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  • Should I use IDisposable for purely managed resources?

    - by John Gietzen
    Here is the scenario: I have an object called a Transaction that needs to make sure that only one entity has permission to edit it at any given time. In order to facilitate a long-lived lock, I have the class generating a token object that can be used to make the edits. You would use it like this: var transaction = new Transaction(); using (var tlock = transaction.Lock()) { transaction.Update(data, tlock); } Now, I want the TransactionLock class to implement IDisposable so that its usage can be clear. But, I don't have any unmanaged resources to dispose. however, the TransctionLock object itself is a sort of "unmanaged resource" in the sense that the CLR doesn't know how to properly finalize it. All of this would be fine and dandy, I would just use IDisposable and be done with it. However, my issue comes when I try to do this in the finalizer: ~TransactionLock() { this.Dispose(false); } I want the finalizer to release the transaction from the lock, if possible. How, in the finalizer, do I detect if the parent transaction (this.transaction) has already been finalized? Is there a better pattern I should be using? The Transaction class looks something like this: public sealed class Transaction { private readonly object lockMutex = new object(); private TransactionLock currentLock; public TransactionLock Lock() { lock (this.lockMutex) { if (this.currentLock != null) throw new InvalidOperationException(/* ... */); this.currentLock = new TransactionLock(this); return this.currentLock; } } public void Update(object data, TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); // ... } } internal void ValidateLock(TransactionLock tlock) { if (this.currentLock == null) throw new InvalidOperationException(/* ... */); if (this.currentLock != tlock) throw new InvalidOperationException(/* ... */); } internal void Unlock(TransactionLock tlock) { lock (this.lockMutex) { this.ValidateLock(tlock); this.currentLock = null; } } }

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  • Suggestions for VS+Resharper keyboard shortcuts on a Mac

    - by John Miller
    I just upgraded to a Macbook Pro as my development machine but still primarily develop .Net applications with Visual Studio and Resharper (via VMWare Fusion). By far, the biggest obstacle I'm running into is getting used to the keyboard layout change (ex. not being able to do ALT-Insert). Do any of you Windows-on-Mac veterans have any suggestions on how to ease the pain of transitioning (without moving to an external keyboard)? Are you changing mappings via VMWare's keyboard preferences? Or are you using something like AutoHotkey? Any other windows development tips for a Mac newb?

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  • generate php code from wsdl

    - by John Stewart
    I have a bunch of webservices that I need to write PHP clients for. Now I can manually write wrappers for each of the WSDL files but i wanted to see if there is a tool that can help me by generating the wrappers in PHP. Any idea if there are any tools that do this? Thanks

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  • Null-free "maps": Is a callback solution slower than tryGet()?

    - by David Moles
    In comments to "How to implement List, Set, and Map in null free design?", Steven Sudit and I got into a discussion about using a callback, with handlers for "found" and "not found" situations, vs. a tryGet() method, taking an out parameter and returning a boolean indicating whether the out parameter had been populated. Steven maintained that the callback approach was more complex and almost certain to be slower; I maintained that the complexity was no greater and the performance at worst the same. But code speaks louder than words, so I thought I'd implement both and see what I got. The original question was fairly theoretical with regard to language ("And for argument sake, let's say this language don't even have null") -- I've used Java here because that's what I've got handy. Java doesn't have out parameters, but it doesn't have first-class functions either, so style-wise, it should suck equally for both approaches. (Digression: As far as complexity goes: I like the callback design because it inherently forces the user of the API to handle both cases, whereas the tryGet() design requires callers to perform their own boilerplate conditional check, which they could forget or get wrong. But having now implemented both, I can see why the tryGet() design looks simpler, at least in the short term.) First, the callback example: class CallbackMap<K, V> { private final Map<K, V> backingMap; public CallbackMap(Map<K, V> backingMap) { this.backingMap = backingMap; } void lookup(K key, Callback<K, V> handler) { V val = backingMap.get(key); if (val == null) { handler.handleMissing(key); } else { handler.handleFound(key, val); } } } interface Callback<K, V> { void handleFound(K key, V value); void handleMissing(K key); } class CallbackExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; private Callback<String, String> handler; public CallbackExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); handler = new Callback<String, String>() { public void handleFound(String key, String value) { found.add(key + ": " + value); } public void handleMissing(String key) { missing.add(key); } }; } void test() { CallbackMap<String, String> cbMap = new CallbackMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; cbMap.lookup(key, handler); } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } Now, the tryGet() example -- as best I understand the pattern (and I might well be wrong): class TryGetMap<K, V> { private final Map<K, V> backingMap; public TryGetMap(Map<K, V> backingMap) { this.backingMap = backingMap; } boolean tryGet(K key, OutParameter<V> valueParam) { V val = backingMap.get(key); if (val == null) { return false; } valueParam.value = val; return true; } } class OutParameter<V> { V value; } class TryGetExample { private final Map<String, String> map; private final List<String> found; private final List<String> missing; public TryGetExample(Map<String, String> map) { this.map = map; found = new ArrayList<String>(map.size()); missing = new ArrayList<String>(map.size()); } void test() { TryGetMap<String, String> tgMap = new TryGetMap<String, String>(map); for (int i = 0, count = map.size(); i < count; i++) { String key = "key" + i; OutParameter<String> out = new OutParameter<String>(); if (tgMap.tryGet(key, out)) { found.add(key + ": " + out.value); } else { missing.add(key); } } System.out.println(found.size() + " found"); System.out.println(missing.size() + " missing"); } } And finally, the performance test code: public static void main(String[] args) { int size = 200000; Map<String, String> map = new HashMap<String, String>(); for (int i = 0; i < size; i++) { String val = (i % 5 == 0) ? null : "value" + i; map.put("key" + i, val); } long totalCallback = 0; long totalTryGet = 0; int iterations = 20; for (int i = 0; i < iterations; i++) { { TryGetExample tryGet = new TryGetExample(map); long tryGetStart = System.currentTimeMillis(); tryGet.test(); totalTryGet += (System.currentTimeMillis() - tryGetStart); } System.gc(); { CallbackExample callback = new CallbackExample(map); long callbackStart = System.currentTimeMillis(); callback.test(); totalCallback += (System.currentTimeMillis() - callbackStart); } System.gc(); } System.out.println("Avg. callback: " + (totalCallback / iterations)); System.out.println("Avg. tryGet(): " + (totalTryGet / iterations)); } On my first attempt, I got 50% worse performance for callback than for tryGet(), which really surprised me. But, on a hunch, I added some garbage collection, and the performance penalty vanished. This fits with my instinct, which is that we're basically talking about taking the same number of method calls, conditional checks, etc. and rearranging them. But then, I wrote the code, so I might well have written a suboptimal or subconsicously penalized tryGet() implementation. Thoughts?

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  • R: How can I use apply on rows of a data.frame and get out $column_name?

    - by John
    I'm trying to access $a using the following example: df<-data.frame(a=c("x","x","y","y"),b=c(1,2,3,4)) > df a b 1 x 1 2 x 2 3 y 3 4 y 4 test_fun <- function (data.frame_in) { print (data.frame_in[1]) } I can now access $a if I use an index for the first column: apply(df, 1, test_fun) a "x" a "x" a "y" a "y" [1] "x" "x" "y" "y" But I cannot access column $a with the $ notation: error: "$ operator is invalid for atomic vectors" test_fun_2 <- function (data.frame_in) { print (data.frame_in$a) } >apply(df, 1, test_fun_2) Error in data.frame_in$a : $ operator is invalid for atomic vectors Is this not possible?

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  • Lamda expression will not compile

    - by John Soer
    I am very confused I have this lamba expression tvPatientPrecriptionsEntities.Sort((p1, p2) => p1.MedicationStartDate.Value.CompareTo(p2.MedicationStartDate.Value)); Visual studio will not compile it and complains about syntax. I converted the lamba expression to an anonymous delegate as so tvPatientPrecriptionsEntities.Sort( delegate(PatientPrecriptionsEntity p1, PatientPrecriptionsEntity p2) { return p1.MedicationStartDate.Value.CompareTo(p2.MedicationStartDate.Value); } ); and it works fine. The project is uses the .net 3.5 framework and I have a reference to system.linq.

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  • How to make dynamic object?

    - by John
    I am using the XmlSerializer like this, XmlSerializer xs = new XmlSerializer(typeof(myType)); Now I have 5 different "myType". How do I pass the specific type dynamically so I don't have to repeat the same code 5 times? Thanks

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  • Is there a Firebug console -vsdoc.js?

    - by David Murdoch
    If not, does anyone care to write one? I would do it myself...but I don't have time right now...maybe next week (unless someone beats me to it). If you are bored and want to compile the vsdoc: Here is the Firebug API. Here is a blog post about the format for VS doc comments for intellisense. Here is an example vsdoc (jquery-1.4.1-vsdoc.js). I created the following because I kept typing cosnole instead of console. You can use it as a starting point (ish). console = { /// <summary> /// 1: The javascript console /// </summary> /// <returns type="Object" /> }; console.log = function (object) { /// <summary> /// Write to the console's log /// </summary> /// <returns type="null" /> /// <param name="object" type="Object"> /// Write the object to the console's log /// </param> };

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  • F# - core benefits

    - by David Neale
    Since the release of VS 2010 I've seen F# more strongly advertised by Microsoft. What are the core benefits of using this language? What problems does it most naturally lend itself to? What is the learning curve like?

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  • Java desktop app: How to maximize tray application when hotkey pressed?

    - by David
    I need to write a program that, when minimized, lives in the System Tray, and I'll use Java 6's SystemTray API to do that. How can I make that application comes to the foreground when the user presses some hotkey? For example, the app is running but minimized. When the user presses CTRL-SHIFT-Y or something (or, like Google Desktop's search, CTRL twice) and the application is maximized. EDIT: I know about how to bring a Java window to the foreground. I'm asking more specifically about how to make a running Java app listen for a hotkey.

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  • Automatically number items in a wpf listbox

    - by evan
    I have a person class with two properties, Name an Age. I know how to use databinding to display a collection of person in a wpf list box and how to modify the listitemtemplate to customize how each person is displayed. Now I'd like to number each person on the list according to the order they appear on the list (which could change as the the items were sorted via name or age in the display). Is there a way to do that with the item template so instead of having a list like Rob - 14 John - 56 Suzy - 32 it would be 1) Rob - 14 2) John - 56 3) Suzy - 32 Basically i'd like to do something like: <ListView.ItemTemplate> <DataTemplate> <WrapPanel> **<TextBlock Text="{Binding CurrentPositionInList}" />** <TextBlock Text="{Binding Path=Name}" /> <TextBlock Text="{Binding Path=Age}" /> </WrapPanel> </DataTemplate> Thanks in advance!

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  • NSURLErrorDomain error -3001

    - by David Schiefer
    Hi, I'm trying to download a file from the internet, but I get the error -3001 back. I've been searching through google but the error doesn't appear on any website, so i have no idea what it means. Can anyone tell me what the error code "NSURLErrorDomain error -3001" means? Thanks

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  • Model a Zero or One to Many Relationship

    - by John
    How should I model a zero or one to a many relationship in the database? For example, a user record may or may not have a parent. So should my user table have a t_user.parent_id or should I have an associative table called t_user_hierarchy with the columns t_user_hierarchy.parent_id and t_user_hierarchy.user_id?

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  • Cannot access implict object from within method in custom JSP tag file

    - by David Hamilton
    I'm attempting to create a custom jsp tag. Everything is working fine, except for the fact that I the request seems to be out-of-scope for my custom function. Here is the relevant bit from the .tag file: <%! private String process(String age, BigDecimal amount) { //Attempting to access request here results in an compile time error trying to: String url=request.getURL; } %> I'm very new to JSP so I'm sure I'm missing something obvious..but I can't seem to figure out what. Any help is appreciated.

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  • Did I implement clock drift properly?

    - by David Titarenco
    I couldn't find any clock drift RNG code for Windows anywhere so I attempted to implement it myself. I haven't run the numbers through ent or DIEHARD yet, and I'm just wondering if this is even remotely correct... void QueryRDTSC(__int64* tick) { __asm { xor eax, eax cpuid rdtsc mov edi, dword ptr tick mov dword ptr [edi], eax mov dword ptr [edi+4], edx } } __int64 clockDriftRNG() { __int64 CPU_start, CPU_end, OS_start, OS_end; // get CPU ticks -- uses RDTSC on the Processor QueryRDTSC(&CPU_start); Sleep(1); QueryRDTSC(&CPU_end); // get OS ticks -- uses the Motherboard clock QueryPerformanceCounter((LARGE_INTEGER*)&OS_start); Sleep(1); QueryPerformanceCounter((LARGE_INTEGER*)&OS_end); // CPU clock is ~1000x faster than mobo clock // return raw return ((CPU_end - CPU_start)/(OS_end - OS_start)); // or // return a random number from 0 to 9 // return ((CPU_end - CPU_start)/(OS_end - OS_start)%10); } If you're wondering why I Sleep(1), it's because if I don't, OS_end - OS_start returns 0 consistently (because of the bad timer resolution, I presume). Basically, (CPU_end - CPU_start)/(OS_end - OS_start) always returns around 1000 with a slight variation based on the entropy of CPU load, maybe temperature, quartz crystal vibration imperfections, etc. Anyway, the numbers have a pretty decent distribution, but this could be totally wrong. I have no idea.

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  • Jetspeed 2.2 Nest or render one portlet inside another

    - by David Just
    I have a requirement to build an extensible wizard in a portlet. This wizard will list components that are installed and forward the user to a sub-wizard that is component specific. The requirement is that the components are to be developed by other people and dynamically plugged into this wizard (Jetspeed reboot is okay). I would like to be able to define the components as portlets themselves who's content is rendered into the primary portlet. Has anybody ever done something like this?

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  • How to Override a private set property

    - by David
    Hi, Im using the Microsoft.Office.Interop.MSProject.Resource assembly which has a "UniqueID" property, it has a get but not set. How can I actually set a value? An example would be very much appreciated. --Update-- Ok I can get the value for a property "Name" and set, but Im intersted in the "UniqueId" property that does not have a public set (get only): int ii = (int)resource.GetType().InvokeMember("UniqueID", BindingFlags.GetProperty, null, resource, new object[] { }); resource.GetType().InvokeMember("UniqueID", BindingFlags.SetProperty, null, resource, new object[] {iUid,}); I get the following error {"Number of parameters specified does not match the expected number."} anyway for me to work out how many paramters it needs?

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  • Getting specific values with regex [JAVA, ANDROID]

    - by David
    I need to knowingly isolate each row of the vcard and get its value. For instance, I want to get "5555" from X-CUSTOMFIELD. So far, my thoughts are: "X-CUSTOMFIELD;\d+" I have been looking at some tutorials and I am a little confused with what function to use? What would my regex above return? Would it give me the whole line or just the numerical part (5555)? I was thinking I i get the whole row, I can use substring to get the digits? BEGIN:VCARD VERSION:2.1 N:Last;First; FN:First Last TEL;HOME;VOICE:111111 TEL;MOBILE;VOICE:222222 X-CUSTOMFIELD;5555 END:VCARD

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  • StackPanel position

    - by John Espinosa
    How can I find the position of a StackPanel after it has been animated? I have a button which slides the stackpanel to the left. But if I want it to slide to the left again, the animation does not work.

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  • Jquery autocomplete for input form, using Textpattern category list as a source

    - by John Stephens
    I'm using the Textpattern CMS to build a discussion site-- I have a firm grasp of XHTML and CSS, as well as Textpattern's template language, but PHP and Javascript are a bit beyond my cunning. On the input form to begin a new topic, users need to select a category from a list of over 5,000 options. Using the HTML select-type input element is very unwieldy, but it works. I would like to use some kind of Javascript magic to display a text-type input element that will read user input and display matches or autocomplete from the available categories, passing the required option's value into the appropriate database field. I've seen several autocomplete plugins for jquery, but the instructions presuppose that you understand how Javascript works. As I mentioned above, it's easy for me to generate the category list as a select-type input element, and I can hide that element using CSS. Is it possible to control select-list input using an autocomplete mechanism in a text-type input element? How would I do that?

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  • ActionScript: Determine wether superclass implements a particular interface?

    - by David Wolever
    Is there any non-hacky way to determine wether a class' superclass implements a particular interface? For example, assume I've got: class A extends EventDispatcher implements StuffHolder { private var myStuff = someKindOfStuff; public function getStuff():Array { if (super is StuffHolder) // <<< this doesn't work return super['getStuff']().concat([myStuf]); return [myStuff]; } class B extends A { private var myStuff = anotherKindOfStuff; } How could I perform that super is StuffHolder test in a way that, well, works? In this case, it always returns true.

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