlow prototypes not only provide an initial look but also provide a way to add additional ideas and input and make sure the team is on track prior to investing in complete development. When you have completed the prototyping, you can discard the prototype and just use the lessons learned to design the application from or extract individual elements from your prototype and include them in the application. I don’t recommend trying to transition the entire project into a development project. Objects that you add with the SketchFlow style have a hand-sketched look. The sketch style is used to remind stakeholders that this is a prototype. This encourages them to focus on the flow and functionality without getting distracted by design details. The sketchflow assets are under sketchflow in the asset panel and are identifiable by the postfix “–Sketch”. For example “Button-Sketch”. You can mix sketch and standard controls in your interface, if required. Be creative, if there is a missing control or your interface has a different look and feel than the out of the box one, reuse other sketch controls to mimic the functionality or look and feel. Only use standard controls if it doesn’t distract from the idea that this is a prototype and not a standard application. The SketchFlow Map panel provides information about the structure of your application. To create a new screen in your prototype: Right-click the map surface and choose “Create a Connected Screen”. Name the screens with names that are meaningful to the stakeholders. The start screen is the one that has the green arrow. To change the start screen, right click on any other screen and set to start screen. Only one screen can be the start screen at a time. Rounded screen are component screens to mimic reusable custom controls that will be built into the final application. You can change the colors of all of the boxes and should use colors to create functional groupings. The groupings can be identified in the SketchFlow Project Settings. To add connections between screens in the SketchFlow Map panel. Move the mouse over a screen in the SketchFlow and a menu will appear at the bottom of the screen node. In the menu, click Connect to an existing screen. Drag the arrow to another screen on the Map. You add navigation to your prototype by adding connections on the SketchFlow map or by adding navigation directly to items on your interface. To add navigation from objects on the artboard, right click the item then from the menu, choose “Navigate to”. This will expose a sub-menu with available screens, backward, or forward. When the map has connected screens, the SketchFlow Player displays the connected screens on the Navigate sidebar. All screens show in the SketchFlow Player Map. To see the SketchFlow Player, run your SketchFlow prototype. The Navigation sidebar is meant to show the desired user work flow. The map can be used to view the different screens regardless of suggested navigation in the navigation bar. The map is able to be hidden and shown. As mentioned, a component screen is a shared screen that is used in more than one screen and generally represents what will be a custom object in the application. To create a component screen, you can create a screen, right click on it in the SketchFlow Map and choose “Make into component screen”. You can mouse over a screen and from the menu that appears underneath, choose create and insert component screen. To use an existing screen, select if from the Asset panel under SketchFlow, Components. You can use Storyboards and Visual State animations in your SketchFlow project. However, SketchFlow also offers its own animation technique that is simpler and better suited for prototyping. The SketchFlow Animation panel is above your artboard by default. In SketchFlow animation, you create frames and then position the elements on your interface for each frame. You then specify elapsed time and any effects you want to apply to the transition. The + at the top is what creates new frames. Once you have a new Frame, select it and change the property you want to animate. In the example above, I changed the Text of the result box. You can adjust the time between frames in the lower area between the frames. The easing and effects functions are changed in the center between each frame. You edit the hold time for frames by clicking the clock icon in the lower left and the hold time will appear on each frame and can be edited. The FluidLayout icon (also located in the lower left) will create smooth transitions. Next to the FluidLayout icon is the name of that Animation. You can rename the animation by clicking on it and editing the name. The down arrow chevrons next to the name allow you to view the list of all animations in this prototype and select them for editing. To add the animation to the interface object (such as a button to start the animation), select the PlaySketchFlowAnimationAction from the SketchFlow behaviors in the Assets menu and drag it to an object on your interface. With the PlaySketchFlowAnimationAction that you just added selected in the Objects and Timeline, edit the properties to change the EventName to the event you want and choose the SketchFlowAnimation you want from the drop down list. You may want to add additional information to your screens that isn’t really part of the prototype but is relevant information or a request for clarification or feedback from the reviewer. You do this with annotations or notes. Both appear on the user interface, however, annotations can be switched on or off at design and review time. Notes cannot be switched off. To add an Annotation, chose the Create Annotation from the Tools menu. The annotation appears on the UI where you will add the notes. To display or Hide annotations, click the annotation toggle at the bottom right on the artboard . After to toggle annotations on, the identifier of the person who created them appears on the artboard and you must click that to expand the notes. To add a note to the artboard, simply select the Note-Sketch from Assets ->SketchFlow ->Styles ->Sketch Styles. Drag and drop it to the artboard and place where you want it. When you are ready for users to review the prototype, you have a few options available. Click File -> Export and choose one of the options from the list: Publish to Sharepoint, Package SketchFlowProject, Export to Microsoft Word, or Export as Images. I suggest you play with as many of the options as you can to see what they do. Both the Sharepoint and Packaged SketchFlowProject allow you to collect feedback from one or more users that you can import into the project. The user can make notes on the UI and in the Feedback area in the bottom left corner of the player. When the user is done adding feedback, it is exported from the right most folder icon in the My Feedback panel. Feeback is imported on a panel named SketchFlow Feedback. To get that panel to show up, select Window -> SketchFlow Feedback. Once you have the panel showing, click the + in the upper right of the panel and find the notes you exported. When imported, they will show up in a list and on the artboard. To document your prototype, use the Export to Microsoft Word option from the File menu. That should get you started with prototyping.

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  • How to recover a file using the FAT cluster chain instead of using the stored length in the FAT table?

    - by cadrian
    I'm trying to recover movie files from my TNT receiver hard drive but it corrupts its FAT32 allocation table (crappy cheap device...) Using dosfsck is useless because the correct file length is the cluster length, not the (shorter) one in the table, and dosfsck only proposes to shorten the file, which I won't do. Question: how to recover a file using the FAT cluster chain instead of using the stored length in the FAT table? Edit I forgot to say: Linux solutions only please (I have no windows box)

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  • Is there a more intelligent way to do this besides a long chain of if statements or switch?

    - by Harrison Nguyen
    I'm implementing an IRC bot that receives a message and I'm checking that message to determine which functions to call. Is there a more clever way of doing this? It seems like it'd quickly get out of hand after I got up to like 20 commands. Perhaps there's a better way to abstract this? public void onMessage(String channel, String sender, String login, String hostname, String message){ if (message.equalsIgnoreCase(".np")){ // TODO: Use Last.fm API to find the now playing } else if (message.toLowerCase().startsWith(".register")) { cmd.registerLastNick(channel, sender, message); } else if (message.toLowerCase().startsWith("give us a countdown")) { cmd.countdown(channel, message); } else if (message.toLowerCase().startsWith("remember am routine")) { cmd.updateAmRoutine(channel, message, sender); } }

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  • Can I animate render targets or the swap chain?

    - by Eric F.
    I want to animate some synthetic video bits to fullscreen w/o tearing. Can I set up D3D 9/10/11 in exclusive mode, and have it present a series of buffers that I'm writing to? I know how to copy system memory bits into a texture, then draw that texture as a fullscreen quad, but it seems like overkill. Why should I use the triangle rasterizer when I want to do something so simple? All I want to do is set up a long (4-8 buffer) swapchain and set the bits of the back buffer that is about to be displayed. Or, I want to allocate 4-8 RenderTargets, and on each frame, copy the bits from system memory to the RenderTarget, then set it as the next thing to display. I've never seen or heard about anybody doing this, but it seems so dead simple!

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  • Can I copy a cross compiler tool chain between systems (I did before)?

    - by Jamie
    I tested fairly extensively with Ubuntu 10.04 Beta 2 Server in a VM, and was able to simply copy (read tar x) a cross compiled tool chain from an Ubuntu 8.10 VM. I created the tar myself, which is essentially a lot of stuff in \usr\local. Now that I've got a bare metal installation of Ubuntu 10.04 proper, the copy isn't working. In particularly, I'm getting the error: $ arm-linux-gcc -bash: /usr/local/bin/arm-linux-gcc: No such file or directory I've got the systems side by side in SSH windows ... any suggestions?

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  • Understanding and Implementing a Force based graph layout algorithm

    - by zcourts
    I'm trying to implement a force base graph layout algorithm, based on http://en.wikipedia.org/wiki/Force-based_algorithms_(graph_drawing) My first attempt didn't work so I looked at http://blog.ivank.net/force-based-graph-drawing-in-javascript.html and https://github.com/dhotson/springy I changed my implementation based on what I thought I understood from those two but I haven't managed to get it right and I'm hoping someone can help? JavaScript isn't my strong point so be gentle... If you're wondering why write my own. In reality I have no real reason to write my own I'm just trying to understand how the algorithm is implemented. Especially in my first link, that demo is brilliant. This is what I've come up with //support function.bind - https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Function/bind#Compatibility if (!Function.prototype.bind) { Function.prototype.bind = function (oThis) { if (typeof this !== "function") { // closest thing possible to the ECMAScript 5 internal IsCallable function throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable"); } var aArgs = Array.prototype.slice.call(arguments, 1), fToBind = this, fNOP = function () {}, fBound = function () { return fToBind.apply(this instanceof fNOP ? this : oThis || window, aArgs.concat(Array.prototype.slice.call(arguments))); }; fNOP.prototype = this.prototype; fBound.prototype = new fNOP(); return fBound; }; } (function() { var lastTime = 0; var vendors = ['ms', 'moz', 'webkit', 'o']; for(var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) { window.requestAnimationFrame = window[vendors[x]+'RequestAnimationFrame']; window.cancelAnimationFrame = window[vendors[x]+'CancelAnimationFrame'] || window[vendors[x]+'CancelRequestAnimationFrame']; } if (!window.requestAnimationFrame) window.requestAnimationFrame = function(callback, element) { var currTime = new Date().getTime(); var timeToCall = Math.max(0, 16 - (currTime - lastTime)); var id = window.setTimeout(function() { callback(currTime + timeToCall); }, timeToCall); lastTime = currTime + timeToCall; return id; }; if (!window.cancelAnimationFrame) window.cancelAnimationFrame = function(id) { clearTimeout(id); }; }()); function Graph(o){ this.options=o; this.vertices={}; this.edges={};//form {vertexID:{edgeID:edge}} } /** *Adds an edge to the graph. If the verticies in this edge are not already in the *graph then they are added */ Graph.prototype.addEdge=function(e){ //if vertex1 and vertex2 doesn't exist in this.vertices add them if(typeof(this.vertices[e.vertex1])==='undefined') this.vertices[e.vertex1]=new Vertex(e.vertex1); if(typeof(this.vertices[e.vertex2])==='undefined') this.vertices[e.vertex2]=new Vertex(e.vertex2); //add the edge if(typeof(this.edges[e.vertex1])==='undefined') this.edges[e.vertex1]={}; this.edges[e.vertex1][e.id]=e; } /** * Add a vertex to the graph. If a vertex with the same ID already exists then * the existing vertex's .data property is replaced with the @param v.data */ Graph.prototype.addVertex=function(v){ if(typeof(this.vertices[v.id])==='undefined') this.vertices[v.id]=v; else this.vertices[v.id].data=v.data; } function Vertex(id,data){ this.id=id; this.data=data?data:{}; //initialize to data.[x|y|z] or generate random number for each this.x = this.data.x?this.data.x:-100 + Math.random()*200; this.y = this.data.y?this.data.y:-100 + Math.random()*200; this.z = this.data.y?this.data.y:-100 + Math.random()*200; //set initial velocity to 0 this.velocity = new Point(0, 0, 0); this.mass=this.data.mass?this.data.mass:Math.random(); this.force=new Point(0,0,0); } function Edge(vertex1ID,vertex2ID){ vertex1ID=vertex1ID?vertex1ID:Math.random() vertex2ID=vertex2ID?vertex2ID:Math.random() this.id=vertex1ID+"->"+vertex2ID; this.vertex1=vertex1ID; this.vertex2=vertex2ID; } function Point(x, y, z) { this.x = x; this.y = y; this.z = z; } Point.prototype.plus=function(p){ this.x +=p.x this.y +=p.y this.z +=p.z } function ForceLayout(o){ this.repulsion = o.repulsion?o.repulsion:200; this.attraction = o.attraction?o.attraction:0.06; this.damping = o.damping?o.damping:0.9; this.graph = o.graph?o.graph:new Graph(); this.total_kinetic_energy =0; this.animationID=-1; } ForceLayout.prototype.draw=function(){ //vertex velocities initialized to (0,0,0) when a vertex is created //vertex positions initialized to random position when created cc=0; do{ this.total_kinetic_energy =0; //for each vertex for(var i in this.graph.vertices){ var thisNode=this.graph.vertices[i]; // running sum of total force on this particular node var netForce=new Point(0,0,0) //for each other node for(var j in this.graph.vertices){ if(thisNode!=this.graph.vertices[j]){ //net-force := net-force + Coulomb_repulsion( this_node, other_node ) netForce.plus(this.CoulombRepulsion( thisNode,this.graph.vertices[j])) } } //for each spring connected to this node for(var k in this.graph.edges[thisNode.id]){ //(this node, node its connected to) //pass id of this node and the node its connected to so hookesattraction //can update the force on both vertices and return that force to be //added to the net force this.HookesAttraction(thisNode.id, this.graph.edges[thisNode.id][k].vertex2 ) } // without damping, it moves forever // this_node.velocity := (this_node.velocity + timestep * net-force) * damping thisNode.velocity.x=(thisNode.velocity.x+thisNode.force.x)*this.damping; thisNode.velocity.y=(thisNode.velocity.y+thisNode.force.y)*this.damping; thisNode.velocity.z=(thisNode.velocity.z+thisNode.force.z)*this.damping; //this_node.position := this_node.position + timestep * this_node.velocity thisNode.x=thisNode.velocity.x; thisNode.y=thisNode.velocity.y; thisNode.z=thisNode.velocity.z; //normalize x,y,z??? //total_kinetic_energy := total_kinetic_energy + this_node.mass * (this_node.velocity)^2 this.total_kinetic_energy +=thisNode.mass*((thisNode.velocity.x+thisNode.velocity.y+thisNode.velocity.z)* (thisNode.velocity.x+thisNode.velocity.y+thisNode.velocity.z)) } cc+=1; }while(this.total_kinetic_energy >0.5) console.log(cc,this.total_kinetic_energy,this.graph) this.cancelAnimation(); } ForceLayout.prototype.HookesAttraction=function(v1ID,v2ID){ var a=this.graph.vertices[v1ID] var b=this.graph.vertices[v2ID] var force=new Point(this.attraction*(b.x - a.x),this.attraction*(b.y - a.y),this.attraction*(b.z - a.z)) // hook's attraction a.force.x += force.x; a.force.y += force.y; a.force.z += force.z; b.force.x += this.attraction*(a.x - b.x); b.force.y += this.attraction*(a.y - b.y); b.force.z += this.attraction*(a.z - b.z); return force; } ForceLayout.prototype.CoulombRepulsion=function(vertex1,vertex2){ //http://en.wikipedia.org/wiki/Coulomb's_law // distance squared = ((x1-x2)*(x1-x2)) + ((y1-y2)*(y1-y2)) + ((z1-z2)*(z1-z2)) var distanceSquared = ( (vertex1.x-vertex2.x)*(vertex1.x-vertex2.x)+ (vertex1.y-vertex2.y)*(vertex1.y-vertex2.y)+ (vertex1.z-vertex2.z)*(vertex1.z-vertex2.z) ); if(distanceSquared==0) distanceSquared = 0.001; var coul = this.repulsion / distanceSquared; return new Point(coul * (vertex1.x-vertex2.x),coul * (vertex1.y-vertex2.y), coul * (vertex1.z-vertex2.z)); } ForceLayout.prototype.animate=function(){ if(this.animating) this.animationID=requestAnimationFrame(this.animate.bind(this)); this.draw(); } ForceLayout.prototype.cancelAnimation=function(){ cancelAnimationFrame(this.animationID); this.animating=false; } ForceLayout.prototype.redraw=function(){ this.animating=true; this.animate(); } $(document).ready(function(){ var g= new Graph(); for(var i=0;i<=100;i++){ var v1=new Vertex(Math.random(), {}) var v2=new Vertex(Math.random(), {}) var e1= new Edge(v1.id,v2.id); g.addEdge(e1); } console.log(g); var l=new ForceLayout({ graph:g }); l.redraw(); });

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  • Ubuntu cannot access internet, LAN is fine

    - by Kevin Southworth
    I have an Ubuntu 8.04 LTS server that is directly connected to our Comcast Business Gateway modem and I have configured it with 1 of our 5 allotted Static IPs. My other machines on our LAN can connect to this server (via ssh, web, ping, etc.) but I cannot access this server from outside our network, and this machine cannot get out to the internet either (ping google.com fails with unknown host). Here is my /etc/networking/interfaces file: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 173.162.54.19 netmask 255.255.255.248 broadcast 173.162.54.23 gateway 173.162.54.22 and my /etc/resolv.conf: nameserver 68.87.77.130 nameserver 68.87.72.130 output from sudo route -n: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 173.162.54.16 0.0.0.0 255.255.255.248 U 0 0 0 eth0 0.0.0.0 173.162.54.22 0.0.0.0 UG 100 0 0 eth0 I have a Windows 2008 machine with an almost identical Static IP, static DNS setup and it works correctly, can access it within the LAN and also from public internet, the Windows machine and the Ubuntu machine are both directly connected to the Comcast Business Gateway. I have tried rebooting Ubuntu, rebooting my Comcast modem, but nothing seems to make it work. I'm an Ubuntu noob, is there some other config I need to apply to make this work? UPDATE: Yes I am able to ping my default gateway 173.162.54.22 output of iptables --list -n: Chain INPUT (policy DROP) target prot opt source destination ufw-before-input all -- 0.0.0.0/0 0.0.0.0/0 ufw-after-input all -- 0.0.0.0/0 0.0.0.0/0 Chain FORWARD (policy DROP) target prot opt source destination ufw-before-forward all -- 0.0.0.0/0 0.0.0.0/0 ufw-after-forward all -- 0.0.0.0/0 0.0.0.0/0 Chain OUTPUT (policy ACCEPT) target prot opt source destination ufw-before-output all -- 0.0.0.0/0 0.0.0.0/0 ufw-after-output all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-after-forward (1 references) target prot opt source destination LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK FORWARD]: ' RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-after-input (1 references) target prot opt source destination RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:137 RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:138 RETURN tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:139 RETURN tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:445 RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:67 RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:68 LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK INPUT]: ' RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-after-output (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-forward (1 references) target prot opt source destination ufw-user-forward all -- 0.0.0.0/0 0.0.0.0/0 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-input (1 references) target prot opt source destination ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED DROP all -- 0.0.0.0/0 0.0.0.0/0 ctstate INVALID ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 3 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 4 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 11 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 12 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 8 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:67 dpt:68 ufw-not-local all -- 0.0.0.0/0 0.0.0.0/0 ACCEPT all -- 224.0.0.0/4 0.0.0.0/0 ACCEPT all -- 0.0.0.0/0 224.0.0.0/4 ufw-user-input all -- 0.0.0.0/0 0.0.0.0/0 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-before-output (1 references) target prot opt source destination ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW,RELATED,ESTABLISHED ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW,RELATED,ESTABLISHED ufw-user-output all -- 0.0.0.0/0 0.0.0.0/0 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-not-local (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type LOCAL RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type MULTICAST RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type BROADCAST LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK NOT-TO-ME]: ' DROP all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-user-forward (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-user-input (1 references) target prot opt source destination ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:80 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:22 RETURN all -- 0.0.0.0/0 0.0.0.0/0 Chain ufw-user-output (1 references) target prot opt source destination RETURN all -- 0.0.0.0/0 0.0.0.0/0

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  • How to refresh a GridView?

    - by Daniel
    Hello everyone, I have a GridView which is pretty similar to the Google tutorial, except that I want to add the ImageViews on runtime (via a subactivity). The results are okay, but the layout of the View is messed up: The GridView doesn't fill the content of its parent, what do I have to do to design it properly? Here the code of adding the children: public void initializeWorkbench(GridView gv, Vector<String> items) { Prototype.workbench.setDimension(screenWidth, divider.height()+workbenchArea.height()); Prototype.workbench.activateWorkbench(); // this measures the workbench correctly Log.d(Prototype.TAG, "workbench width: "+Prototype.workbench.getMeasuredWidth()); // 320 Log.d(Prototype.TAG, "workbench height: "+Prototype.workbench.getMeasuredHeight()); // 30 ImageAdapter imgAdapter = new ImageAdapter(this.getContext(), items); gv.setAdapter(imgAdapter); gv.measure(screenWidth, screenHeight); gv.requestLayout(); gv.forceLayout(); Log.d(Prototype.TAG, "gv width: "+gv.getMeasuredWidth()); // 22 Log.d(Prototype.TAG, "gv height: "+gv.getMeasuredHeight()); // 119 Prototype.workbench.setDimension(screenWidth, divider.height()+workbenchArea.height()); } } activateWorkbench, setDimension and measure in the workbench (LinearLayout above the GridView): public void activateWorkbench() { if(this.equals(Prototype.workbench)) { this.setOrientation(VERTICAL); show = true; measure(); } } public void setDimension(int w, int h) { width = w; height = h; this.setLayoutParams(new LinearLayout.LayoutParams(width, height)); this.invalidate(); } private void measure() { if (this.getOrientation() == LinearLayout.VERTICAL) { int h = 0; int w = 0; this.measureChildren(0, 0); for (int i = 0; i < this.getChildCount(); i++) { View v = this.getChildAt(i); h += v.getMeasuredHeight(); w = (w < v.getMeasuredWidth()) ? v.getMeasuredWidth() : w; } if (this.equals(Prototype.tagarea)) height = (h < height) ? height : h; if (this.equals(Prototype.tagarea)) width = (w < width) ? width : w; } this.setMeasuredDimension(width, height); } The ImageAdapter constructor: public ImageAdapter(Context c, Vector<String> items) { mContext = c; boolean mExternalStorageAvailable = false; boolean mExternalStorageWriteable = false; String state = Environment.getExternalStorageState(); if (Environment.MEDIA_MOUNTED.equals(state)) { // We can read and write the media mExternalStorageAvailable = mExternalStorageWriteable = true; } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) { // We can only read the media mExternalStorageAvailable = true; mExternalStorageWriteable = false; } else { // Something else is wrong. It may be one of many other states, but // all we need // to know is we can neither read nor write mExternalStorageAvailable = mExternalStorageWriteable = false; } if (mExternalStorageAvailable && mExternalStorageWriteable) { for (String item : items) { File f = new File(item); if (f.exists()) { try { FileInputStream fis = new FileInputStream(f); Bitmap b = BitmapFactory.decodeStream(fis); bitmaps.add(b); files.add(f); } catch (FileNotFoundException e) { Log.e(Prototype.TAG, "", e); } } } } } And the xml layout: <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" android:gravity="bottom" android:paddingLeft="0px" android:paddingTop="0px" android:paddingRight="0px"> <com.unimelb.pt3.ui.TransparentPanel android:id="@+id/workbench" android:layout_width="fill_parent" android:layout_height="10px" android:paddingTop="0px" android:paddingLeft="0px" android:paddingBottom="0px" android:paddingRight="0px"> <GridView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/gridview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:columnWidth="90dp" android:numColumns="auto_fit" android:verticalSpacing="10dp" android:horizontalSpacing="10dp" android:stretchMode="columnWidth" android:gravity="center" /> </com.unimelb.pt3.ui.TransparentPanel> </LinearLayout>

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  • How to apply or chain multiple matching templates in XSLT?

    - by Ignatius
    I am working on a stylesheet employing many templates with match attributes: <xsl:template match="//one" priority="0.7"> <xsl:param name="input" select="."/> <xsl:value-of select="util:uppercase($input)"/> <xsl:next-match /> </xsl:template> <xsl:template match="/stuff/one"> <xsl:param name="input" select="."/> <xsl:value-of select="util:add-period($input)"/> </xsl:template> <xsl:function name="util:uppercase"> <xsl:param name="input"/> <xsl:value-of select="upper-case($input)"/> </xsl:function> <xsl:function name="util:add-period"> <xsl:param name="input"/> <xsl:value-of select="concat($input,'.')"/> </xsl:function> What I would like to do is be able to 'chain' the two functions above, so that an input of 'string' would be rendered in the output as 'STRING.' (with the period.) I would like to do this in such a way that doesn't require knowledge of other templates in any other template. So, for instance, I would like to be able to add a "util:add-colon" method without having to open up the hood and monkey with the existing templates. I was playing around with the <xsl:next-match/> instruction to accomplish this. Adding it to the first template above does of course invoke both util:uppercase and util:add-period, but the output is an aggregation of each template output (i.e. 'STRINGstring.') It seems like there should be an elegant way to chain any number of templates together using something like <xsl:next-match/>, but have the output of each template feed the input of the next one in the chain. Am I overlooking something obvious?

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  • Why can't I overwrite the prototype of `Array` (`Array.prototype`)?

    - by user828896
    I set the prototype of Array as an instance of my, I think book.aa will display "aa", but it displays "undefined", why? Thanks! <html> <head> <title>Array Properties</title> <h2>Array Properties</h2> <script type="text/javascript"> function my() { this.aa = 'aa'; } Array.prototype = new my(); Array.prototype.bb = "bb"; var book = new Array(); book[0] = "War and Peace"; </script> </head> <body bgcolor="lightblue"> <script type="text/javascript"> document.write(book.aa+book.bb); </script> </body> </html>

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  • Setting up WiFi extenders... is it possible to daisy-chain them?

    - by Bigbio2002
    At a location with limited cabling, I've had to set up WiFi signal extenders to cover the whole area. Here is a crude diagram... Internet - WiFi/Gateway - Extender 1 - Extender 2 | | PC (ethernet) WiFi device I was able to successfully daisy-chain three together, and I can access the internet from WiFi devices connected to the farthest extender. Is this a supported configuration? If not, what kind of issues can arise from it? The reason why I ask is that the PC keeps reporting IP address conflicts, and I'm wondering if that's caused because of the way this is configured. Additionally, I noticed that the extenders named their own SSID similar to the one they are connected to, but with a suffix. Would there be any issue in naming them all with the same SSID, to enable seamless roaming as you would with multiple standalone APs?

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  • Is there a suitable chain for iptables when eth is in Promisc mode?

    - by user1495181
    I have a fron-end machine. Machine have2 eth cards. I want to use netfilter queue to do some checks on the packets. I set eth like this: ifconfig eth0 0.0.0.0 promisc up ifconfig eth1 0.0.0.0 promisc up I want to have an iptable rule like this(only example): iptables -A INPUT -i eth0 -j LOG --log-prefix " eth0 packet " but the packet is no passed through the iptables ,because it dosnt target to this MAC. Promisc mode didnt help. I saw that there is a way to add iptables chain for PROMISC, but need compilation... Is there any simplier way to have iptables rule when packet is not target to this eth. Currently i bypass this by creating a bridge between 2 eth and put rule on the FORWARD, but i done want to create bridge.

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  • Inheritance of closure objects and overriding of methods

    - by bobikk
    I need to extend a class, which is encapsulated in a closure. This base class is following: var PageController = (function(){ // private static variable var _current_view; return function(request, new_view) { ... // priveleged public function, which has access to the _current_view this.execute = function() { alert("PageController::execute"); } } })(); Inheritance is realised using the following function: function extend(subClass, superClass){ var F = function(){ }; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; StartController.cache = ''; if (superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } I subclass the PageController: var StartController = function(request){ // calling the constructor of the super class StartController.superclass.constructor.call(this, request, 'start-view'); } // extending the objects extend(StartController, PageController); // overriding the PageController::execute StartController.prototype.execute = function() { alert('StartController::execute'); } Inheritance is working. I can call every PageController's method from StartController's instance. However, method overriding doesn't work: var startCont = new StartController(); startCont.execute(); alerts "PageController::execute". How should I override this method?

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  • Inereritance of clousure objects and overriding of methods

    - by bobikk
    I need to extend a class, which is encapsulated in a closure. This base class is following: var PageController = (function(){ // private static variable var _current_view; return function(request, new_view) { ... // priveleged public function, which has access to the _current_view this.execute = function() { alert("PageController::execute"); } } })();` Inheritance is realised using the following function: function extend(subClass, superClass){ var F = function(){ }; F.prototype = superClass.prototype; subClass.prototype = new F(); subClass.prototype.constructor = subClass; subClass.superclass = superClass.prototype; StartController.cache = ''; if (superClass.prototype.constructor == Object.prototype.constructor) { superClass.prototype.constructor = superClass; } } I subclass the PageController: var StartController = function(request){ // calling the constructor of the super class StartController.superclass.constructor.call(this, request, 'start-view'); } // extending the objects extend(StartController, PageController); // overriding the PageController::execute StartController.prototype.execute = function() { alert('StartController::execute'); } Inheritance is working. I can call every PageController's method from StartController's instance. However, method overriding doesn't work: var startCont = new StartController(); startCont.execute(); alerts "PageController::execute". How should I override this method?

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  • My Right-to-Left Foot (T-SQL Tuesday #13)

    - by smisner
    As a business intelligence consultant, I often encounter the situation described in this month's T-SQL Tuesday, hosted by Steve Jones ( Blog | Twitter) – “What the Business Says Is Not What the  Business Wants.” Steve posed the question, “What issues have you had in interacting with the business to get your job done?” My profession requires me to have one foot firmly planted in the technology world and the other foot planted in the business world. I learned long ago that the business never says exactly what the business wants because the business doesn't have the words to describe what the business wants accurately enough for IT. Not only do technological-savvy barriers exist, but there are also linguistic barriers between the two worlds. So how do I cope? The adage "a picture is worth a thousand words" is particularly helpful when I'm called in to help design a new business intelligence solution. Many of my students in BI classes have heard me explain ("rant") about left-to-right versus right-to-left design. To understand what I mean about these two design options, let's start with a picture: When we design a business intelligence solution that includes some sort of traditional data warehouse or data mart design, we typically place the data sources on the left, the new solution in the middle, and the users on the right. When I've been called in to help course-correct a failing BI project, I often find that IT has taken a left-to-right approach. They look at the data sources, decide how to model the BI solution as a _______ (fill in the blank with data warehouse, data mart, cube, etc.), and then build the new data structures and supporting infrastructure. (Sometimes, they actually do this without ever having talked to the business first.) Then, when they show what they've built to the business, the business says that is not what we want. Uh-oh. I prefer to take a right-to-left approach. Preferably at the beginning of a project. But even if the project starts left-to-right, I'll do my best to swing it around so that we’re back to a right-to-left approach. (When circumstances are beyond my control, I carry on, but it’s a painful project for everyone – not because of me, but because the approach just doesn’t get to what the business wants in the most effective way.) By using a right to left approach, I try to understand what it is the business is trying to accomplish. I do this by having them explain reports to me, and explaining the decision-making process that relates to these reports. Sometimes I have them explain to me their business processes, or better yet show me their business processes in action because I need pictures, too. I (unofficially) call this part of the project "getting inside the business's head." This is starting at the right side of the diagram above. My next step is to start moving leftward. I do this by preparing some type of prototype. Depending on the nature of the project, this might mean that I simply mock up some data in a relational database and build a prototype report in Reporting Services. If I'm lucky, I might be able to use real data in a relational database. I'll either use a subset of the data in the prototype report by creating a prototype database to hold the sample data, or select data directly from the source. It all depends on how much data there is, how complex the queries are, and how fast I need to get the prototype completed. If the solution will include Analysis Services, then I'll build a prototype cube. Analysis Services makes it incredibly easy to prototype. You can sit down with the business, show them the prototype, and have a meaningful conversation about what the BI solution should look like. I know I've done a good job on the prototype when I get knocked out of my chair so that the business user can explore the solution further independently. (That's really happened to me!) We can talk about dimensions, hierarchies, levels, members, measures, and so on with something tangible to look at and without using those terms. It's not helpful to use sample data like Adventure Works or to use BI terms that they don't really understand. But when I show them their data using the BI technology and talk to them in their language, then they truly have a picture worth a thousand words. From that, we can fine tune the prototype to move it closer to what they want. They have a better idea of what they're getting, and I have a better idea of what to build. So right to left design is not truly moving from the right to the left. But it starts from the right and moves towards the middle, and once I know what the middle needs to look like, I can then build from the left to meet in the middle. And that’s how I get past what the business says to what the business wants.

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  • Why does jQuery do this in its constructor function implementation?

    - by mattcodes
    If we look at the latest jQuery source at http://code.jquery.com/jquery-latest.js we see the following: var jQuery = function( selector, context ) { // The jQuery object is actually just the init constructor 'enhanced' return new jQuery.fn.init( selector, context ); } My understanding of the new keyword in Javascript is essentially JavaScript passes the function an empty object {} and the function sets stuff on it via this.blah. Also from my understanding new differs from .call/.apply etc.. in that the return object also has the prototype set to that of the function. So the return value should have a prototype that the same as jQuery.prototype.init.prototype (or jQuery.fn.init.prototype). However from what I see its prototype is set to jQuery.prototype thus all the commands available to work on the set. Why is this? What am I missing in my understanding?

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  • Design and Implementation with Prototyping Methodology

    - by Shahin
    I'm developing a game for my dissertation, and I'm using the spiral method approach. I'm having a bit of difficulty structuring my dissertation, specifically the design and implementation section. My solution was designed as much as possible initially, and then after each prototype implementation, the design was refined and extended and prototyped again (this was repeated a few times). My problem is how to structure this in my dissertation, my current idea is: Design Chapter Prototype 1 (Initial) Design Prototype 2 Design Prototype 3 Design Implementation Chapter Prototype 1 (Initial) Implementation Prototype 2 Implementation Prototype 3 Implementation Any suggestions?

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  • how is a macro expanded in clojure?

    - by john wang
    In the book Programming Clojure(Stuart), when read how macros are expanded I got confused. user=> (defmacro chain ([x form] (list '. x form)) ([x form & more] (concat (list 'chain (list '. x form)) more))) #'user/chain The above macro can be expanded as: user=> (macroexpand '(chain a b c)) (. (. a b) c) But the following is only expanded to the first level: user=> (macroexpand '(and a b c)) (let* [and__3822__auto__ a] (if and__3822__auto__ (clojure.core/and b c) and__3822__auto__)) The and macro source: user=> (source and) (defmacro and([] true) ([x] x) ([x & next] `(let [and# ~x] (if and# (and ~@next) and#)))) Why is the chain macro expanded all the way but the and not ? Why is it not expanded to something like the following: user=> (macroexpand '(chain a b c d)) (. (chain a b c) d)

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  • On StringComparison Values

    - by Jesse
    When you use the .NET Framework’s String.Equals and String.Compare methods do you use an overloStringComparison enumeration value? If not, you should be because the value provided for that StringComparison argument can have a big impact on the results of your string comparison. The StringComparison enumeration defines values that fall into three different major categories: Culture-sensitive comparison using a specific culture, defaulted to the Thread.CurrentThread.CurrentCulture value (StringComparison.CurrentCulture and StringComparison.CurrentCutlureIgnoreCase) Invariant culture comparison (StringComparison.InvariantCulture and StringComparison.InvariantCultureIgnoreCase) Ordinal (byte-by-byte) comparison of  (StringComparison.Ordinal and StringComparison.OrdinalIgnoreCase) There is a lot of great material available that detail the technical ins and outs of these different string comparison approaches. If you’re at all interested in the topic these two MSDN articles are worth a read: Best Practices For Using Strings in the .NET Framework: http://msdn.microsoft.com/en-us/library/dd465121.aspx How To Compare Strings: http://msdn.microsoft.com/en-us/library/cc165449.aspx Those articles cover the technical details of string comparison well enough that I’m not going to reiterate them here other than to say that the upshot is that you typically want to use the culture-sensitive comparison whenever you’re comparing strings that were entered by or will be displayed to users and the ordinal comparison in nearly all other cases. So where does that leave the invariant culture comparisons? The “Best Practices For Using Strings in the .NET Framework” article has the following to say: “On balance, the invariant culture has very few properties that make it useful for comparison. It does comparison in a linguistically relevant manner, which prevents it from guaranteeing full symbolic equivalence, but it is not the choice for display in any culture. One of the few reasons to use StringComparison.InvariantCulture for comparison is to persist ordered data for a cross-culturally identical display. For example, if a large data file that contains a list of sorted identifiers for display accompanies an application, adding to this list would require an insertion with invariant-style sorting.” I don’t know about you, but I feel like that paragraph is a bit lacking. Are there really any “real world” reasons to use the invariant culture comparison? I think the answer to this question is, “yes”, but in order to understand why we should first think about what the invariant culture comparison really does. The invariant culture comparison is really just a culture-sensitive comparison using a special invariant culture (Michael Kaplan has a great post on the history of the invariant culture on his blog: http://blogs.msdn.com/b/michkap/archive/2004/12/29/344136.aspx). This means that the invariant culture comparison will apply the linguistic customs defined by the invariant culture which are guaranteed not to differ between different machines or execution contexts. This sort of consistently does prove useful if you needed to maintain a list of strings that are sorted in a meaningful and consistent way regardless of the user viewing them or the machine on which they are being viewed. Example: Prototype Names Let’s say that you work for a large multi-national toy company with branch offices in 10 different countries. Each year the company would work on 15-25 new toy prototypes each of which is assigned a “code name” while it is under development. Coming up with fun new code names is a big part of the company culture that everyone really enjoys, so to be fair the CEO of the company spent a lot of time coming up with a prototype naming scheme that would be fun for everyone to participate in, fair to all of the different branch locations, and accessible to all members of the organization regardless of the country they were from and the language that they spoke. Each new prototype will get a code name that begins with a letter following the previously created name using the alphabetical order of the Latin/Roman alphabet. Each new year prototype names would start back at “A”. The country that leads the prototype development effort gets to choose the name in their native language. (An appropriate Romanization system will be used for countries where the primary language is not written in the Latin/Roman alphabet. For example, the Pinyin system could be used for Chinese). To avoid repeating names, a list of all current and past prototype names will be maintained on each branch location’s company intranet site. Assuming that maintaining a single pre-sorted list is not feasible among all of the highly distributed intranet implementations, what string comparison method would you use to sort each year’s list of prototype names so that the list is both meaningful and consistent regardless of the country within which the list is being viewed? Sorting the list with a culture-sensitive comparison using the default configured culture on each country’s intranet server the list would probably work most of the time, but subtle differences between cultures could mean that two different people would see a list that was sorted slightly differently. The CEO wants the prototype names to be a unifying aspect of company culture and is adamant that everyone see the the same list sorted in the same order and there’s no way to guarantee a consistent sort across different cultures using the culture-sensitive string comparison rules. The culture-sensitive sort would produce a meaningful list for the specific user viewing it, but it wouldn’t always be consistent between different users. Sorting with the ordinal comparison would certainly be consistent regardless of the user viewing it, but would it be meaningful? Let’s say that the current year’s prototype name list looks like this: Antílope (Spanish) Babouin (French) Cahoun (Czech) Diamond (English) Flosse (German) If you were to sort this list using ordinal rules you’d end up with: Antílope Babouin Diamond Flosse Cahoun This sort is no good because the entry for “C” appears the bottom of the list after “F”. This is because the Czech entry for the letter “C” makes use of a diacritic (accent mark). The ordinal string comparison does a byte-by-byte comparison of the code points that make up each character in the string and the code point for the “C” with the diacritic mark is higher than any letter without a diacritic mark, which pushes that entry to the bottom of the sorted list. The CEO wants each country to be able to create prototype names in their native language, which means we need to allow for names that might begin with letters that have diacritics, so ordinal sorting kills the meaningfulness of the list. As it turns out, this situation is actually well-suited for the invariant culture comparison. The invariant culture accounts for linguistically relevant factors like the use of diacritics but will provide a consistent sort across all machines that perform the sort. Now that we’ve walked through this example, the following line from the “Best Practices For Using Strings in the .NET Framework” makes a lot more sense: One of the few reasons to use StringComparison.InvariantCulture for comparison is to persist ordered data for a cross-culturally identical display That line describes the prototype name example perfectly: we need a way to persist ordered data for a cross-culturally identical display. While this example is 100% made-up, I think it illustrates that there are indeed real-world situations where the invariant culture comparison is useful.

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