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  • Boiler plate code replacement - is there anything bad about this code?

    - by Benjol
    I've recently created these two (unrelated) methods to replace lots of boiler-plate code in my winforms application. As far as I can tell, they work ok, but I need some reassurance/advice on whether there are some problems I might be missing. (from memory) static class SafeInvoker { //Utility to avoid boiler-plate InvokeRequired code //Usage: SafeInvoker.Invoke(myCtrl, () => myCtrl.Enabled = false); public static void Invoke(Control ctrl, Action cmd) { if (ctrl.InvokeRequired) ctrl.BeginInvoke(new MethodInvoker(cmd)); else cmd(); } //Replaces OnMyEventRaised boiler-plate code //Usage: SafeInvoker.RaiseEvent(this, MyEventRaised) public static void RaiseEvent(object sender, EventHandler evnt) { var handler = evnt; if (handler != null) handler(sender, EventArgs.Empty); } } EDIT: See related question here UPDATE Following on from deadlock problems (related in this question), I have switched from Invoke to BeginInvoke (see an explanation here). Another Update Regarding the second snippet, I am increasingly inclined to use the 'empty delegate' pattern, which fixes this problem 'at source' by declaring the event directly with an empty handler, like so: event EventHandler MyEventRaised = delegate {};

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  • tips for learning from opensource

    - by dole doug
    Hi there, Besides practice(practice and more practice) reading books and forums, analyzing others people code is a must in order to have a career in this field. The problem is that I'm a student(feels like always on learning stage) but sometimes i can't solve the problems by my own. I was thinking that on public open source repositories might be the answer I'm looking for. My question is how can i find the answer to some of my problems in open source projects/community? Do you have any tips to share for me? ty

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  • Convet long/lat to pixel x/y on a given picure.

    - by kalininew
    I have a city "map" (for example - Moscow). She in accuracy repeats the contours the given city in google maps (that is it is copied from google maps and it is a little processed, but the sense remained the same). Also I have object co-ordinates in a city (in co-ordinates of google). Problem: how to translate google co-ordinates to the co-ordinates of my picture (that is in pixels on OX and OY on a picture). That is I receive google-co-ordinates and it is necessary for me to draw this point on my picture. I know that on small scales (for example on city scales) it to make simply enough (it is necessary to learn what google-co-ordinates has one of picture corners, then to learn "price" of one pixel in google-co-ordinates on a picture on axes OX and OY separately). But on the big scales (country scale) "price" of one pixel will be not a constant, and will vary strongly enough and the method described above cannot be applied. How to solve a problem on country scales?

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  • Things you should implement in your own programming language

    - by I can't tell you my name.
    I've created an experimental toy programming language with a (now) working interpreter. It is turing-complete and has a pretty low-level instruction set. Even if everything takes four to six times more code and time than in PHP, Python or Ruby I still love programming all kinds of things in it. So I got the "basic" things that are written in many languages working: Hello World Input - Output Countdowns (not as easy as you think as there are no loops) Factorials Array emulation 99 Bottles of Beer (simple, wrong inflection) 99 Bottles of Beer (canonical) Conjatz conjecture Quine (that was a fun one!) Brainf*ck interpreter (To proof turing-completeness, made me happy) So I implemented all of the above examples because: They all used many different aspects of the language They are pretty interesting They don't take hours to write Now my problem is: I've run out of ideas! I don't find any more examples of what problems I could solve using my language. Do you have any programming problems which fit into some of the criteria above for me to work out?

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  • changing Python code in the debugger

    - by max
    Is there any debugger that allows Python code to be changed while debugging? In other words: run-time exception occurs, debugger stops, I change the code any way I like, and tell the program to continue. I am aware of the problems with this approach, such that references to functions would still point to the old definitions if I redefine the function on the fly, and so on. I am ok with that, since I just want to be able to make small fixes in very simple circumstances. On the other hand, I'm also interested in whether it's theoretically possible to allow changes to Python code without running into these problems: i.e., somehow update all the references to the objects that changed, etc. I'm nearly sure the answer to the second question is no, but if I'm wrong, I'd like to know. EDIT: If my goal (changing the code interactively when an exception occurred, and then continuing execution), is achievable without a debugger - that would be good as well. I don't need to use the debugger.

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  • Richfaces modal panel and a4j:keepAlive

    - by mykola
    Hello! I've got unexpected problems with richfaces (3.3.2) modal panel. When i try to open it, browser opens two panels instead of one: one is in the center, another is in the upper left corner. Besides, no fading happens. Also i have three modes: view, edit, new - and when i open my panel it should show either "Create new..." or "Edit..." in the header and actually it shows but not in the header as the latter isn't rendered at all though it should, because i set proper mode in action before opening this modal panel. Besides it works fine on all other pages i've made and there are tens of such pages in my application. I can't understand what's wrong here. The only way to fix it is to remove <a4j:keepAlive/> from the page that is very strange, imho. I'm not sure if code will be usefull here as it works fine everywhere in my application but this only case. So if you put it on your page it will probably work without problems. My only question is: are there any hidden or rare problems in interaction of these two elements (<rich:modalPanel> and <a4j:keepAlive>)? Or shall i spent another two or three days searching for some wrong comma, parenthesis or whatever in my code? :) For most curious. Panel itself: <!-- there's no outer form --> <rich:modalPanel id="panel" autosized="true" minWidth="300" minHeight="200"> <f:facet name="header"> <h:panelGroup id="panelHeader"> <h:outputText value="#{msg.new_smth}" rendered="#{MbSmth.newMode}"/> <h:outputText value="#{msg.edit_smth}" rendered="#{MbSmth.editMode}"/> </h:panelGroup> </f:facet> <h:panelGroup id="panelDiv"> <h:form > <!-- fields and buttons --> </h:form> </h:panelGroup> </rich:modalPanel> One of the buttons that open panel: <a4j:commandButton id="addBtn" reRender="panelHeader, panelDiv" value="#{form.add}" oncomplete="#{rich:component('panel')}.show()" action="#{MbSmth.add}" image="create.gif"/> Action invoked on button click: public void add() { curMode = NEW_MODE; // initial mode is VIEW_MODE newSmth = new Smth(); } Mode check: public boolean isNewMode() { return curMode == NEW_MODE; } public boolean isEditMode() { return curMode == EDIT_MODE; }

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  • comparing two angles

    - by Elazar Leibovich
    Given four points in the plane, A,B,X,Y, I wish to determine which of the following two angles is smaller ?ABX or ?ABY. I'd rather not use cos or sqrt, in order to preserve accuracy. In the case where A=(-1,0),B=(0,0), I can compare the two angles ?ABX and ?ABY, by calculating the dot product of the vectors X,Y, and watch it's sign. What I can do in this case is: Determine whether or not ABX turns right or left If ABX turns left check whether or not Y and A are on the same side of the line on segment BX. If they are - ?ABX is a smaller than ABY. If ABX turns right, then Y and A on the same side of BX means that ?ABX is larger than ?ABY. But this seems too complicated to me. Any simpler approach?

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  • Wireless Network Disappearing From Available Networks (Windows 7)

    - by PeteDaMeat
    I have been using Windows 7 with a BT Voyager wireless adapter to connect to my home wireless network for around the last 6 months or so and until recently have experienced no problems. However, over the last couple of days Windows has been unable to connect to the network and the network name is no longer visible in the list of available wireless networks. The only way I have got round the problem is to reboot the NetGear router and to change the SSID to a network name which has not already been used. I do not believe the problem is with the router as my mobile phone can connect to it without any problems. The BT Voyager wireless adapter detects all other available networks so I presume this is a Windows 7 issue as it seems to occur when the PC is rebooted. This problen has happened twice in the last 2 days and is becoming extremely annoying. Does anyone have any suggestions?

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  • How reliable is HTTP compression using gzip?

    - by Liam
    YSlow has suggested that I use HTTP compression to improve the performance of my site. However, as noted by Yahoo that are some problems. There are known issues with browsers and proxies that may cause a mismatch in what the browser expects and what it receives with regard to compressed content. Fortunately, these edge cases are dwindling as the use of older browsers drops off. The Apache modules help out by adding appropriate Vary response headers automatically. I understand that the most common problem occurs with IE6 behind a proxy. But how common are these problems today? To quantify it, roughly what percentage of web users experience bugs with HTTP compression?

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  • How do I remove those rotation artefacts from my CATiledLayer?

    - by Felix
    Hello all, I have a CATiledLayer into which I render content in the following method - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx I used the QuartzDemo code to draw a pattern. This works very well until I apply a rotation transform to the layer's parentLayer (a UIView): rotated: These zigzag artefacts become worse when I start drawing lines and texts into the CATiledLayer. I applied the transform as follows (I also tried using an affine transform on the view itself): self.containerView.layer.transform = CATransform3DMakeRotation(angleRadians, 0.0f, 0.0f, 1.0f); I transform the containerView rather than the layer itself, as I have several layers in that view that I would like to rotate at the same time without changing the relative positions. I did not have problems when rotating UIImageViews in the past. Is there a way that I can rotate the CATiledLayer without these problems? Any help would be greatly appreciated. Yours, Felix

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  • How to create a container that holds different types of function pointers in C++?

    - by Alex
    I'm doing a linear genetic programming project, where programs are bred and evolved by means of natural evolution mechanisms. Their "DNA" is basically a container (I've used arrays and vectors successfully) which contain function pointers to a set of functions available. Now, for simple problems, such as mathematical problems, I could use one type-defined function pointer which could point to functions that all return a double and all take as parameters two doubles. Unfortunately this is not very practical. I need to be able to have a container which can have different sorts of function pointers, say a function pointer to a function which takes no arguments, or a function which takes one argument, or a function which returns something, etc (you get the idea)... Is there any way to do this using any kind of container ? Could I do that using a container which contains polymorphic classes, which in their turn have various kinds of function pointers? I hope someone can direct me towards a solution because redesigning everything I've done so far is going to be painful.

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  • Dock Panel component for .NET that allows docking inside tab-pages?

    - by Lasse V. Karlsen
    I want to build a user-interface that, for historical reasons, has a lot of "columns" of information. Many of these aren't relevant for all users in all cases, so I thought I'd look at dock panels to allow the users to hide or rearrange the columns according to their job scenario. This is Winforms in .NET 3.5. As such, I'd like the following: Have tab-pages in the main form Each tab-page can have dock-panels docked into them Dock-panels should be movable from one tab-page to another I've tried the following component packages so far without luck: Telerik Allows me to dock inside a tab-page, but dock-panels can't move from one tab-page to another. When attempting to drop a floating panel onto a different tab-page than the one it came from, it appears the dock will succeed, but when dropped it is docked on its owner container. Divelements SandDoc Same problems as with Telerik. DevExpress XtraBars Same problems as with Telerik. Basically, does anyone know of any such component (package) that would allow me to do what I want?

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  • How important is W3C XHTML/CSS validation when finalizing work?

    - by Andrew G. Johnson
    Even though I always strive for complete validation these days, I often wonder if it's a waste of time. If the code runs and it looks the same in all browsers (I use browsershots.org to verify) then do I need to take it any further or am I just being overly anal? What level do you hold your code to when you create it for: a) yourself b) your clients P.S. Jeff and company, why doesn't stack overflow validate? :) EDIT: Some good insights, I think that since I've been so valid-obsessed for so long I program knowing what will cause problems and what won't so I'm in a better position than people who create a site first and then "go back and fix the validation problems" I think I may post another question on stack overflow; "Do you validate as you go or do you finish and then go back and validate?" as that seems to be where this question is going

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  • Why GWT? Advantages and Trade-Offs of Using This RIA Framework

    - by prometheus
    I'm new to stackoverflow and have been reading through a bunch of the "highest voted" questions for GWT. Several of these questions talk about the pitfalls or problems with GWT. In the articles: Which Javascript framework (jQuery vs Dojo vs … )? and Biggest GWT Pitfalls?, some posters seem to suggest that GWT is not lightweight enough or that there are better alternatives that may be used. Do most of you feel that there are problems with GWT that have not been fixed with GWT 2.0 -- which would make you inclined to suggest using a simpler framework for a new project? To some extent, shouldn't GWT be somewhat future-proof (since you don't have to worry about it changing drastically from release to release and since it is backed by Google)? I realize that the answer to this question depends greatly upon what you want to do or what you wish to make. I am looking at this from the perspective of starting a new web application that will eventually be used by millions of users.

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  • Non-interactive command-line FTP client alternative to weex

    - by Halfgaar
    Hi, I'm looking for a good non-interactive, command line FTP client to be run from a Rakefile. Like Weex, but better. Weex has different problems (for me): It stores its config file in my home dir. I want the FTP config to be part of my project and weex doesn't have a --config-file option or something. The behavior of ignoring files seems to be completely buggy. It doesn't remove files which it should, it doesn't let me specify relative paths, even though I do it according to the man page's instructions, etc. I've been struggling with it for an hour now and it is just completely inexplicable. I tried running rsync over FTPFS/FUSE, but that is dead slow because FTP doesn't store mtimes, which makes rsync diff every file. Plus, there are some refresh problems and other bugs that cause access failure (http://bugs.gentoo.org/208168). I'm stuck with FTP, unfortunately. Any help is appreciated.

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  • Polygon area calculation using Latitude and Longitude generated from Cartesian space and a world fil

    - by Heath
    Given a series of GPS coordinate pairs, I need to calculate the area of a polygon (n-gon). This is relatively small (not larger than 50,000 sqft). The geocodes are created by applying an affine transform with data from a world file. I have tried to use a two step approach by doing converting the geocodes to cartesian coordinates: double xPos = (lon-lonAnchor)*( Math.toRadians( 6378137 ) )*Math.cos( latAnchor ); double yPos = (lat-latAnchor)*( Math.toRadians( 6378137 ) ); then I use a cross product calculation to determine the area. The issue is that the results are a bit off in accuracy (around 1%). Is there anything I can look into to improve this? Thanks.

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  • Mobile Safari Geolocation API Issues

    - by sph
    Hi, since Mobile Safari's Geolocation API should be an implementation of the W3C Geolocation API I found some bugs. I was wondering if anybody noticed the same. As specified in the W3C Geolocation API the PositionCallback returns a Position object, which contains a Coordinates object. In this object all attributes are of type double. Using navigator.geolocation.getCurrentPosition and checking the Position object in the successCallback the accuracy attribute is always an object, but should be a double. The heading attribute is always -1 when testing in the iPhone simulator, but should be null or between 0 and 360. 2. Setting the options parameter for navigator.geolocation.watchPosition or navigator.geolocation.getCurrentPosition as specified in the W3C Geolocation API has no effect. No matter what is set as the timeout value, the win callback is called every 10 seconds. For example setting the timeout=1000 should immediately call either the successCallback or errorCallback. Thanks

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  • How does the momentum/inertial scroll work with the Magic Mouse on NSScrollView?

    - by jbrennan
    When you scroll with the newer Apple Magic Mouse (at least on 10.6, I can't confirm any previous Mac OS) you get inertial scroll like scrolling on iPhone (that is, after a flick of the finger to scroll, it doesn't abruptly stop, but instead gradually slows down). This behaviour is "for free" with all NSScrollViews, it would appear. There are exceptional cases, such as Tweetie for Mac (I've heard Tweetie was written with a custom Table View class that works akin to how UITableView works on iPhone). My question is, how do the scroll views know how to do this inertial scrolling? My guess is the mouse [driver] repeatedly sends scroll events with a dampening scroll magnitude (or something like that) over the scroll period. But I'm not really sure how it works. I am having some scrolling problems in my scrollview class and I'm trying to figure out why (obviously we don't have the source code to Tweetie to see why it doesn't get the proper scrolling), but just trying to better understand how it works in order to fix my own problems.

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  • Searches (and general querying) with HBase and/or Cassandra (best practices?)

    - by alexeypro
    I have User model object with quite few fields (properties, if you wish) in it. Say "firstname", "lastname", "city" and "year-of-birth". Each user also gets "unique id". I want to be able to search by them. How do I do that properly? How to do that at all? My understanding (will work for pretty much any key-value storage -- first goes key, then value) u:123456789 = serialized_json_object ("u" as a simple prefix for user's keys, 123456789 is "unique id"). Now, thinking that I want to be able to search by firstname and lastname, I can save in: f:Steve = u:384734807,u:2398248764,u:23276263 f:Alex = u:12324355,u:121324334 so key is "f" - which is prefix for firstnames, and "Steve" is actual firstname. For "u:Steve" we save as value all user id's who are "Steve's". That makes every search very-very easy. Querying by few fields (properties) -- say by firstname (i.e. "Steve") and lastname (i.e. "l:Anything") is still easy - first get list of user ids from "f:Steve", then list from "l:Anything", find crossing user ids, an here you go. Problems (and there are quite a few): Saving, updating, deleting user is a pain. It has to be atomic and consistent operation. Also, if we have size of value limited to some value - then we are in (potential) trouble. And really not of an answer here. Only zipping the list of user ids? Not too cool, though. What id we want to add new field to search by. Eventually. Say by "city". We certainly can do the same way "c:Los Angeles" = ..., "c:Chicago" = ..., but if we didn't foresee all those "search choices" from the very beginning, then we will have to be able to create some night job or something to go by all existing User records and update those "c:CITY" for them... Quite a big job! Problems with locking. User "u:123" updates his name "Alex", and user "u:456" updates his name "Alex". They both have to update "f:Alex" with their id's. That means either we get into overwriting problem, or one update will wait for another (and imaging if there are many of them?!). What's the best way of doing that? Keeping in mind that I want to search by many fields? P.S. Please, the question is about HBase/Cassandra/NoSQL/Key-Value storages. Please please - no advices to use MySQL and "read about" SELECTs; and worry about scaling problems "later". There is a reason why I asked MY question exactly the way I did. :-)

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  • Are we asking too much of transactional memory?

    - by Carl Seleborg
    I've been reading up a lot about transactional memory lately. There is a bit of hype around TM, so a lot of people are enthusiastic about it, and it does provide solutions for painful problems with locking, but you regularly also see complaints: You can't do I/O You have to write your atomic sections so they can run several times (be careful with your local variables!) Software transactional memory offers poor performance [Insert your pet peeve here] I understand these concerns: more often than not, you find articles about STMs that only run on some particular hardware that supports some really nifty atomic operation (like LL/SC), or it has to be supported by some imaginary compiler, or it requires that all accesses to memory be transactional, it introduces type constraints monad-style, etc. And above all: these are real problems. This has lead me to ask myself: what speaks against local use of transactional memory as a replacement for locks? Would this already bring enough value, or must transactional memory be used all over the place if used at all?

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  • Visualize compiler warnings

    - by christoffer
    I'm looking for a way to visualize compiler warnings and remarks, by annotating or otherwise showing which lines cause a report. This is much like a modern IDE like NetBeans or Eclipse already does, but I'd like to take output from several compilers (and other static code analysis tools) at once, and create one single annotation in order to get a better overview. The rationale is that we've seen some problems go completely undetected by, say, Visual Studio 2005, but accurately detected with a proprietary ARM compiler, and vice versa. Cross-referencing warnings could potentially locate problems better, but doing so completely manually is infeasible. Have you heard of such a tool? Could an open-source IDE like Eclipse be extended to use several compilers at once, or has it already been done?

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  • Memory footprint of a parsed XML file in Classic ASP?

    - by Pete Duncanson
    Anyone know of a way to find out the amount of memory/size of a XMLDocument once it has parsed a XML file? I've been doing "beer mat" calculations so far but have been asked to come up with some more legit numbers through monitoring some how. I need to create about 1500 XML files (via FreeThreadedXMl-DOM object), which verge between 3-9K in size and store them in Application vars but our SysAdmin is worried about us gobbling up too much memory. Other than the crude method of booting up a fresh IIS instance and then loading everything in and monitoring before and after memory usage in Task Manager I can't think of a way of doing it with a bit more accuracy.

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  • .Net SvcUtil: attributes must be optional

    - by Michel van Engelen
    Hi, I'm trying to generate C# code classes with SvcUtil.exe instead of Xsd.exe. The latter is giving me some problems. Command line: SvcUtil.exe myschema.xsd /dconly /ser:XmlSerializer Several SvcUtil problems are described and solved here: http://blog.shutupandcode.net/?p=761 One problem I can't solve is this one: Error: Type 'DatafieldDescription' in namespace '' cannot be imported. Attributes must be optional and from namespace 'http://schemas.microsoft.com/2003/10/Seri alization/'. Either change the schema so that the types can map to data contract types or use ImportXmlType or use a different serializer. ' I changed <xs:attribute name="Order" use="required"> to <xs:attribute name="Order" use="optional"> and <xs:attribute name="Order"> But the error remains. Is it possible to use attributes, or do I have to delete them all (in that case, this excercition is over)?

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