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  • How to assign a value of a property to a var ONLY if the object isn't null

    - by Blankman
    In my code, is there a shorthand that I can use to assign a variable the value of a object's property ONLY if the object isn't null? string username = SomeUserObject.Username; // fails if null I know I can do a check like if(SomeUserObject != null) but I think I saw a shorthand for this kind of test. I tried: string username = SomeUserObject ?? "" : SomeUserObject.Username; But that doesn't work.

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  • Creating and releasing objects in the same method, while using self as delegate

    - by user200341
    In objective-c you are responsible for releasing objects you allocate, but what happens when you allocate an object in a method, assign self as the objects delegate, and then release the object. The callbacks from the newly created (and released) object fails at this point, or rather, doesn't happen. - (void)doSomething { MyObj *myObj = [[MyObj alloc] init]; myObj.delegate = self; [myObj performOperation]; [myObj release]; } - (void)callbackMethodFromMyObj:(NSString *)message { NSLog(message); } I can't release the object until the callback has occurred, and I can't avoid releasing the object in the same method that creates it (because it exists outside the scope). One way of doing it would be to pass the object along in the call-back and release it in the callback, but is this the right way to go about this?

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  • Typeclass instances for unnamed types in Scala

    - by ncreep
    How would one encode the following constraint in Scala (pseudocode)? def foo(x: T forSome { type T has a Numeric[T] instance in scope }) = { val n= implicitly[...] // obtain the Numeric instance for x n.negate(x) // and use it with x } In words: I need a type class instance for my input argument, but I don't care about the argument's type, I just need to obtain the instance and use it on my argument. It doesn't have to be an existential type, but I need to avoid type parameters in the def's signature. Thanks.

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  • Get SEO friendly URLS with Rails without method_missing?

    - by tesmar
    Hi all, Currently we are using method_missing to catch for calls to SEO friendly actions in our controllers rather than creating actions for every conceivable value for a variable. What we want are URLS like this: /students/BobSmith and NOT /students/show/342 IS there a cleaner solution than method_missing? Thank you!

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  • C# Event routing in code behind

    - by Nate
    I'm building a WPF MVVM-ish application. I want to be able to display an event log containing items in a collection that exists in my viewmodel. I want any of the objects in the model to be able to add data to the event log. Therefore every object needs to be able to pass data back to one central collection for databinding in the view. I could implement an event in every one of my data classes and manually pass the events up the object heirarchy but this seems super clumsy. On the visual tree a Routed Event would take care of this, is there some equivelent in the model scope? Any other ideas?

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  • Persistence scheme & state data for low memory situations (iphone)

    - by Robin Jamieson
    What happens to state information held by a class's variable after coming back from a low memory situation? I know that views will get unloaded and then reloaded later but what about some ancillary classes & data held in them that's used by the controller that launched the view? Sample scenario in question: @interface MyCustomController: UIViewController { ServiceAuthenticator *authenticator; } -(id)initWithAuthenticator:(ServiceAuthenticator *)auth; // the user may press a button that will cause the authenticator // to post some data to the service. -(IBAction)doStuffButtonPressed:(id)sender; @end @interface ServiceAuthenticator { BOOL hasValidCredentials; // YES if user's credentials have been validated NSString *username; NSString *password; // password is not stored in plain text } -(id)initWithUserCredentials:(NSString *)username password:(NSString *)aPassword; -(void)postData:(NSString *)data; @end The app delegate creates the ServiceAuthenticator class with some user data (read from plist file) and the class logs the user with the remote service. inside MyAppDelegate's applicationDidFinishLaunching: - (void)applicationDidFinishLaunching:(UIApplication *)application { ServiceAuthenticator *auth = [[ServiceAuthenticator alloc] initWithUserCredentials:username password:userPassword]; MyCustomController *controller = [[MyCustomController alloc] initWithNibName:...]; controller.authenticator = auth; // Configure and show the window [window addSubview:..]; // make everything visible [window makeKeyAndVisible]; } Then whenever the user presses a certain button, 'MyCustomController's doStuffButtonPressed' is invoked. -(IBAction)doStuffButtonPressed:(id)sender { [authenticator postData:someDataFromSender]; } The authenticator in-turn checks to if the user is logged in (BOOL variable indicates login state) and if so, exchanges data with the remote service. The ServiceAuthenticator is the kind of class that validates the user's credentials only once and all subsequent calls to the object will be to postData. Once a low memory scenario occurs and the associated nib & MyCustomController will get unloaded -- when it's reloaded, what's the process for resetting up the 'ServiceAuthenticator' class & its former state? I'm periodically persisting all of the data in my actual model classes. Should I consider also persisting the state data in these utility style classes? Is that the pattern to follow?

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  • home directory and .emacs file in Windows 7

    - by prosseek
    I installed emacs 23.3.1 in c:/emacs-23.3. Following the hints in this page, I updated the site-start.el to set HOME environment variable. (setenv "HOME" "c:/users/USER/emacs") And I made c:/users/USER/.emacs (like I did in unix/mac) to write the code for using slime, but it doesn't seem to start slime correctly. Is this a correct way of setting emacs in Windows 7? Where do I put the .emacs file?

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  • File size in Python server

    - by Anna
    We have server on Python and client + web service on Ruby. That works only if file from URL is less than 800 k. It seems like "socket.puts data" in a client works, but "output = socket.gets" - not. I think problem is in a Python part. For big files tests run "Connection reset by peer". Is it buffer size variable by default somewhere in a Python?

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  • java objects, shared variables

    - by raven
    hello, I have a simple question here. If I declare a variable inside an object which was made [declared] in the main class, like this: public static int number; ( usually I declare it like this : private int number; ) can it be used in a different object which was also made [declared] in the main class? btw I do not care about security atm, I just want to make something work, don't care about protection)

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  • Calculating Growth-Rates by applying log-differences

    - by mropa
    I am trying to transform my data.frame by calculating the log-differences of each column and controlling for the rows id. So basically I like to calculate the growth rates for each id's variable. So here is a random df with an id column, a time period colum p and three variable columns: df <- data.frame (id = c("a","a","a","c","c","d","d","d","d","d"), p = c(1,2,3,1,2,1,2,3,4,5), var1 = rnorm(10, 5), var2 = rnorm(10, 5), var3 = rnorm(10, 5) ) df id p var1 var2 var3 1 a 1 5.375797 4.110324 5.773473 2 a 2 4.574700 6.541862 6.116153 3 a 3 3.029428 4.931924 5.631847 4 c 1 5.375855 4.181034 5.756510 5 c 2 5.067131 6.053009 6.746442 6 d 1 3.846438 4.515268 6.920389 7 d 2 4.910792 5.525340 4.625942 8 d 3 6.410238 5.138040 7.404533 9 d 4 4.637469 3.522542 3.661668 10 d 5 5.519138 4.599829 5.566892 Now I have written a function which does exactly what I want BUT I had to take a detour which is possibly unnecessary and can be removed. However, somehow I am not able to locate the shortcut. Here is the function and the output for the posted data frame: fct.logDiff <- function (df) { df.log <- dlply (df, "code", function(x) data.frame (p = x$p, log(x[, -c(1,2)]))) list.nalog <- llply (df.log, function(x) data.frame (p = x$p, rbind(NA, sapply(x[,-1], diff)))) ldply (list.nalog, data.frame) } fct.logDiff(df) id p var1 var2 var3 1 a 1 NA NA NA 2 a 2 -0.16136569 0.46472004 0.05765945 3 a 3 -0.41216720 -0.28249264 -0.08249587 4 c 1 NA NA NA 5 c 2 -0.05914281 0.36999681 0.15868378 6 d 1 NA NA NA 7 d 2 0.24428771 0.20188025 -0.40279188 8 d 3 0.26646102 -0.07267311 0.47041227 9 d 4 -0.32372771 -0.37748866 -0.70417351 10 d 5 0.17405309 0.26683625 0.41891802 The trouble is due to the added NA-rows. I don't want to collapse the frame and reduce it, which would be automatically done by the diff() function. So I had 10 rows in my original frame and am keeping the same amount of rows after the transformation. In order to keep the same length I had to add some NAs. I have taken a detour by transforming the data.frame into a list, add the NAs, and afterwards transform the list back into a data.frame. That looks tedious. Any ideas to avoid the data.frame-list-data.frame class transformation and optimize the function?

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  • How to parse a date from an SSIS Excel filename

    - by user327045
    I want to use the foreach container to iterate through a folder matching something like: "Filename_MMYYYY.xls". That's easy enough to do; but I can't seem to find a way to parse the MMYYYY from the filename and add it to a variable (or something) that i can use as a lookup field for my DimDate table. It seems possible with a flat file data source, but not an excel connection. I'm using Visual Studio 2005. Please help!

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  • I need to cut a portion of a string in linux

    - by Abeed Salam
    I have a file in a folder like this: installer-x86_64-XXX.XX-diagnostic.run The XXX.XX is a version number and I need the version number only. How to do it in linux? I have this code: #!/bin/bash current_ver=$(find /mnt/builds/current -name '*.run'|awk -F/ '{print $NF}') So this gives me just the name of the file correctly (minus the location, which I dont want). But how do I only get the XXX.XX version number into a variable such as $version

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  • Using Django.test.client to check template vars

    - by scott
    I've got a view that I'm trying to test with the Client object. Can I get to the variables I injected into the render_to_response of my view? Example View: def myView(request): if request.method == "POST": # do the search return render_to_response('search.html',{'results':results},context_instance=RequestContext(request)) else: return render_to_response('search.html',context_instance=RequestContext(request) Test: c = Client() response = c.post('/school/search/', {'keyword':'beagles'}) # how do I get to the 'results' variable??

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  • Can a function defined in a bookmarklet be called from a page-level script?

    - by Soviut
    I have a bookmarklet that needs to open a new window/tab. In order to avoid the popup blocker, I need to call the window.open() method directly in the bookmarklet ie: at the browser-level. However, I want to keep the bookmarklet updatable by loading external Javascript files. To do this, the bookmarklet needs to append script nodes to the DOM. If i were to put window.open() code in one of these externally loaded scripts, the popup blocker would block it since its page-level. What I want to know is if I can create a wrapper function around window.open() in my bookmarklet, then call it from the externally loaded script? What is the scope and what are the permissions on a wrap such as this?

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  • VBA Range.Rows.Count giving unexpected results

    - by Jeffrey
    I have a Range variable that contains an address - $2:$2,$4:$205,$214:$214 - (3 groups of rows). I would like to get the count of all the rows in that range. However, range.Count gives me the count of all the cells (50,000~) and range.Rows.Count only return 1 - the count of all the rows in the first group. How do I get the count of all the rows Thanks

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  • Realtime MySQL search results on an advanced search page

    - by Andrew Heath
    I'm a hobbyist, and started learning PHP last September solely to build a hobby website that I had always wished and dreamed another more competent person might make. I enjoy programming, but I have little free time and enjoy a wide range of other interests and activities. I feel learning PHP alone can probably allow me to create 98% of the desired features for my site, but that last 2% is awfully appealing: The most powerful tool of the site is an advanced search page that picks through a 1000+ record game scenario database. Users can data-mine to tremendous depths - this advanced page has upwards of 50 different potential variables. It's designed to allow the hardcore user to search on almost any possible combination of data in our database and it works well. Those who aren't interested in wading through the sea of options may use the Basic Search, which is comprised of the most popular parts of the Advanced search. Because the advanced search is so comprehensive, and because the database is rather small (less than 1,200 potential hits maximum), with each variable you choose to include the likelihood of getting any qualifying results at all drops dramatically. In my fantasy land where I can wield AJAX as if it were Excalibur, my users would have a realtime Total Results counter in the corner of their screen as they used this page, which would automatically update its query structure and report how many results will be displayed with the addition of each variable. In this way it would be effortless to know just how many variables are enough, and when you've gone and added one that zeroes out the results set. A somewhat similar implementation, at least visually, would be the Subtotal sidebar when building a new custom computer on IBuyPower.com For those of you actually still reading this, my question is really rather simple: Given the time & ability constraints outlined above, would I be able to learn just enough AJAX (or whatever) needed to pull this one feature off without too much trouble? would I be able to more or less drop-in a pre-written code snippet and tweak to fit? or should I consider opening my code up to a trusted & capable individual in the future for this implementation? (assuming I can find one...) Thank you.

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  • Get smallest date for each element in access query

    - by skerit
    So I have a table containing different elements and dates. It basically looks like this: actieElement beginDatum 1 1/01/2010 1 1/01/2010 1 10/01/2010 2 1/02/2010 2 3/02/2010 What I now need is the smallest date for every actieElement. I've found a solution using a simple GROUP BY statement, but that way the query loses its scope and you can't change anything anymore. Without the GROUP BY statement I get multiple dates for every actieElement because certain dates are the same. I thought of something like this, but it also does not work as it would give the subquery more then 1 record: SELECT s1.actieElement, s1.begindatum FROM tblActieElementLink AS s1 WHERE (((s1.actieElement)=(SELECT TOP 1 (s2.actieElement) FROM tblActieElementLink s2 WHERE s1.actieElement = s2.actieElement ORDER BY s2.begindatum ASC)));

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  • conversion from C++ to C

    - by Dave
    Hi I am interested by converting some code from C++ to C (mostly because i need to use the library with/from other C program and other language) . C is a better gateway for that I am interested to replicate few C++ concept like inheritance for inst . Does anyone know good references or has already work on some similar issues. For inst how to deal with inheritance , adding new members variable/ methods to child class , ... Thx for your help

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