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• A .NET Developers day with the iPad.

  - by mbcrump

  The Apple iPad is currently getting a lot of buzz because of the app store, the book store and of course iTunes. I had the chance to play with one and this is what I have learned about the device. Let’s get this out of the way first, the iPad is awesome. It is the device for media consumption and casual web browsing. But how does it measure up to those of us with .NET on our brains all days. Let’s find out… Main Screen – you can customize everything on this page. I guess I should replace that image with a C# or VS logo. Its pretty standard stuff if you have an iPhone.   Programming Books If you have a subscription to Safari Books Online, then you are in luck, its very easy to read the books on the iPad. Just fire up Safari web browser and goto the Safari Books Online. The biggest benefit that I can see with the iPad is the ability to read books wherever and not have to worry about purchasing books that I already have the .PDF for. Below is a sample from Code Complete 2nd Edition. Below is a PDF of the ECMA-334 C# Language Specification. As you can see its very readable and you should have no problem reading actual code.   Example of Code shown below: It is however easier to read the PDF and store them with a 3rd party PDF reader. I have seen several for .99 cents or less. You can however switch the screen to vertical to get more viewing space as shown below: I was disappointed with the iBooks application. I could not find a single .NET programming book anywhere. I was able to download the excellent sci-fi book “A memory of Wind” for free though. If I just overlooked them, then please email me with the names and titles. I couldn’t even find a technology category in the categories list. Web Surfing – Technical Sites Below is an example of my site in Safari. The code is very readable and the experience was identical to viewing it in Firefox. I tried multiple programming site and the pages looked great except those that used flash and of course it did not display on those pages.   News Apps - Technical Content The standard NY Times and USA Today looked great, but the Technical Content was lacking. It would probably be better to use Google Reader for online technical news.     YouTube Videos – Technical Content  Since its YouTube, we already know that a lot of technical content exist and it plays great on the iPad. I watched several programming videos and could clearly see the code being written. Taking Technical Notes The iPad comes with a great notepad for taking notes. I found that it was easy to take notes regarding projects that I am currently working on.   Calendar The calendar that ships with the iPad is great for organizing. You can setup exchange server or manually enter the information. Pretty standard stuff.    Random Applications that I like: TweetDeck.   and Adobe Ideas. Adobe Ideas is kinda like SketchFlow except you use your finger to mock up the sketches.  Don’t forget that the iPad is great for any type of podcasting. That pretty much sums it up, I would definitely recommend this device as it will only get better. I believe the iOS4 comes out on the 24th and the iPad will only get more and more apps. You could save a few bucks by waiting for the 2nd generation, but that’s a call that only you can make.

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• HLSL 5 interpolation issues

  - by metredigm

  I'm having issues with the depth components of my shadowmapping shaders. The shadow map rendering shader is fine, and works very well. The world rendering shader is more problematic. The only value which seems to definitely be off is the pixel's position from the light's perspective, which I pass in parallel to the position. struct Pixel { float4 position : SV_Position; float4 light_pos : TEXCOORD2; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; The reason that I used the semantic 'TEXCOORD2' on the light's pixel position is because I believe that the problem lies with Direct3D's interpolation of values between shaders, and I started trying random semantics and also forcing linear and noperspective interpolations. In the world rendering shader, I observed in the pixel shader that the Z value of light_pos was always extremely close to, but less than the W value. This resulted in a depth result of 0.999 or similar for every pixel. Here is the vertex shader code : struct Vertex { float3 position : POSITION; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; struct Pixel { float4 position : SV_Position; float4 light_pos : TEXCOORD2; float3 normal : NORMAL; float2 texcoord : TEXCOORD; }; cbuffer Camera : register (b0) { matrix world; matrix view; matrix projection; }; cbuffer Light : register (b1) { matrix light_world; matrix light_view; matrix light_projection; }; Pixel RenderVertexShader(Vertex input) { Pixel output; output.position = mul(float4(input.position, 1.0f), world); output.position = mul(output.position, view); output.position = mul(output.position, projection); output.world_pos = mul(float4(input.position, 1.0f), world); output.world_pos = mul(output.world_pos, light_view); output.world_pos = mul(output.world_pos, light_projection); output.texcoord = input.texcoord; output.normal = input.normal; return output; } I suspect interpolation to be the culprit, as I used the camera matrices in place of the light matrices in the vertex shader, and had the same problem. The problem is evident as both of the same vectors were passed to a pixel from the VS, but only one of them showed a change in the PS. I have already thoroughly debugged the matrices' validity, the cbuffers' validity, and the multiplicative validity. I'm very stumped and have been trying to solve this for quite some time. Misc info : The light projection matrix and the camera projection matrix are the same, generated from D3DXMatrixPerspectiveFovLH(), with an FOV of 60.0f * 3.141f / 180.0f, a near clipping plane of 0.1f, and a far clipping plane of 1000.0f. Any ideas on what is happening? (This is a repost from my question on Stack Overflow)

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• PCI Encryption Key Management

  - by Unicorn Bob

  (Full disclosure: I'm already an active participant here and at StackOverflow, but for reasons that should hopefully be obvious, I'm choosing to ask this particular question anonymously). I currently work for a small software shop that produces software that's sold commercially to manage small- to mid-size business in a couple of fairly specialized industries. Because these industries are customer-facing, a large portion of the software is related to storing and managing customer information. In particular, the storage (and securing) of customer credit card information. With that, of course, comes PCI compliance. To make a long story short, I'm left with a couple of questions about why certain things were done the way they were, and I'm unfortunately without much of a resource at the moment. This is a very small shop (I report directly to the owner, as does the only other full-time employee), and the owner doesn't have an answer to these questions, and the previous developer is...err...unavailable. Issue 1: Periodic Re-encryption As of now, the software prompts the user to do a wholesale re-encryption of all of the sensitive information in the database (basically credit card numbers and user passwords) if either of these conditions is true: There are any NON-encrypted pieces of sensitive information in the database (added through a manual database statement instead of through the business object, for example). This should not happen during the ordinary use of the software. The current key has been in use for more than a particular period of time. I believe it's 12 months, but I'm not certain of that. The point here is that the key "expires". This is my first foray into commercial solution development that deals with PCI, so I am unfortunately uneducated on the practices involved. Is there some aspect of PCI compliance that mandates (or even just strongly recommends) periodic key updating? This isn't a huge issue for me other than I don't currently have a good explanation to give to end users if they ask why they are being prompted to run it. Question 1: Is the concept of key expiration standard, and, if so, is that simply industry-standard or an element of PCI? Issue 2: Key Storage Here's my real issue...the encryption key is stored in the database, just obfuscated. The key is padded on the left and right with a few garbage bytes and some bits are twiddled, but fundamentally there's nothing stopping an enterprising person from examining our (dotfuscated) code, determining the pattern used to turn the stored key into the real key, then using that key to run amok. This seems like a horrible practice to me, but I want to make sure that this isn't just one of those "grin and bear it" practices that people in this industry have taken to. I have developed an alternative approach that would prevent such an attack, but I'm just looking for a sanity check here. Question 2: Is this method of key storage--namely storing the key in the database using an obfuscation method that exists in client code--normal or crazy? Believe me, I know that free advice is worth every penny that I've paid for it, nobody here is an attorney (or at least isn't offering legal advice), caveat emptor, etc. etc., but I'm looking for any input that you all can provide. Thank you in advance!

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• Profiling Startup Of VS2012 &ndash; JustTrace Profiler

  - by Alois Kraus

  JustTrace is made by Telerik which is mainly known for its collection of UI controls. The current version (2012.3.1127.0) does include a performance and memory profiler which does cost 614€ and is currently with a special offer for 306€ on sale. It does include one year of free upgrades. The uneven € numbers are calculated from the 799€ and 50% dicsount price. The UI is already in Metro style and simple to use. Multi process, attach, method recording filter are not supported. It looks like JustTrace is like Ants a Just My Code profiler. For stuff where you do not have the pdbs or you want to dig deeper into the BCL code you will not get far. After getting the profile data you get in the All Methods grid a plain list with hit count and own time. The method list for all methods is also suspiciously short which is a clear sign that you will not get far during the analysis of foreign code. But at least there is also a memory profiler included. For this I have to choose in the first window for Profiling Type “Memory Profiler” to check the memory consumption of VS.  There are some interesting number to see but I do really miss from YourKit the thread stack window. How am I supposed to get a clue when much memory is allocated and the CPU consumption is high in which places I should look? The Snapshot summary gives a rough overview which is ok for a first impression. Next is Assemblies? This gives you a list of all loaded assemblies. Not terribly useful.   The By Type view gives you exactly what it is supposed to do. You have to keep in mind that this list is filtered by the types you did check in the Assemblies list. The By Type instance list does only show types from assemblies which do not originate from Microsoft. By default mscorlib and System are not checked. That is the reason why for the first time my By Type window looked like The idea behind this feature is to show only your instances because you are ultimately responsible for the overall memory consumption. I am not sure if I do like this feature because by default it does hide too much. I do want to see at least how many strings and arrays are allocated. A simple namespace filter would also do it in my opinion. Now you can examine all string instances and look who in the object graph does keep a reference on them. That is nice but YourKit has the big plus that you can also look into the string contents.  I am also not sure how in the graph cycles are visualized and what will happen if you have thousands of objects referencing you. That's pretty much it about JustTrace. It can help the average developer to pinpoint performance and memory issues by just looking at his own code and instances. Showing them more will not help them because the sheer amount of information will overwhelm them. And you need to have a pretty good understanding how the GC and the CLR does work. When you have a performance issue at a customer machine it is sometimes very helpful to be able a bring a profiler onto the machine (no pdbs, …) and to get a full snapshot of all processes which are in the problematic use case involved. For these more advanced use cased JustTrace is certainly the wrong tool. Next: SpeedTrace

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• "The connection has timed out" - Please help!

  - by gon

  I recently installed a fresh Ubuntu 12.04 LTS on a desktop, and the installation itself was successful (other than 'grub rescue' issue that I encountered but fixed) but this connection problem is really giving me a headache. Symptoms: 1. When I open the FireFox browser and try to connect to a website, it just hangs for a while saying "Connecting..." but eventually loads an error page "The connection has timed out". 2. It's not a browser problem (and I tried setting ipv6 thing to "true" at about:config) because running "sudo apt-get install [some-random-package]" at terminal fails ("E: Unable to locate package [package]") too. All other operations that need internet access are not working. 3. I certainly see a wired network (called "eth1") at the Network Manager, and it says "Connection Established" after disconnecting and then connecting again. I have tried almost everything that could be found from google search results still no luck. Their problems slightly differ from mine or the solutions just don't work. By the way it didn't have internet access when installing Ubuntu 12.04. (I ignored the message that I need internet to install Ubuntu) Could this be a problem? I'm sorry I don't remember if internet worked or not on the previous version of Ubuntu. :( I would really appreciate your help... I don't even know what more to do if this fails too.. Thanks!! Thanks for your comment. Here is the result of ifconfig: eth0 Link encap:Ethernet HWaddr 78:ac:c0:3d:b2:b9 inet addr:10.10.65.185 Bcast:10.10.65.255 Mask:255.255.255.0 inet6 addr: fe80::7aac:c0ff:fe3d:b2b9/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:3907 errors:0 dropped:0 overruns:0 frame:0 TX packets:771 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:393118 (393.1 KB) TX bytes:73472 (73.4 KB) Interrupt:16 eth1 Link encap:Ethernet HWaddr 78:ac:c0:3d:b2:b8 UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) Interrupt:17 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:4 errors:0 dropped:0 overruns:0 frame:0 TX packets:4 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:204 (204.0 B) TX bytes:204 (204.0 B) route -n: Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 0.0.0.0 10.10.65.1 0.0.0.0 UG 0 0 0 eth0 10.10.65.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0 169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0 /etc/resolv.conf: # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 8.8.8.8 nameserver 8.8.4.4 nameserver 10.81.1.8 nameserver 10.1.2.10 nameserver 127.0.0.1 search yamatake.local /etc/network/interfaces: auto lo iface lo inet loopback #auto eth0 #iface eth0 inet dhcp #auto eth1 #iface eth1 inet dhcp And I'll also include the result of 'sudo lshw -C network' in case it might help: *-network description: Ethernet interface product: NetXtreme BCM5764M Gigabit Ethernet PCIe vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:02:00.0 logical name: eth0 version: 10 serial: 78:ac:c0:3d:b2:b9 size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm vpd msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.121 duplex=full firmware=5764m-v3.35 ip=10.10.65.185 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s resources: irq:93 memory:fc000000-fc00ffff *-network description: Ethernet interface product: NetXtreme BCM5764M Gigabit Ethernet PCIe vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:01:00.0 logical name: eth1 version: 10 serial: 78:ac:c0:3d:b2:b8 size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm vpd msi pciexpress bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=tg3 driverversion=3.121 duplex=full firmware=5764m-v3.35 latency=0 link=no multicast=yes port=twisted pair speed=100Mbit/s resources: irq:94 memory:fb000000-fb00ffff

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• Come up with a real-world problem in which only the best solution will do (a problem from Introduction to algorithms) [closed]

  - by Mike

  EDITED (I realized that the question certainly needs a context) The problem 1.1-5 in the book of Thomas Cormen et al Introduction to algorithms is: "Come up with a real-world problem in which only the best solution will do. Then come up with one in which a solution that is “approximately” the best is good enough." I'm interested in its first statement. And (from my understanding) it is asked to name a real-world problem where only the exact solution will work as opposed to a real-world problem where good-enough solution will be ok. So what is the difference between the exact and good enough solution. Consider some physics problem for example the simulation of the fulid flow in the permeable medium. To make this simulation happen some simplyfing assumptions have to be made when deriving a mathematical model. Otherwise the model becomes at least complex and unsolvable. Virtually any particle in the universe has its influence on the fluid flow. But not all particles are equal. Those that form the permeable medium are much more influental than the ones located light years away. Then when the mathematical model needs to be solved an exact solution can rarely be found unless the mathematical model is simple enough (wich probably means the model isn't close to reality). We take an approximate numerical method and after hours of coding and days of verification come up with the program or algorithm which is a solution. And if the model and an algorithm give results close to a real problem by some degree that is good enough soultion. Its worth noting the difference between exact solution algorithm and exact computation result. When considering real-world problems and real-world computation machines I believe all physical problems solutions where any calculations are taken can not be exact because universal physical constants are represented approximately in the computer. Any numbers are represented with the limited precision, at least limited by amount of memory available to computing machine. I can imagine plenty of problems where good-enough, good to some degree solution will work, like train scheduling, automated trading, satellite orbit calculation, health care expert systems. In that cases exact solutions can't be derived due to constraints on computation time, limitations in computer memory or due to the nature of problems. I googled this question and like what this guy suggests: there're kinds of mathematical problems that need exact solutions (little note here: because the question is taken from the book "Introduction to algorithms" the term "solution" means an algorithm or a program, which in this case gives exact answer on each input). But that's probably more of theoretical interest. So I would like to narrow down the question to: What are the real-world practical problems where only the best (exact) solution algorithm or program will do (but not the good-enough solution)? There are problems like breaking of cryptographic ciphers where only exact solution matters in practice and again in practice the process of deciphering without knowing a secret should take reasonable amount of time. Returning to the original question this is the problem where good-enough (fast-enough) solution will do there's no practical need in instant crack though it's desired. So the quality of "best" can be understood in any sense: exact, fastest, requiring least memory, having minimal possible network traffic etc. And still I want this question to be theoretical if possible. In a sense that there may be example of computer X that has limited resource R of amount Y where the best solution to problem P is the one that takes not more than available Y for inputs of size N*Y. But that's the problem of finding solution for P on computer X which is... well, good enough. My final thought that we live in a world where it is required from programming solutions to practical purposes to be good enough. In rare cases really very very good but still not the best ones. Isn't it? :) If it's not can you provide an example? Or can you name any such unsolved problem of practical interest?

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• Using WKA in Large Coherence Clusters (Disabling Multicast)

  - by jpurdy

  Disabling hardware multicast (by configuring well-known addresses aka WKA) will place significant stress on the network. For messages that must be sent to multiple servers, rather than having a server send a single packet to the switch and having the switch broadcast that packet to the rest of the cluster, the server must send a packet to each of the other servers. While hardware varies significantly, consider that a server with a single gigabit connection can send at most ~70,000 packets per second. To continue with some concrete numbers, in a cluster with 500 members, that means that each server can send at most 140 cluster-wide messages per second. And if there are 10 cluster members on each physical machine, that number shrinks to 14 cluster-wide messages per second (or with only mild hyperbole, roughly zero). It is also important to keep in mind that network I/O is not only expensive in terms of the network itself, but also the consumption of CPU required to send (or receive) a message (due to things like copying the packet bytes, processing a interrupt, etc). Fortunately, Coherence is designed to rely primarily on point-to-point messages, but there are some features that are inherently one-to-many: Announcing the arrival or departure of a member Updating partition assignment maps across the cluster Creating or destroying a NamedCache Invalidating a cache entry from a large number of client-side near caches Distributing a filter-based request across the full set of cache servers (e.g. queries, aggregators and entry processors) Invoking clear() on a NamedCache The first few of these are operations that are primarily routed through a single senior member, and also occur infrequently, so they usually are not a primary consideration. There are cases, however, where the load from introducing new members can be substantial (to the point of destabilizing the cluster). Consider the case where cluster in the first paragraph grows from 500 members to 1000 members (holding the number of physical machines constant). During this period, there will be 500 new member introductions, each of which may consist of several cluster-wide operations (for the cluster membership itself as well as the partitioned cache services, replicated cache services, invocation services, management services, etc). Note that all of these introductions will route through that one senior member, which is sharing its network bandwidth with several other members (which will be communicating to a lesser degree with other members throughout this process). While each service may have a distinct senior member, there's a good chance during initial startup that a single member will be the senior for all services (if those services start on the senior before the second member joins the cluster). It's obvious that this could cause CPU and/or network starvation. In the current release of Coherence (3.7.1.3 as of this writing), the pure unicast code path also has less sophisticated flow-control for cluster-wide messages (compared to the multicast-enabled code path), which may also result in significant heap consumption on the senior member's JVM (from the message backlog). This is almost never a problem in practice, but with sufficient CPU or network starvation, it could become critical. For the non-operational concerns (near caches, queries, etc), the application itself will determine how much load is placed on the cluster. Applications intended for deployment in a pure unicast environment should be careful to avoid excessive dependence on these features. Even in an environment with multicast support, these operations may scale poorly since even with a constant request rate, the underlying workload will increase at roughly the same rate as the underlying resources are added. Unless there is an infrastructural requirement to the contrary, multicast should be enabled. If it can't be enabled, care should be taken to ensure the added overhead doesn't lead to performance or stability issues. This is particularly crucial in large clusters.

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• Entity System with C++ templates

  - by tommaisey

  I've been getting interested in the Entity/Component style of game programming, and I've come up with a design in C++ which I'd like a critique of. I decided to go with a fairly pure Entity system, where entities are simply an ID number. Components are stored in a series of vectors - one for each Component type. However, I didn't want to have to add boilerplate code for every new Component type I added to the game. Nor did I want to use macros to do this, which frankly scare me. So I've come up with a system based on templates and type hinting. But there are some potential issues I'd like to check before I spend ages writing this (I'm a slow coder!) All Components derive from a Component base class. This base class has a protected constructor, that takes a string parameter. When you write a new derived Component class, you must initialise the base with the name of your new class in a string. When you first instantiate a new DerivedComponent, it adds the string to a static hashmap inside Component mapped to a unique integer id. When you subsequently instantiate more Components of the same type, no action is taken. The result (I think) should be a static hashmap with the name of each class derived from Component that you instantiate at least once, mapped to a unique id, which can by obtained with the static method Component::getTypeId ("DerivedComponent"). Phew. The next important part is TypedComponentList<typename PropertyType>. This is basically just a wrapper to an std::vector<typename PropertyType> with some useful methods. It also contains a hashmap of entity ID numbers to slots in the array so we can find Components by their entity owner. Crucially TypedComponentList<> is derived from the non-template class ComponentList. This allows me to maintain a list of pointers to ComponentList in my main ComponentManager, which actually point to TypedComponentLists with different template parameters (sneaky). The Component manager has template functions such as: template <typename ComponentType> void addProperty (ComponentType& component, int componentTypeId, int entityId) and: template <typename ComponentType> TypedComponentList<ComponentType>* getComponentList (int componentTypeId) which deal with casting from ComponentList to the correct TypedComponentList for you. So to get a list of a particular type of Component you call: TypedComponentList<MyComponent>* list = componentManager.getComponentList<MyComponent> (Component::getTypeId("MyComponent")); Which I'll admit looks pretty ugly. Bad points of the design: If a user of the code writes a new Component class but supplies the wrong string to the base constructor, the whole system will fail. Each time a new Component is instantiated, we must check a hashed string to see if that component type has bee instantiated before. Will probably generate a lot of assembly because of the extensive use of templates. I don't know how well the compiler will be able to minimise this. You could consider the whole system a bit complex - perhaps premature optimisation? But I want to use this code again and again, so I want it to be performant. Good points of the design: Components are stored in typed vectors but they can also be found by using their entity owner id as a hash. This means we can iterate them fast, and minimise cache misses, but also skip straight to the component we need if necessary. We can freely add Components of different types to the system without having to add and manage new Component vectors by hand. What do you think? Do the good points outweigh the bad?

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• How to introduce a computer illiterate 50-year old to programming [closed]

  - by sunday

  The other day my dad asked me a question that I would have never expected from him. "How can I learn C++?" My dad is turning 56 this year and computers are a distant concept for him. He doesn't know how to use a phone very well besides calling numbers (no speed dial or contacts); though he has started to learn computers a little better - to the point that he knows how to open the internet (in Windows) and browse around (and has successfully completed several job applications entirely on his own online, of which he was offered positions too). But still, these are too narrow-windowed experiences to mean much, really. While he may not have the background, my dad knows how to read. And I mean reading as a skill, not just an ability. He has little to no college education (financial problems, family, etc.) and was fortunate enough to finish high school, but still taught himself to become a master electrician and has been one for almost 30 years now. He did the same with guitar, learning to play at a very professional level and has been praised for his skill. In high school, he picked up a weight lifting book - and was the only person in his high school at the time to qualify officially as an "athlete" by national standards. In all cases, he just needed something to read. Something to teach him. He absorbs information like a sponge. I have no doubt in my dad's motivation or capability of doing this, so my general goal is simply: Get my dad into the world of computers, and get him on the road to programming. I strongly believe that once I get him through the fundamentals, his drive and reading skill will keep him going on this own. So I'm asking you all: where should I start with all this? And what are the best resources out there? Should I get him to start Linux instead of Windows? Is C++ a bad idea? Remember, he needs to (IMO) learn computers first, and then get that first grasp (the "Hello world" experience) of programming. For money's sake and at top preference, I'd like free online resources that he can read, but by all means any good suggestions in print or paid-for-online are welcome (that I could possibly look into later to purchase). And also, I intend to start him off with C++ (no Python, Java, etc.), because I know it the best and will be able to help him along the way with code. (I have minimal knowledge right now in other languages). Edit: I'm getting a lot of persistent suggestions to use Python. The only reason I wanted to do C++ is that I KNOW it and can be THERE when my dad needs help. My VERY FIRST exposure to programming ever was Java. I learned Java, and I got good at it. I open to other suggestions, but please provide an effective application of your suggestions. EDIT #2: I understand my approach/thinking/knowledge could be lacking here. I'm a sophomore level undergraduate CS major. If you don't agree with anything in my post, tell me why - give me ideas, information - that's why I'm asking in the first place. To narrow down my general goal to specific reachable goals.

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• Concurrent Affairs

  - by Tony Davis

  I once wrote an editorial, multi-core mania, on the conundrum of ever-increasing numbers of processor cores, but without the concurrent programming techniques to get anywhere near exploiting their performance potential. I came to the.controversial.conclusion that, while the problem loomed for all procedural languages, it was not a big issue for the vast majority of programmers. Two years later, I still think most programmers don't concern themselves overly with this issue, but I do think that's a bigger problem than I originally implied. Firstly, is the performance boost from writing code that can fully exploit all available cores worth the cost of the additional programming complexity? Right now, with quad-core processors that, at best, can make our programs four times faster, the answer is still no for many applications. But what happens in a few years, as the number of cores grows to 100 or even 1000? At this point, it becomes very hard to ignore the potential gains from exploiting concurrency. Possibly, I was optimistic to assume that, by the time we have 100-core processors, and most applications really needed to exploit them, some technology would be around to allow us to do so with relative ease. The ideal solution would be one that allows programmers to forget about the problem, in much the same way that garbage collection removed the need to worry too much about memory allocation. From all I can find on the topic, though, there is only a remote likelihood that we'll ever have a compiler that takes a program written in a single-threaded style and "auto-magically" converts it into an efficient, correct, multi-threaded program. At the same time, it seems clear that what is currently the most common solution, multi-threaded programming with shared memory, is unsustainable. As soon as a piece of state can be changed by a different thread of execution, the potential number of execution paths through your program grows exponentially with the number of threads. If you have two threads, each executing n instructions, then there are 2^n possible "interleavings" of those instructions. Of course, many of those interleavings will have identical behavior, but several won't. Not only does this make understanding how a program works an order of magnitude harder, but it will also result in irreproducible, non-deterministic, bugs. And of course, the problem will be many times worse when you have a hundred or a thousand threads. So what is the answer? All of the possible alternatives require a change in the way we write programs and, currently, seem to be plagued by performance issues. Software transactional memory (STM) applies the ideas of database transactions, and optimistic concurrency control, to memory. However, working out how to break down your program into sufficiently small transactions, so as to avoid contention issues, isn't easy. Another approach is concurrency with actors, where instead of having threads share memory, each thread runs in complete isolation, and communicates with others by passing messages. It simplifies concurrent programs but still has performance issues, if the threads need to operate on the same large piece of data. There are doubtless other possible solutions that I haven't mentioned, and I would love to know to what extent you, as a developer, are considering the problem of multi-core concurrency, what solution you currently favor, and why. Cheers, Tony.

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• Appropriate design / technologies to handle dynamic string formatting?

  - by Mark W

  recently I was tasked with implementing a way of adding support for versioning of hardware packet specifications to one of our libraries. First a bit of information about the project. We have a hardware library which has classes for each of the various commands we support sending to our hardware. These hardware modules are essentially just lights with a few buttons, and a 2 or 4 digit display. The packets typically follow the format {SOH}AADD{ETX}, where AA is our sentinel action code, and DD is the device ID. These packet specs are different from one command to the next obviously, and the different firmware versions we have support different specifications. For example, on version 1 an action code of 14 may have a spec of {SOH}AADDTEXT{ETX} which would be AA = 14 literal, DD = device ID, TEXT = literal text to display on the device. Then we come out with a revision with adds an extended byte(s) onto the end of the packet like this {SOH}AADDTEXTE{ETX}. Assume the TEXT field is fixed width for this example. We have now added a new field onto the end which could be used to say specify the color or flash rate of the text/buttons. Currently this java library only supports one version of the commands, the latest. In our hardware library we would have a class for this command, say a DisplayTextArgs.java. That class would have fields for the device ID, the text, and the extended byte. The command class would expose a method which generates the string ("{SOH}AADDTEXTE{ETX}") using the value from the class. In practice we would create the Args class as needed, populate the fields, call the method to get our packet string, then ship that down across the CAN. Some of our other commands specification can vary for the same command, on the same version, depending on some runtime state. For example, another command for version 1 may be {SOH}AA{ETX}, where this action code clears all of the modules behind a specific controller device of their text. We may overload this packet to have option fields with multiple meanings like {SOH}AAOC{ETX} where OC is literal text, which tells the controller to only clear text on a specific module type, and to leave the others alone, or the spec could also have an option format of {SOH}AADD{ETX} to clear the text off a a specific device. Currently, in the method which generates the packet string, we would evaluate fields on the args class to determine which spec we will be using when formatting the packet. For this example, it would be along the lines of: if m_DeviceID != null then use {SOH}AADD{ETX} else if m_ClearOCs == true then use {SOH}AAOC{EXT} else use {SOH}AA{ETX} I had considered using XML, or a database to store String.format format strings, which were linked to firmware version numbers in some table. We would load them up at startup, and pass in the version number of the hardwares firmware we are currently using (I can query the devices for their firmware version, but the version is not included in all packets as part of the spec). This breaks down pretty quickly because of the dynamic nature of how we select which version of the command to use. I then considered using a rule engine to possibly build out expressions which could be interpreted at runtume, to evaluate the args class's state, and from that select the appropriate format string to use, but my brief look at rule engines for java scared me away with its complexity. While it seems like it might be a viable solution, it seems overly complex. So this is why I am here. I wouldn't say design is my strongest skill, and im having trouble figuring out the best way to approach this problem. I probably wont be able to radically change the args classes, but if the trade off was good enough, I may be able to convince my boss that the change is appropriate. What I would like from the community is some feedback on some best practices / design methodologies / API or other resources which I could use to accomplish: Logic to determine which set of commands to use for a given firmware version Of those command, which version of each command to use (based on the args classes state) Keep the rules logic decoupled from the application so as to avoid needing releases for every firmware version Be simple enough so I don't need weeks of study and trial and error to implement effectively.

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• Taking a look at the Mindscape Phone Elements for WP7.

  - by mbcrump

  I recently heard that Mindscape HQ had released the Windows Phone 7 Controls and had to take a look at them. 100 FREE LICENSE GIVEAWAY! Before we get to the screenshots, you will be pleased to learn that my usergroup called “Allaboutxaml” has partnered with Mindscape HQ and are giving away 100 license. You can check out the site here to get your free controls. But please hurry as after the 100 are gone then I will not have any more to give away! A few links to read first: The official blog post from Mindscape HQ detailing the release. They also have the links to download the trial and get started. The phone elements official forum! So, let’s get started. After you download the controls go ahead and double click the .exe to get started installing them. After everything is installed then you will have the following program group. I’d recommend clicking on the Phone Elements Directory to get started: Let’s go over each element: Bin – Just the .DLL that’s required to use Mindscape HQ WP7 Controls in your project. Documentation – a .CHM File that will show you how to get your project up and running quickly. Resources – Just a few image files Samples – This is a full WP7 project that details every controls. The thing that I was most interested in was how the controls look and is it easy to use. I always believed if your paying for controls then you should hold my hand through using them. You will be pleased to know that Mindscape made it very easy to use. First, the WP7 project in the “Samples” folder just works. Double click on the solution file and you are in an emulator looking at the controls. Since you have the source code for every control, it’s a matter of copying/pasting the code in your project to get it to work. What I did, was play with the controls in the emulator until I found one I could use. Then I looked at the Visual Studio solution and found the Page that contained the control. Mindscape makes this very easy to do with their layout: So, the one that I was interested in was the Looping List Box.  Here is a demo of it: I wanted to see how they were populating the numbers 1-100 so I found the code behind and noticed it was just this one line. LoopingListBox1.DataSource = new NumericDataSource() { MinValue = 1, MaxValue = 100 }; In case you are wondering, the NumericDataSource was created by MindScape and you can view the Declaration to find out more about it:   So, the controls are pretty much that easy to use. Play with the emulator and find the control you want to use. Find the XAML file in the Sample Solution and copy/paste the code. Let’s go ahead and take a look at the controls available: They also have a great variety of Charting controls: Overall it’s a nice set of WP7 controls. Feel free to leave a comment below on anything you would like to see and I will make sure that Mindscape HQ get the message. Don’t forget if you are the first 100 people reading this article then you will get a free license.  Subscribe to my feed CodeProject

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• I need help with 2D collision response (of stacking rotating polygons, with friction and gravity, for a game)

  - by Register Sole

  Hi I am looking for suggestions on how to write a collision response for game programming purpose (so not a scientific simulation). I am dealing with 2D polygons that are rotating, and I want them to be able to stack. I also want friction and gravity. I have a detection mechanism that returns the separating axis, how long the polygons are overlapping, and up to 2 points of contact. For the response, I am currently using an impulse-based response, which main idea is: find the separating axis, length of overlap, and the point of contact (if there are two, pick a random point between to simulate averaged force. i believe there are better ways than this) separate the object (modifying their positions, taking into account of their masses. i do not separate them completely though, to keep track that they are colliding to reduce jitter) calculate normal force based on the coefficient of restitution as if there is no friction. calculate friction, as if there is no normal force. I also assume that the direction of the friction is the same throughout the collision. apply the two forces (which result in a rather inaccurate result, since each force is calculated as if the other is not present. for non-rotating bodies though, this method is exact) I am aware that this method requires the coefficient of friction to be sufficiently small due to the assumption that the direction of friction stays the same in a collision. Also, the result is visually satisfying if gravity is not present. However, when there is gravity, objects on ground jitter and drift (even with zero coefficient of restitution)! It also happens for stacking objects. Larger coefficient of restitution and gravity increase the jittering. I hope you can help me with this. Some things i would like to know more about is how to handle collision with two point of contacts (how to end up having an object sitting still on the ground?), how to reduce, and prevent if possible, jitter and drift (do people use the most accurate method possible, or is there a trick to overcome this?), and how to handle multiple objects collision (for example, in the case of stacking objects, how do I check collisions between all of them and keep them all stable at every frame so they don't jitter?). A total reformulation of my algorithm is also welcomed, as long as it works. Another thing to note is that I am not making a Physics game, so I only need a visually satisfying response (though a realistic response is preferable, if it is not performance-heavy). But surely jittering and drifting objects on flat ground are not at all acceptable. In addition, I am a Physics student, so feel free to talk about impulse and whatever needed. Finally, I'm sorry for the long post. I tried to be as concise as I can. Thank you for reading it! EDIT It seems what I didn't manage to come up all this time is to separate resting contact as a class of its own and how to solve them. Currently reading the paper suggested by Jedediah. More suggestions on the topic are welcome :) CASE CLOSED After reading various papers referenced in the paper, successfully implemented simultaneous impulse method (referring to the original paper by Erin Catto, [Catt05]). Thanks maaaan!! The paper is wonderful. The current system is visibly much better than the previous. Still haven't separated resting contact as a class of its own though, which brings me to my next question. Love you all! Haha (sorry, I'm just so happy thanks to you).

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• Why is 0 false?

  - by Morwenn

  This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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• GMLib Could not complete the operation due to error 80020101

  - by Pierrie

  I get this error "Could not complete the operation due to error 80020101." at random times when displaying a map with a marker on it. I use Delphi 2007 and GMLib [1.2.0 Final]. I have read up on the issue and some suggestions was that the problem is due to commenting or bad syntax in java code, and it was suggested that i take out all the commenting and check for errors in the java code. This i did, i recompiled and reinstalled GMLib after modifying the map.html file. I stripped it of all commenting and parsed it through ie for faults but found none, as expected. But the problem still occurs. Here is a sample of my code to show the map and add the marker : Var newmarker : TMarker; begin newmarker := GMMarker1.Add(); newmarker.Position.Lat := MarkersToPaint[i].Latitude; newmarker.Position.Lng := MarkersToPaint[i].Longitude; newmarker.Visible := True; newmarker.Title := MarkersToPaint[i].Title; GMMap1.RequiredProp.Center.Lat := midlat; GMMap1.RequiredProp.Center.Lng := midlong; GMMap1.RequiredProp.Zoom := 18; GMMarker1.ShowElements; GMMap1.Active := True; Any help in this matter will be greatly appreciated.

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• Detect user logout / shutdown in Python / GTK under Linux

  - by Ivo Wetzel

  OK this is presumably a hard one, I've got an pyGTK application that has random crashes due to X Window errors that I can't catch/control. So I created a wrapper that restarts the app as soon as it detects a crash, now comes the problem, when the user logs out or shuts down the system, the app exits with status 1. But on some X errors it does so too. So I tried literally anything to catch the shutdown/logout, with no success, here's what I've tried: import pygtk import gtk import sys class Test(gtk.Window): def delete_event(self, widget, event, data=None): open("delete_event", "wb") def destroy_event(self, widget, data=None): open("destroy_event", "wb") def destroy_event2(self, widget, event, data=None): open("destroy_event2", "wb") def __init__(self): gtk.Window.__init__(self, gtk.WINDOW_TOPLEVEL) self.show() self.connect("delete_event", self.delete_event) self.connect("destroy", self.destroy_event) self.connect("destroy-event", self.destroy_event2) def foo(): open("add_event", "wb") def ex(): open("sys_event", "wb") from signal import * def clean(sig): f = open("sig_event", "wb") f.write(str(sig)) f.close() exit(0) for sig in (SIGABRT, SIGILL, SIGINT, SIGSEGV, SIGTERM): signal(sig, lambda *args: clean(sig)) def at(): open("at_event", "wb") import atexit atexit.register(at) f = Test() sys.exitfunc = ex gtk.quit_add(gtk.main_level(), foo) gtk.main() open("exit_event", "wb") Not one of these succeeds, is there any low level way to detect the system shutdown? Google didn't find anything related to that. I guess there must be a way, am I right? :/

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• Raphael js text positioning: centering text in a circle

  - by j-man86

  Hey everyone, I am using Raphael js to draw circled numbers. The problem is that each number has a different width/height so using one set of coordinates to center the text isn't working. The text displays differently between IE, FF, and safari. Is there a dynamic way to find the height/width of the number and center it accordingly? Here is my test page: http://jesserosenfield.com/fluid/test.html and my code: function drawcircle(div, text) { var paper = Raphael(div, 26, 26); //<< var circle = paper.circle(13, 13, 10.5); circle.attr("stroke", "#f1f1f1"); circle.attr("stroke-width", 2); var text = paper.text(12, 13, text); //<< text.attr({'font-size': 15, 'font-family': 'FranklinGothicFSCondensed-1, FranklinGothicFSCondensed-2'}); text.attr("fill", "#f1f1f1"); } window.onload = function () { drawcircle("c1", "1"); drawcircle("c2", "2"); drawcircle("c3", "3"); }; Thanks very much!

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• HttpWebRequest sessionID c# login

  - by warne

  Im trying to login to a website (www.vodafone.ie) with a console app and c# httpWebRequest. Problem is it works ok about 50% of the time. Im using fiddler to find out the GET and POST requests I need to make. Done that and my app is successfully recreating these as best as I can see. The steps are; 1) GET request with cookie container to login uri. server response sets new cookie called jsessionID 2) do POST request with login credentials and same cookie container containing previous jsessionID. Looking at the fiddler logs for successful POST request login (browser or my app) I see it sets a thing in the response header : "Set-cookie: supercookie=-; Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=". What is this supercookie thing? Its not returned to me in the response cookie collection like the jsessionID. On rare occasions, there is along string of numbers with the supercookie instead of just "-". I made sure to clear all cookies before analyzing the request/response headers. If the super cookie thing is not being set in the reponse my login fails. So just wondering what's going on here? cheers!

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• Abcpdf throwing System.ExecutionEngineException

  - by Tom Tresansky

  I have the binary for several pdf files stored in a collection of Byte arrays. My goal is to concatenate them into a single .pdf file using abcpdf, then stream that newly created file to the Response object on a page of an ASP.Net website. Had been doing it like this: BEGIN LOOP ... 'Create a new Doc Dim doc As Doc = New Doc 'Read the binary of the current PDF doc.Read(bytes) 'Append to the master merged PDF doc _mergedPDFDoc.Append(Doc) END LOOP Which was working fine 95% of the time. Every now and then however, creating a new Doc object would throw a System.ExecutionEngineException and crash the CLR. It didn't seem to be related to a large number of pdfs (sometimes would happen w/ only 2), or with large sized pdfs. It seemed almost completely random. This is a known bug in abcpdf described (not very well) here Item 6.24. I came across a helpful SO post which suggested using a Using block for the abcpdf Doc object. So now I'm doing this: Using doc As New Doc 'Read the binary of the current PDF doc.Read(bytes) 'Append to the master merged PDF doc _mergedPDFDoc.Append(doc) End Using And I haven't seen the problem occur again yet, and have been pounding on a test version as best as I can to get it to. Has anyone had any similar experience with this error? Did this fix it?

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• SPFileVersionCollection - why versions are sorted in mixed order?

  - by Janis Veinbergs

  SPFileVersionCollection and SPListItemVersionCollection versioning seems inconsistent to me. Inconsistency wouldn't be a problem to me, but sort order is. SPListItemVersionCollection I can understand versioning of ListItems as they are stored in descending order: SPContext.Current.ListItem.Versions.Count -> 5 SPContext.Current.ListItem.Versions[0].VersionId -> 1026 (2.2 latest version) SPContext.Current.ListItem.Versions[1].VersionId -> 1025 (2.1) SPContext.Current.ListItem.Versions[2].VersionId -> 1024 (2.0) ... [4].VersionId -> (oldest version) SPFileVersionCollection However I can't understand how version numbers are saved for a document library item: SPContext.Current.ListItem.File.Versions.Count -> 4 SPContext.Current.ListItem.File.Versions[0].ID -> 512 (1.0 oldest one) SPContext.Current.ListItem.File.Versions[1].ID -> 513 (1.1) SPContext.Current.ListItem.File.Versions[2].ID -> 1025 (2.1 latest version) SPContext.Current.ListItem.File.Versions[3].ID -> 1024 (2.0 (EDIT: IsCurrentVersion = True)) They are nor in ascending order, nor descending, but something mixed. Is there any reason for SharePoint team to decide to store SPFile versions like that? And do they expect that I write my own method to get latest version or is there a builtin one for that? A note: Let me point out that SPListItem.File is not null for document library items.

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• Add a row to UITableView for adding new item?

  - by David.Chu.ca

  In order to provide UI for user to add new items to my table view, I would like to add a new row in my table at a specified location (last row for example) when the view is in edit mode (I have a edit button on the view's navigation bar right side). This new row will have a add button indicator on the left side and disclosure accessory arrow on the right. When the view is not in edit mode, this add row should not be displayed. I am not sure if I should overwrite: - (void)setEditing:(BOOL)editing animated:(BOOL)animated{...} where I call the UITableView's method: insertRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation: (UITableViewRowAnimation)animation to insert a new row? My understanding is that this call may add a new row into the table view. The table view's data source is from CoreData storage. Not sure this may cause inconsistent numbers of data in the data store and table view? If it is OK and I have to manage rows in the table view, how can I add left add indicator and left disclosure arrow to the new row? Another question is that if I can do it to insert a new row as Add row, should I remove it when the table view not in edit mode? Just want to know if I am on the right track.

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• WinForms ComboBox DropDown and Autocomplete window both appear

  - by Clyde

  I've got a combobox on a winforms app with this code: comboBox1.AutoCompleteMode = AutoCompleteMode.SuggestAppend; comboBox1.AutoCompleteSource = AutoCompleteSource.ListItems; DataTable t = new DataTable(); t.Columns.Add("ID", typeof(int)); t.Columns.Add("Display", typeof(string)); for (int i = 1; i < 2000; i++) { t.Rows.Add(i, i.ToString("N0")); } comboBox1.DataSource = t; comboBox1.ValueMember = "ID"; comboBox1.DisplayMember = "Display"; I then follow these steps when the window opens: Click the combobox drop down button -- this displays the list of items and selects the text in the combobox Type '5', '1' ... i.e. I'm looking to use autocomplete to search for 515, 516, etc. You'll see that the autocomplete window now appears ON TOP of the drop down list. However if I mouse over, it's the obscured drop down window behind the autocomplete window that's receiving the mouse events, including the click. So I think I'm clicking on an autocomplete item but actually clicking on something totally random that I can't see. Is this a bug in the ComboBox? I'm using Windows 7 if that matters. Am I configuring the ComboBox wrong somehow? Note also that using the KEYBOARD uses the autocomplete drop down. So up/down arrow keys are using the front window, but the mouse is using the back window.

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• cPickle ImportError: No module named multiarray

  - by Rafal

  Hello, I'm using cPickle to save my Database into file. The code looks like that: def Save_DataBase(): import cPickle from scipy import * from numpy import * a=Results.VersionName #filename='D:/results/'+a[a.find('/')+1:-a.find('/')-2]+Results.AssType[:3]+str(random.randint(0,100))+Results.Distribution+".lft" filename='D:/results/pppp.lft' plik=open(filename,'w') DataOutput=[[[DataBase.Arrays.Nodes,DataBase.Arrays.Links,DataBase.Arrays.Turns,DataBase.Arrays.Connectors,DataBase.Arrays.Zones], [DataBase.Nodes.Data,DataBase.Links.Data,DataBase.Turns.Data,DataBase.OrigConnectors.Data,DataBase.DestConnectors.Data,DataBase.Zones.Data], [DataBase.Nodes.DictionaryPy2Vis,DataBase.Links.DictionaryPy2Vis,DataBase.Turns.DictionaryPy2Vis,DataBase.OrigConnectors.DictionaryPy2Vis,DataBase.DestConnectors.DictionaryPy2Vis,DataBase.Zones.DictionaryPy2Vis], [DataBase.Nodes.DictionaryVis2Py,DataBase.Links.DictionaryVis2Py,DataBase.Turns.DictionaryVis2Py,DataBase.OrigConnectors.DictionaryVis2Py,DataBase.DestConnectors.DictionaryVis2Py,DataBase.Zones.DictionaryVis2Py], [DataBase.Paths.List]],[Results.VersionName,Results.noZones,Results.noNodes,Results.noLinks,Results.noTurns,Results.noTrips, Results.Times.VersionLoad,Results.Times.GetData,Results.Times.GetCoords,Results.Times.CrossTheTime,Results.Times.Plot_Cylinder, Results.AssType,Results.AssParam,Results.tStart,Results.tEnd,Results.Distribution,Results.tVector]] cPickle.dump(DataOutput, plik, protocol=0) plik.close()` And it works fine. Most of my Database rows are lists of a lists, vecor-like, or array-like data sets. But now when I input data, an error occurs: def Load_DataBase(): import cPickle from scipy import * from numpy import * filename='D:/results/pppp.lft' plik= open(filename, 'rb') """ first cPickle load approach """ A= cPickle.load(plik) """ fail """ """ Another approach - data format exact as in Output step above , also fails""" [[[DataBase.Arrays.Nodes,DataBase.Arrays.Links,DataBase.Arrays.Turns,DataBase.Arrays.Connectors,DataBase.Arrays.Zones], [DataBase.Nodes.Data,DataBase.Links.Data,DataBase.Turns.Data,DataBase.OrigConnectors.Data,DataBase.DestConnectors.Data,DataBase.Zones.Data], [DataBase.Nodes.DictionaryPy2Vis,DataBase.Links.DictionaryPy2Vis,DataBase.Turns.DictionaryPy2Vis,DataBase.OrigConnectors.DictionaryPy2Vis,DataBase.DestConnectors.DictionaryPy2Vis,DataBase.Zones.DictionaryPy2Vis], [DataBase.Nodes.DictionaryVis2Py,DataBase.Links.DictionaryVis2Py,DataBase.Turns.DictionaryVis2Py,DataBase.OrigConnectors.DictionaryVis2Py,DataBase.DestConnectors.DictionaryVis2Py,DataBase.Zones.DictionaryVis2Py], [DataBase.Paths.List]],[Results.VersionName,Results.noZones,Results.noNodes,Results.noLinks,Results.noTurns,Results.noTrips, Results.Times.VersionLoad,Results.Times.GetData,Results.Times.GetCoords,Results.Times.CrossTheTime,Results.Times.Plot_Cylinder, Results.AssType,Results.AssParam,Results.tStart,Results.tEnd,Results.Distribution,Results.tVector]]= cPickle.load(plik)` Error is (in both cases): A= cPickle.load(plik) ImportError: No module named multiarray Any Ideas? PS.

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• Negative ItemCount in SharePoint Document Library

  - by ccomet

  What can be done about negative numbers in library item counts? ItemCount is a read-only property, what are you supposed to do when it is drastically incorrect? Earlier last week, I was doing some testing involving the copying and moving of files and folders from one document library to another. I was transfering the items from our actual document library to a sandbox "Test" library that I used to run all sorts of object model and workflow testing in before migrating to the public lists and libraries. I noticed that with files, things worked correctly, but when I copied a folder that had a file inside it (using SPFolder.CopyTo()), the item count for the test library did not actually update. Since this testing was mostly playing around, I paid it little heed. Today I was back in the test library to test a different workflow (regarding PDF conversion). While I was there, I decided to delete the folder I left last week since I didn't need it anymore. And that's when I saw the item count for the list drop to -1 in the All Site Content View. When I deleted the new PDF I had just uploaded, it then dropped to -2! I even checked with the object model... getting an instance of the library I checked the ItemCount property... lo and behold it was also -2. Is there any process which runs in the background, kinda like the one that cleans up workflow history, which will correct this kind of issue? Or is a programmer expected to keep watch for this kind of situation and come up with calculations to compensate the "count penalty", as it were?

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• Gomoku array-based AI-algorithm?

  - by Lasse V. Karlsen

  Way way back (think 20+ years) I encountered a Gomoku game source code in a magazine that I typed in for my computer and had a lot of fun with. The game was difficult to win against, but the core algorithm for the computer AI was really simply and didn't account for a lot of code. I wonder if anyone knows this algorithm and has some links to some source or theory about it. The things I remember was that it basically allocated an array that covered the entire board. Then, whenever I, or it, placed a piece, it would add a number of weights to all locations on the board that the piece would possibly impact. For instance (note that the weights are definitely wrong as I don't remember those): 1 1 1 2 2 2 3 3 3 444 1234X4321 3 3 3 2 2 2 1 1 1 Then it simply scanned the array for an open location with the lowest or highest value. Things I'm fuzzy on: Perhaps it had two arrays, one for me and one for itself and there was a min/max weighting? There might've been more to the algorithm, but at its core it was basically an array and weighted numbers Does this ring a bell with anyone at all? Anyone got anything that would help?

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