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  • What is the difference between using IDisposable vs a destructor in C#?

    - by j0rd4n
    When would I implement IDispose on a class as opposed to a destructor? I read this article, but I'm still missing the point. My assumption is that if I implement IDispose on an object, I can explicitly 'destruct' it as opposed to waiting for the garbage collector to do it. Is this correct? Does that mean I should always explicitly call Dispose on an object? What are some common examples of this?

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  • Would an array of SSD drives be able to succesfully substitute the system memory?

    - by Florin Mircea
    I watched a few videos trying to answer this. This video (youtube.com/watch?v=eULFf6F5Ri8) shows a bunch of guys stacking 24 SSD's reaching a peak of around 2GBps r/w. That's under the limit of the worst DDR3 in this list (memorybenchmark.net/write_ddr3_amd.html) - that shows DDR3 memory performance varying from 2.78 to 6.55 Gb per second, but that video is over 3 years old. This video (youtube.com/watch?v=27GmBzQWwP0) shows a more optimistic situation, but for PCI-E SSD drives: 5 drives peaking at around 4Gb. And this other video shows that stacking up more than 3 SSD's doesn't realistically offer a substantial added performance. This and the fact that in all benchmarks the drives act quite poorly when dealing with small files (5k file read/write averaging from 10MB to around 30-40MBps) as opposed to how native memory handles such files, seems to indicate a definite NO to this question. Also, the write life cycle is indeed limited and the drives might wear out quickly, as kindly pointed out by paddy. However, I wanted to get more opinions on this. Would it be possible to at least obtain current memory performance with SSD's in RAID 0? And if so, in what circumstances? I am assuming using this configuration with a Windows OS that has a memory pagefile resident to that stack of SSD's, thus making it very fast to work with.

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  • What is the difference between a restful route method for getting an index vs. creating a new object

    - by Jason
    According to rake routes, there's the same path for getting an index of objects as there is for creating a new object: cars GET /cars(.:format) {:controller=>"plugs", :what=>"car", :action=>"index"} POST /cars(.:format) {:controller=>"plugs", :what=>"car", :action=>"create"} Obviously, the HTTP verb is what distinguishes between them. I want the "create" version of the cars_path method, not the "index" version. My question is what route method do you invoke to choose the one you want? I'm telling cucumber what path to generate with this: when /the car plug preview page for "(.+)"/ cars_path(:action => :create, :method => :post) ...but it always chooses the "index" action, not "create". I've tried lots of combinations for the hash argument following cars_path and nothing changes it from choosing "index" instead of "create". I'll get an error like this: cars_url failed to generate from {:controller=>"plugs", :method=>:post, :what=>"car", :action=>"create"}, expected: {:controller=>"plugs", :what=>"car", :action=>"index"}, diff: {:method=>:post, :action=>"index"} (ActionController::RoutingError) This seems like a very simple question but I've had no luck googling for it, so could use some advice. Thanks.

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  • Difference in select for update of ... in Oracle Database 10g and 11g

    - by sax
    Hi, I found out that Oracle Database 10g and 11g treat the following PL/SQL block differently (I am using scott schema for convenience): DECLARE v_ename bonus.ename%TYPE; BEGIN SELECT b.ename INTO v_ename FROM bonus b JOIN emp e ON b.ename = e.ename JOIN dept d ON d.deptno = e.deptno WHERE b.ename = 'Scott' FOR UPDATE OF b.ename; END; / While in 10g (10.2) this code ends successfully (well NO_DATA_FOUND exception is raised but that is expected), in 11g (11.2) it raises exception "column ambiguously defined". And that is definitely not expected. It seems like it does not take into account table alias because I found out that when I change the column in FOR UPDATE OF e.empno (also does not work) to e.mgr (which is unique) it starts working. So is this some error in 11g? Any thoughts?

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  • Difference in css position IF/FF, how to solv my problem?

    - by Jason94
    Ive made some divs and it works as intended in firefox: http://yfrog.com/0y95240044p But not in internet explorer 8: http://yfrog.com/0obadpp Anyone have a tip? structure is like this: <div id="container"> <div id="imgContainer"> <div id="button"></div> </div> <div id="text">text</div> </div> imgContainer gets a image as background by some javascript magic.

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  • Does it make a difference in performance if I use self.fooBar instead of fooBar?

    - by mystify
    Note: I know exactly what a property is. This question is about performance. Using self.fooBar for READ access seems a waste of time for me. Unnecessary Objective-C messaging is going on. The getters typically simply pass along the ivar, so as long as it's pretty sure there will be no reasonable getter method written, I think it's perfectly fine to bypass this heavy guy. Objective-C messaging is about 20 times slower than direct calls. So if there is some high-performance-high-frequency code with hundreds of properties in use, maybe it does help a lot to avoid unnessessary objective-c messaging? Or am I wasting my time thinking about this?

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  • Passing NULL value

    - by FFXIII
    Hi. I use an instance of NSXMLParser. I store found chars in NSMutableStrings that are stored in an NSMutableDictionary and these Dicts are then added to an NSMutableArray. When I test this everything seems normal: I count 1 array, x dictionnaries and x strings. In a detailview controller file I want to show my parsed results. I call the class where everthing is stored but I get (null) returned. This is what I do (wrong): XMLParser.h @interface XMLParser : NSObject { NSMutableArray *array; NSMUtableDictionary *dictionary; NSSMutabletring *element; } @property (nonatomic, retain) NSMutableArray *array; @property (nonatomic, retain) NSMutableDictionary *dictionary; @property (nonatomic, retain) NSMutableString *element; XMLParser.m @synthesize array, dictionary, element; //parsing goes on here & works fine //so 'element' is filled with content and stored in a dict in an array //and released at the end of the file In my controller file I do this: controller.h @class XMLParser; @interface controller : UIViewController { XMLParser *aXMLParser; } @property (nonatomic, retain) XMLParser *aXMLParser; controller.m #import "XMLParser.h" @synthesize aXMLParser; - (void)viewDidLoad { NSLog(@"test array: %@", aXMLParser.array); NSLog(@"test dict: %@", aXMLParser.dictionary); NSLog(@"test element: %@", aXMLParser.element); } When I test the value of my array, a dict or an element in the XMLParser.h file I get my result. What am I doing wrong so I can't call my results in my controller file? Any help is welcome, because I'm pretty stuck right now :/

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  • Difference between these two ways of localizing a string in an aspx/ascx file?

    - by Brandon
    When I started localizing a website the first time, I just did the localization like this: <%= Resources.ResourceFile.ResourceName %> and it seems to work perfectly fine. However, the ReSharper 5.0 Beta does it like this: <asp:Localize Text="<%$ Resources: ResourceFile, ResourceName %>" runat="server"> Value </asp:Localize> Does it matter which way it gets done? If it doesn't matter, is there any way to make ReSharper do it the way I'm doing it? I kind of prefer it this way since it is less text in the aspx/ascx files.

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  • What is the difference between Inversion of Control and Dependency injection in C++?

    - by rlbond
    I've been reading recently about DI and IoC in C++. I am a little confused (even after reading related questions here on SO) and was hoping for some clarification. It seems to me that being familiar with the STL and Boost leads to use of dependency injection quite a bit. For example, let's say I made a function that found the mean of a range of numbers: template <typename Iter> double mean(Iter first, Iter last) { double sum = 0; size_t number = 0; while (first != last) { sum += *(first++); ++number; } return sum/number; }; Is this dependency injection? Inversion of control? Neither? Let's look at another example. We have a class: class Dice { public: typedef boost::mt19937 Engine; Dice(int num_dice, Engine& rng) : n_(num_dice), eng_(rng) {} int roll() { int sum = 0; for (int i = 0; i < num_dice; ++i) sum += boost::uniform_int<>(1,6)(eng_); return sum; } private: Engine& eng_; int n_; }; This seems like dependency injection. But is it inversion of control? Also, if I'm missing something, can someone help me out?

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  • algorithm - How to sort a 0/1 array with 2n/3 comparisons?

    - by Jackson Tale
    In Algorithm Design Manual, there is such an excise 4-26 Consider the problem of sorting a sequence of n 0’s and 1’s using comparisons. For each comparison of two values x and y, the algorithm learns which of x < y, x = y, or x y holds. (a) Give an algorithm to sort in n - 1 comparisons in the worst case. Show that your algorithm is optimal. (b) Give an algorithm to sort in 2n/3 comparisons in the average case (assuming each of the n inputs is 0 or 1 with equal probability). Show that your algorithm is optimal. For (a), I think it is fairly easy. I can choose a[n-1] as pivot, then do something like in quicksort partition, scan 0 to n - 2, find the middle point where left side is all 0 and right side is all 1, this take n - 1 comparisons. But for (b), I can't get a clue. It says "each of the n inputs is 0 or 1 with equal probability", so I guess I can assume the numbers of 0 and 1 equal? But how can I get a result which is related to 1/3? divide the whole array into 3 groups? Thanks

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  • In SQL / MySQL, what is the difference between "On" and "Where" in a join statement?

    - by Jian Lin
    The following statements give the same result (one is using "on", and the other using "where"): mysql> select * from gifts INNER JOIN sentGifts on gifts.giftID = sentGifts.giftID; mysql> select * from gifts INNER JOIN sentGifts where gifts.giftID = sentGifts.giftID; I can only see in a case of a Left Outer Join finding the "unmatched" cases: (to find out the gifts that were never sent by anybody) mysql> select name from gifts LEFT OUTER JOIN sentgifts on gifts.giftID = sentgifts.giftID where sentgifts.giftID IS NULL; In this case, it is first using "on", and then "where". Does the "on" first do the matching, and then "where" does the "secondary" filtering? Or is there a more general rule of using "on" versus "where"? Thanks.

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  • What are MVP and MVC and what is the difference?

    - by Wolfbyte
    When looking beyond the RAD (drag-drop and configure) way of building User Interfaces that many tools encourage you are likely to come across 2 design patterns called Model-View-Controller and Model-View-Presenter. My question has two parts to it: What issues do these patterns address? How are they similar? How are they different?

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  • On Solaris, what is the difference between cut and gcut?

    - by Chris J
    I recently came across this crazy script bug on one of my Solaris machines. I found that cut on Solaris skips lines from the files that it processes (or at least very large ones - 800 MB in my case). > cut -f 1 test.tsv | wc -l 457030 > gcut -f 1 test.tsv | wc -l 840571 > cut -f 1 test.tsv > temp_cut_1.txt > gcut -f 1 test.tsv > temp_gcut_1.txt > diff temp_cut_1.txt temp_gcut_1.txt | grep '[<]' | wc -l 0 My question is what the hell is going on with Solaris cut? My solution is updating my scripts to use gcut but... what the hell?

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