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  • A tiny Utility to recycle an IIS Application Pool

    - by Rick Strahl
    In the last few weeks I've annoyingly been having problems with an area on my Web site. It's basically ancient articles that are using ASP classic pages and for reasons unknown ASP classic locks up on these pages frequently. It's not an individual page, but ALL ASP classic pages lock up. Ah yes, gotta old tech gone bad. It's not super critical since the content is really old, but still a hassle since it's linked content that still gets quite a bit of traffic. When it happens all ASP classic in that AppPool dies. I've been having a hard time tracking this one down - I suspect an errant COM object I have a Web Monitor running on the server that's checking for failures and while the monitor can detect the failures when the timeouts occur, I didn't have a good way to just restart that particular application pool. I started putzing around with PowerShell, but - as so often seems the case - I can never get the PowerShell syntax right - I just don't use it enough and have to dig out cheat sheets etc. In any case, after about 20 minutes of that I decided to just create a small .NET Console Application that does the trick instead, and in a few minutes I had this:using System; using System.Collections.Generic; using System.Text; using System.DirectoryServices; namespace RecycleApplicationPool { class Program { static void Main(string[] args) { string appPoolName = "DefaultAppPool"; string machineName = "LOCALHOST"; if (args.Length > 0) appPoolName = args[0]; if (args.Length > 1) machineName = args[1]; string error = null; DirectoryEntry root = null; try { Console.WriteLine("Restarting Application Pool " + appPoolName + " on " + machineName + "..."); root = new DirectoryEntry("IIS://" + machineName + "/W3SVC/AppPools/" +appPoolName); Console.WriteLine(root.InvokeGet("Name")); root.Invoke("Recycle"); Console.WriteLine("Application Pool recycling complete..."); } catch(Exception ex) { error = "Error: Unable to access AppPool: " + ex.Message; } if ( !string.IsNullOrEmpty(error) ) { Console.WriteLine(error); return; } } } } To run in you basically provide the name of the ApplicationPool and optionally a machine name if it's not on the local box. RecyleApplicationPool.exe "WestWindArticles" And off it goes. What's nice about AppPool recycling versus doing a full IISRESET is that it only affects the AppPool, and more importantly AppPool recycles happen in a staggered fashion - the existing instance isn't shut down immediately until requests finish while a new instance is fired up to handle new requests. So, now I can easily plug this Executable into my West Wind Web Monitor as an action to take when the site is not responding or timing out which is a big improvement than hanging for an unspecified amount of time. I'm posting this fairly trivial bit of code just in case somebody (maybe myself a few months down the road) is searching for ApplicationPool recyling code. It's clearly trivial, but I've written batch files for this a bunch of times before and actually having a small utility around without having to worry whether Powershell is installed and configured right is actually an improvement. Next time I think about using PowerShell remind me that it's just easier to just build a small .NET Console app, 'k? :-) Resources Download Executable and VS Project© Rick Strahl, West Wind Technologies, 2005-2012Posted in IIS7  .NET  Windows   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • Too complex/too many objects?

    - by Mike Fairhurst
    I know that this will be a difficult question to answer without context, but hopefully there are at least some good guidelines to share on this. The questions are at the bottom if you want to skip the details. Most are about OOP in general. Begin context. I am a jr dev on a PHP application, and in general the devs I work with consider themselves to use many more OO concepts than most PHP devs. Still, in my research on clean code I have read about so many ways of using OO features to make code flexible, powerful, expressive, testable, etc. that is just plain not in use here. The current strongly OO API that I've proposed is being called too complex, even though it is trivial to implement. The problem I'm solving is that our permission checks are done via a message object (my API, they wanted to use arrays of constants) and the message object does not hold the validation object accountable for checking all provided data. Metaphorically, if your perm containing 'allowable' and 'rare but disallowed' is sent into a validator, the validator may not know to look for 'rare but disallowed', but approve 'allowable', which will actually approve the whole perm check. We have like 11 validators, too many to easily track at such minute detail. So I proposed an AtomicPermission class. To fix the previous example, the perm would instead contain two atomic permissions, one wrapping 'allowable' and the other wrapping 'rare but disallowed'. Where previously the validator would say 'the check is OK because it contains allowable,' now it would instead say '"allowable" is ok', at which point the check ends...and the check fails, because 'rare but disallowed' was not specifically okay-ed. The implementation is just 4 trivial objects, and rewriting a 10 line function into a 15 line function. abstract class PermissionAtom { public function allow(); // maybe deny() as well public function wasAllowed(); } class PermissionField extends PermissionAtom { public function getName(); public function getValue(); } class PermissionIdentifier extends PermissionAtom { public function getIdentifier(); } class PermissionAction extends PermissionAtom { public function getType(); } They say that this is 'not going to get us anything important' and it is 'too complex' and 'will be difficult for new developers to pick up.' I respectfully disagree, and there I end my context to begin the broader questions. So the question is about my OOP, are there any guidelines I should know: is this too complicated/too much OOP? Not that I expect to get more than 'it depends, I'd have to see if...' when is OO abstraction too much? when is OO abstraction too little? how can I determine when I am overthinking a problem vs fixing one? how can I determine when I am adding bad code to a bad project? how can I pitch these APIs? I feel the other devs would just rather say 'its too complicated' than ask 'can you explain it?' whenever I suggest a new class.

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  • What are the reasons to use dos batch programs in Windows?

    - by DVK
    Question What would be a good (ideally, technical) reason to ever program some non-trivial task in dos batch language on a modern Windows system as opposed to downloading either PowerShell, or ActiveState Perl? To be more specific, I make the following two assumptions for the duration of this question: anyone technical enough to be able to write a medium-complexity batch script is technical enough to install either of the scripting interpreters. Neither of those two present enough of a learning curve for basic batch replacement tasks that said curve would outweigh the pain of doing any remotely-non-trivial task in batch. Notes "You need a batch program for autoexec.bat" is not a valid reason. Your autoexec.bat may consist of simply calling non-batch script. If you disagree with either of my 2 assumptions above, that's fine, and I may be wrong. But my question is specifically "assuming those 2 assumptions are correct, what would be the reason to still stick with batch?" If it makes it easier to suspend disbelief (in case you disagree with me), add in a 3rd assumption that the question is limited to people who already posess at least some modicum of PowerShell or Perl experience. To re-iterate - this is not meant to be a subjective question about how easy it is to learn PSh or ASPerl compared to doing advanced batch coding. That is a separate question that is too subjective to be bothered with in this post. Background: I used to do some fairly complicated batch programming back in the elder days, and remember batch as one of the worst possble programming languages I had encountered. The idea for this question came after seeing a bunch of batch questions on SO, and trying to grok the answer of one of them out of sheer curiosity and giving up in pain after a minute, exclaiming mentally "why would anyone go through this pain instead of doing that in 1 line of Perl?" :) My own plausible answer I assume there may be an an likely DOS-compatible system, which has DOS interpreter but has no compatible PowerShell or Perl... I'm not aware of one but not completely impossible.

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  • Is there a standard mapping between JSON and Protocol Buffers?

    - by Daniel Earwicker
    From a comment on the announcement blog post: Regarding JSON: JSON is structured similarly to Protocol Buffers, but protocol buffer binary format is still smaller and faster to encode. JSON makes a great text encoding for protocol buffers, though -- it's trivial to write an encoder/decoder that converts arbitrary protocol messages to and from JSON, using protobuf reflection. This is a good way to communicate with AJAX apps, since making the user download a full protobuf decoder when they visit your page might be too much. It may be trivial to cook up a mapping, but is there a single "obvious" mapping between the two that any two separate dev teams would naturally settle on? If two products supported PB data and could interoperate because they shared the same .proto spec, I wonder if they would still be able to interoperate if they independently introduced a JSON reflection of the same spec. There might be some arbitrary decisions to be made, e.g. should enum values be represented by a string (to be human-readable a la typical JSON) or by their integer value? So is there an established mapping, and any open source implementations for generating JSON encoder/decoders from .proto specs?

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  • Grails Deployment - Fastest way to get deployed?

    - by gav
    Hi All, If anyone has or is running a Grails application on their server I would appreciate some details on where to go after creating the WAR. Background I chose grails because with Google App Engine and the App Engine Plugin deployment should have been trivial. This issue is that there is a bug which makes any application pretty much unusable, I wish this had been more prominent so I didn't have to get to the point of seeing the error myself before I was aware of it. The next option was EC2 and the Cloud Tools plugin, it seems Cloud Tools worked with grails 1.0 but doesn't work with the current 1.2.1 due to issues getting the JAR dependencies. It also seems that Cloud Tools has been succeeded by Cloud Foundry which is in beta, will cost extra money and has limited places (I signed up but haven't got an e-mail). Question My application is painfully trivial, it has a small load, small data requirements and doesn't need to scale past 5 users. How can I deploy my grails app as quickly and painlessly as possible? Specifically: Are there any hosting companies that have tomcat installed on their servers out of the box that I can sign up to and use that will just work? Do you know of any simple tutorials for getting a grails application deployed to EC2 without Cloud Tools? Thanks in advance, Gav Side-note: I picked grails because of good advice from SO, it should have been a very short time from development to deployed product except the tools for auto-deployment aren't that mature and I've never configured a server before.

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  • C++ Exception Handling

    - by user1413793
    So I was writing some code and I noticed that apart from syntactical, type, and other compile-time errors, C++ does not throw any other exceptions. So I decided to test this out with a very trivial program: #include<iostream> int main() { std::count<<5/0<<std::endl; return 1 } When I compiled it using g++, g++ gave me a warning saying I was dividing by 0. But it still compiled the code. Then when I ran it, it printed some really large arbitrary number. When I want to know is, how does C++ deal with exceptions? Integer division by 0 should be a very trivial example of when an exception should be thrown and the program should terminate. Do I have to essentially enclose my entire program in a huge try block and then catch certain exceptions? I know in Python when an exception is thrown, the program will immediately terminate and print out the error. What does C++ do? Are there even runtime exceptions which stop execution and kill the program?

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  • Loading an XML configuration file BEFORE the flex application loads

    - by Shahar
    Hi, We are using an XML file as an external configuration file for several parameters in our application (including default values for UI components and properties values of some service layer objects). The idea is to be able to load the XML configuration file before the flex application initializes any of its components. This is crucial because XML loading is processed a-synchronously in flex, which can potentially cause race-conditions in the application. For example: the configuration file holds the endpoint URL of a web service used to obtain data from the server. The URL resides in the XML because we want to allow our users to alter the endpoint URL according to their environment. Now because the endpoint URL is retrieved only after the XML has been completely loaded, some of the application's components might be invoking operations on this web service before it is initialized with the correct endpoint. The trivial solution would have been to suspend the initialization of the application until the complete event is dispatched by the loader. But it appears that this solution is far from being trivial. I haven't found a single solution that allows me to load the XML before any other object in the application. Can anyone advice or comment on this matter? Regards, Shahar

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  • Treating differential operator as algebraic entity

    - by chappar
    I know that this question is offtopic and don't belong here. But i didn't know somewhere else to ask. So here is the question. I was reading e:the story of a number by Eli Maor, where he treats differential operator as just like any algebraic entity. For example if we have a differential equation like y’’ + 5y’ - 6y = 0. This can be treaed as (D^2 + 5D – 6)y = 0. So, either y = 0 (trivial solution) or (D^2 + 5D – 6) = 0. Factoring out above equation we get (D-1)(D+6)= 0 with solutions as D = 1 and D = -6. Since D does not have any meaning on its own, multiplying by y on both the sides we get Dy = y and Dy = -6y for which the solutions are Ae^x and Be^-6x. Combining these 2 solutions we get Ae^x + Be^-6x. Now my doubt is this approach break when we have an equation like D^2y = 0. Which means y = 0 (again trivial) or D^2 = 0 which means D = 0. Now Dy = y*0 = 0. That means y = C ( a constant). The actual answer should be Cx. I know that it is stupidity to treat D^2 = 0 as D = 0, it led me to doubt the entire process of treating differential equation as algebraic equation. Can someone throw light on this? Or any other site where i might get answer?

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  • is it possible to write a program which prints its own source code utilizing a "sequence-generating-

    - by guest
    is it possible to write a program which prints its own source code utilizing a "sequence-generating-function"? what i call a sequence-generating-function is simply a function which returns a value out of a specific interval (i.e. printable ascii-charecters (32-126)). the point now is, that this generated sequence should be the programs own source-code. as you see, implementing a function which returns an arbitrary sequence is really trivial, but since the returned sequence must contain the implementation of the function itself it is a highly non-trivial task. this is how such a program (and its corresponding output) could look like #include <stdio.h> int fun(int x) { ins1; ins2; ins3; . . . return y; } int main(void) { int i; for ( i=0; i<size of the program; i++ ) { printf("%c", fun(i)); } return 0; } i personally think it is not possible, but since i don't know very much about the underlying matter i posted my thoughts here. i'm really looking forward to hear some opinions!

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  • Link compatibility between C++ and D

    - by Caspin
    D easily interfaces with C. D just as easily interfaces with C++, but (and it's a big but) the C++ needs to be extremely trivial. The code cannot use: namespaces templates multiple inheritance mix virtual with non-virtual methods more? I completely understand the inheritance restriction. The rest however, feel like artificial limitations. Now I don't want to be able to use std::vector<T> directly, but I would really like to be able to link with std::vector<int> as an externed template. The C++ interfacing page has this particularly depressing comment. D templates have little in common with C++ templates, and it is very unlikely that any sort of reasonable method could be found to express C++ templates in a link-compatible way with D. This means that the C++ STL, and C++ Boost, likely will never be accessible from D. Admittedly I'll probably never need std::vector while coding in D, but I'd love to use QT or boost. So what's the deal. Why is it so hard to express non-trivial C++ classes in D? Would it not be worth it to add some special annotations or something to express at least namespaces?

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  • Where to place interactive objects in JavaScript?

    - by Chris
    I'm creating a web based application (i.e. JavaScript with jQuery and lots of SVG) where the user interacts with "objects" on the screen (think of DIVs that can be draged around, resized and connected by arraows - like a vector drawing programm or a graphical programming language). As each "object" contains individual information but is allways belonging to a "class" of elements it's obvious that this application should be programmed by using an OOP approach. But where do I store the "objects" best? Should I create a global structure ("registry") with all (JS native) objects and tell them "draw yourself on the DOM"? Or should I avoid such a structure and think of the (relevant) DOM nodes as my objects and attach the relevant data as .data() to them? The first approach is very MVC - but I guess the attachment of all the event handlers will be non trivial. The second approach will handle the events in a trivial way and it doesn't create a duplicate structure, but I guess the usual OO stuff (like methods) will be more complex. What do you recomend? I think the answer will be JavaScript and SVG specific as "usual" programming languages don't have such a highly organized output "canvas".

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  • Best practices to deal with "slightly different" branches of source code

    - by jedi_coder
    This question is rather agnostic than related to a certain version control program. Assume there is a source code tree under certain distributed version control. Let's call it A. At some point somebody else clones it and gets its own copy. Let's call it B. I'll call A and B branches, even if some version control tools have different definitions for branches (some might call A and B repositories). Let's assume that branch A is the "main" branch. In the context of distributed version control this only means that branch A is modified much more actively and the owner of branch B periodically syncs (pulls) new updates from branch A. Let's consider that a certain source file in branch B contains a class (again, it's also language agnostic). The owner of branch B considers that some class methods are more appropriate and groups them together by moving them inside the class body. Functionally nothing has changed - this is a very trivial refactoring of the code. But the change gets reflected in diffs. Now, assuming that this change from branch B will never get merged into branch A, the owner of branch B will always get this difference when pulling from branch A and merging into his own workspace. Even if there's only one such trivial change, the owner of branch B needs to resolve conflicts every time when pulling from branch A. As long as branches A and B are modified independently, more and more conflicts like this appear. What is the workaround for this situation? Which workflow should the owner of branch B follow to minimize the effort for periodically syncing with branch A?

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  • C#/.NET Little Wonders: The Joy of Anonymous Types

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the .NET 3 Framework, Microsoft introduced the concept of anonymous types, which provide a way to create a quick, compiler-generated types at the point of instantiation.  These may seem trivial, but are very handy for concisely creating lightweight, strongly-typed objects containing only read-only properties that can be used within a given scope. Creating an Anonymous Type In short, an anonymous type is a reference type that derives directly from object and is defined by its set of properties base on their names, number, types, and order given at initialization.  In addition to just holding these properties, it is also given appropriate overridden implementations for Equals() and GetHashCode() that take into account all of the properties to correctly perform property comparisons and hashing.  Also overridden is an implementation of ToString() which makes it easy to display the contents of an anonymous type instance in a fairly concise manner. To construct an anonymous type instance, you use basically the same initialization syntax as with a regular type.  So, for example, if we wanted to create an anonymous type to represent a particular point, we could do this: 1: var point = new { X = 13, Y = 7 }; Note the similarity between anonymous type initialization and regular initialization.  The main difference is that the compiler generates the type name and the properties (as readonly) based on the names and order provided, and inferring their types from the expressions they are assigned to. It is key to remember that all of those factors (number, names, types, order of properties) determine the anonymous type.  This is important, because while these two instances share the same anonymous type: 1: // same names, types, and order 2: var point1 = new { X = 13, Y = 7 }; 3: var point2 = new { X = 5, Y = 0 }; These similar ones do not: 1: var point3 = new { Y = 3, X = 5 }; // different order 2: var point4 = new { X = 3, Y = 5.0 }; // different type for Y 3: var point5 = new {MyX = 3, MyY = 5 }; // different names 4: var point6 = new { X = 1, Y = 2, Z = 3 }; // different count Limitations on Property Initialization Expressions The expression for a property in an anonymous type initialization cannot be null (though it can evaluate to null) or an anonymous function.  For example, the following are illegal: 1: // Null can't be used directly. Null reference of what type? 2: var cantUseNull = new { Value = null }; 3:  4: // Anonymous methods cannot be used. 5: var cantUseAnonymousFxn = new { Value = () => Console.WriteLine(“Can’t.”) }; Note that the restriction on null is just that you can’t use it directly as the expression, because otherwise how would it be able to determine the type?  You can, however, use it indirectly assigning a null expression such as a typed variable with the value null, or by casting null to a specific type: 1: string str = null; 2: var fineIndirectly = new { Value = str }; 3: var fineCast = new { Value = (string)null }; All of the examples above name the properties explicitly, but you can also implicitly name properties if they are being set from a property, field, or variable.  In these cases, when a field, property, or variable is used alone, and you don’t specify a property name assigned to it, the new property will have the same name.  For example: 1: int variable = 42; 2:  3: // creates two properties named varriable and Now 4: var implicitProperties = new { variable, DateTime.Now }; Is the same type as: 1: var explicitProperties = new { variable = variable, Now = DateTime.Now }; But this only works if you are using an existing field, variable, or property directly as the expression.  If you use a more complex expression then the name cannot be inferred: 1: // can't infer the name variable from variable * 2, must name explicitly 2: var wontWork = new { variable * 2, DateTime.Now }; In the example above, since we typed variable * 2, it is no longer just a variable and thus we would have to assign the property a name explicitly. ToString() on Anonymous Types One of the more trivial overrides that an anonymous type provides you is a ToString() method that prints the value of the anonymous type instance in much the same format as it was initialized (except actual values instead of expressions as appropriate of course). For example, if you had: 1: var point = new { X = 13, Y = 42 }; And then print it out: 1: Console.WriteLine(point.ToString()); You will get: 1: { X = 13, Y = 42 } While this isn’t necessarily the most stunning feature of anonymous types, it can be handy for debugging or logging values in a fairly easy to read format. Comparing Anonymous Type Instances Because anonymous types automatically create appropriate overrides of Equals() and GetHashCode() based on the underlying properties, we can reliably compare two instances or get hash codes.  For example, if we had the following 3 points: 1: var point1 = new { X = 1, Y = 2 }; 2: var point2 = new { X = 1, Y = 2 }; 3: var point3 = new { Y = 2, X = 1 }; If we compare point1 and point2 we’ll see that Equals() returns true because they overridden version of Equals() sees that the types are the same (same number, names, types, and order of properties) and that the values are the same.   In addition, because all equal objects should have the same hash code, we’ll see that the hash codes evaluate to the same as well: 1: // true, same type, same values 2: Console.WriteLine(point1.Equals(point2)); 3:  4: // true, equal anonymous type instances always have same hash code 5: Console.WriteLine(point1.GetHashCode() == point2.GetHashCode()); However, if we compare point2 and point3 we get false.  Even though the names, types, and values of the properties are the same, the order is not, thus they are two different types and cannot be compared (and thus return false).  And, since they are not equal objects (even though they have the same value) there is a good chance their hash codes are different as well (though not guaranteed): 1: // false, different types 2: Console.WriteLine(point2.Equals(point3)); 3:  4: // quite possibly false (was false on my machine) 5: Console.WriteLine(point2.GetHashCode() == point3.GetHashCode()); Using Anonymous Types Now that we’ve created instances of anonymous types, let’s actually use them.  The property names (whether implicit or explicit) are used to access the individual properties of the anonymous type.  The main thing, once again, to keep in mind is that the properties are readonly, so you cannot assign the properties a new value (note: this does not mean that instances referred to by a property are immutable – for more information check out C#/.NET Fundamentals: Returning Data Immutably in a Mutable World). Thus, if we have the following anonymous type instance: 1: var point = new { X = 13, Y = 42 }; We can get the properties as you’d expect: 1: Console.WriteLine(“The point is: ({0},{1})”, point.X, point.Y); But we cannot alter the property values: 1: // compiler error, properties are readonly 2: point.X = 99; Further, since the anonymous type name is only known by the compiler, there is no easy way to pass anonymous type instances outside of a given scope.  The only real choices are to pass them as object or dynamic.  But really that is not the intention of using anonymous types.  If you find yourself needing to pass an anonymous type outside of a given scope, you should really consider making a POCO (Plain Old CLR Type – i.e. a class that contains just properties to hold data with little/no business logic) instead. Given that, why use them at all?  Couldn’t you always just create a POCO to represent every anonymous type you needed?  Sure you could, but then you might litter your solution with many small POCO classes that have very localized uses. It turns out this is the key to when to use anonymous types to your advantage: when you just need a lightweight type in a local context to store intermediate results, consider an anonymous type – but when that result is more long-lived and used outside of the current scope, consider a POCO instead. So what do we mean by intermediate results in a local context?  Well, a classic example would be filtering down results from a LINQ expression.  For example, let’s say we had a List<Transaction>, where Transaction is defined something like: 1: public class Transaction 2: { 3: public string UserId { get; set; } 4: public DateTime At { get; set; } 5: public decimal Amount { get; set; } 6: // … 7: } And let’s say we had this data in our List<Transaction>: 1: var transactions = new List<Transaction> 2: { 3: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = 2200.00m }, 4: new Transaction { UserId = "Jim", At = DateTime.Now, Amount = -1100.00m }, 5: new Transaction { UserId = "Jim", At = DateTime.Now.AddDays(-1), Amount = 900.00m }, 6: new Transaction { UserId = "John", At = DateTime.Now.AddDays(-2), Amount = 300.00m }, 7: new Transaction { UserId = "John", At = DateTime.Now, Amount = -10.00m }, 8: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = 200.00m }, 9: new Transaction { UserId = "Jane", At = DateTime.Now, Amount = -50.00m }, 10: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = -100.00m }, 11: new Transaction { UserId = "Jaime", At = DateTime.Now.AddDays(-3), Amount = 300.00m }, 12: }; So let’s say we wanted to get the transactions for each day for each user.  That is, for each day we’d want to see the transactions each user performed.  We could do this very simply with a nice LINQ expression, without the need of creating any POCOs: 1: // group the transactions based on an anonymous type with properties UserId and Date: 2: byUserAndDay = transactions 3: .GroupBy(tx => new { tx.UserId, tx.At.Date }) 4: .OrderBy(grp => grp.Key.Date) 5: .ThenBy(grp => grp.Key.UserId); Now, those of you who have attempted to use custom classes as a grouping type before (such as GroupBy(), Distinct(), etc.) may have discovered the hard way that LINQ gets a lot of its speed by utilizing not on Equals(), but also GetHashCode() on the type you are grouping by.  Thus, when you use custom types for these purposes, you generally end up having to write custom Equals() and GetHashCode() implementations or you won’t get the results you were expecting (the default implementations of Equals() and GetHashCode() are reference equality and reference identity based respectively). As we said before, it turns out that anonymous types already do these critical overrides for you.  This makes them even more convenient to use!  Instead of creating a small POCO to handle this grouping, and then having to implement a custom Equals() and GetHashCode() every time, we can just take advantage of the fact that anonymous types automatically override these methods with appropriate implementations that take into account the values of all of the properties. Now, we can look at our results: 1: foreach (var group in byUserAndDay) 2: { 3: // the group’s Key is an instance of our anonymous type 4: Console.WriteLine("{0} on {1:MM/dd/yyyy} did:", group.Key.UserId, group.Key.Date); 5:  6: // each grouping contains a sequence of the items. 7: foreach (var tx in group) 8: { 9: Console.WriteLine("\t{0}", tx.Amount); 10: } 11: } And see: 1: Jaime on 06/18/2012 did: 2: -100.00 3: 300.00 4:  5: John on 06/19/2012 did: 6: 300.00 7:  8: Jim on 06/20/2012 did: 9: 900.00 10:  11: Jane on 06/21/2012 did: 12: 200.00 13: -50.00 14:  15: Jim on 06/21/2012 did: 16: 2200.00 17: -1100.00 18:  19: John on 06/21/2012 did: 20: -10.00 Again, sure we could have just built a POCO to do this, given it an appropriate Equals() and GetHashCode() method, but that would have bloated our code with so many extra lines and been more difficult to maintain if the properties change.  Summary Anonymous types are one of those Little Wonders of the .NET language that are perfect at exactly that time when you need a temporary type to hold a set of properties together for an intermediate result.  While they are not very useful beyond the scope in which they are defined, they are excellent in LINQ expressions as a way to create and us intermediary values for further expressions and analysis. Anonymous types are defined by the compiler based on the number, type, names, and order of properties created, and they automatically implement appropriate Equals() and GetHashCode() overrides (as well as ToString()) which makes them ideal for LINQ expressions where you need to create a set of properties to group, evaluate, etc. Technorati Tags: C#,CSharp,.NET,Little Wonders,Anonymous Types,LINQ

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  • Default Text Color in Apple Mail.app

    - by Axeva
    Is there any way to set the default font color for new messages in Mail.app? It's trivial to set the actual font, and text size. I cannot seem to get the application to change the text color though. It always defaults to black. After 5 or 6 major revisions of OS X, surely someone has thought of this, right?

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  • Does pointing *.[int].mydomain.com to 192.168.1.[int] constitute a security threat

    - by Dave
    For testing purposes, I've found it's really useful to point whatever.machineIP.mydomain.com to 192.168.1.machineIP : that way we can test each other's code without fidgetting with hosts files. I'm aware that this identifies our local IP addresses to the outside world, but if someone could access the network, it'd be trivial to sniff which of the local IP addresses respond to port 80 anyway. Is there anything I'm not seeing? Credit for the idea: http://news.ycombinator.com/item?id=1168896

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  • Static build ffmpeg 0.8

    - by Riduidel
    Is there anywhere an available static build of ffmpeg with all encoder/decoders libs for Linux (not a source tarball, but a binary) ? Although this question seems trivial, I spent the last half hour looking for it, without any success. EDIT I'm looking for binary to be run on x86 Suse 10 systems. Notice I can't use local package manager as all update repositories have bene removed by admin (to avoid uncontrolled software update).

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  • Dovecot, Postfix, Postfixadmin - can't send/receive mail

    - by Jack
    I am setting up a mail server: Dovecot and Postfix with MySQL support and Postfixadmin. Spend literally all day trying to figure it out, but I'm still unable to neither send nor receive any emails. To my knowledge, I have configured everything correctly, so either there is another problem, or my knowledge isn't good enough. Here is what I get when I use "echo test | mail [email protected]:" Jul 11 00:41:07 server postfix/pickup[17999]: 5B0D32AE1B: uid=0 from= Jul 11 00:41:07 server postfix/cleanup[19444]: 5B0D32AE1B: message-id=<[email protected] Jul 11 00:41:07 server postfix/qmgr[18513]: 5B0D32AE1B: from=, size=329, nrcpt=1 (queue active) Jul 11 00:41:12 server postfix/smtp[19448]: 5B0D32AE1B: to=, relay=none, delay=5.3, delays=0.1/0.01/5.2/0, dsn=4.4.3, status=deferred (Host or domain name not found. Name service error for name=dsa.com type=MX: Host not found, try again) *@mail.asd.com is changed for privacy reasons, same goes for [email protected]. *The bold text is where it, for some reason, prints out dsa.com - even though I haven't found it anywhere in the files which I've edited during the installation, nor my DNS is .com in the first place. Here is what I get when I try to send out an email from Postfix Admin interface: Jul 11 00:49:08 server postfix/smtpd[19479]: connect from localhost[127.0.0.1] Jul 11 00:49:08 server postfix/trivial-rewrite[19484]: warning: do not list domain asd.com in BOTH mydestination and virtual_mailbox_domains Jul 11 00:49:08 server postfix/smtpd[19479]: 4F7892AE1E: client=localhost[127.0.0.1] Jul 11 00:49:08 server postfix/cleanup[19487]: 4F7892AE1E: message-id=<[email protected] Jul 11 00:49:08 server postfix/qmgr[18513]: 4F7892AE1E: from=, size=317, nrcpt=1 (queue active) Jul 11 00:49:08 server postfix/smtpd[19479]: disconnect from localhost[127.0.0.1] Jul 11 00:49:10 server postfix/smtpd[19492]: connect from localhost[127.0.0.1] Jul 11 00:49:10 server postfix/trivial-rewrite[19484]: warning: do not list domain asd.com in BOTH mydestination and virtual_mailbox_domains Jul 11 00:49:10 server postfix/smtpd[19492]: 743AE2AE1F: client=localhost[127.0.0.1] Jul 11 00:49:10 server postfix/cleanup[19487]: 743AE2AE1F: message-id=<[email protected] Jul 11 00:49:10 server postfix/qmgr[18513]: 743AE2AE1F: from=, size=772, nrcpt=1 (queue active) Jul 11 00:49:10 server postfix/smtpd[19492]: disconnect from localhost[127.0.0.1] Jul 11 00:49:10 server amavis[13437]: (13437-11) Passed CLEAN, LOCAL [127.0.0.1] - , Message-ID: <[email protected], mail_id: 86+KQY93ANel, Hits: -0.002, size: 317, queued_as: 743AE2AE1F, 2145 ms Jul 11 00:49:10 server postfix/smtp[19489]: 4F7892AE1E: to=, relay=127.0.0.1[127.0.0.1]:10024, delay=2.3, delays=0.17/0.01/0/2.1, dsn=2.0.0, status=sent (250 2.0.0 from MTA([127.0.0.1]:10025): 250 2.0.0 Ok: queued as 743AE2AE1F) Jul 11 00:49:10 server postfix/qmgr[18513]: 4F7892AE1E: removed I really don't know what might be the problem... If you need to know something, feel free to ask and I'll clarify something.

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  • Turn on Laptop backlight without a keyboard shortcut

    - by user24963
    I recently installed the latest drivers and my screen backlight turned off. The problem is that my Fn-F7 key combination doesn't work, so I can't turn it back on. I can see my screen at night if I hold a source of light next to the screen. So I can still do some trivial things with my laptop. Is there a way to turn the backlight on without using Fn-F7 key combination, either via the command line, or some other way?

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  • HTC ActiveSync contacts sync problem

    - by Jonas Elfström
    I'm trying to sync my HTC Desire (HTC Sense, ActiveSync, Android 2.1) phone with an Exchange server over the internet. Everything seems to be working just fine except that contacts already in the phone does not sync to the Exchange server. If I add a contact in Exchange it appears in the phone and if I remove that contact in the phone it disappears in Exchange. Seems I'm missing something trivial here or is it just not possible?

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  • mysql master-slave setup with synchronous replication

    - by imaginative
    I have a very trivial mysql master-slave setup going on between two servers. The problem is, replication is asynchronous, and this can cause issues (even on a low latency link), if the master server was to crash after a COMMIT before the replication thread from the slave was able to fetch the last bin log. Is there anyway to force mysql to do synchronous commits so that data consistency is guaranteed in a mysql-slave relationship?

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  • What do .# file names mean in Linux?

    - by Martin Wiboe
    This is probably trivial, but I'm quite new to Linux and I was unable to find any info online. In a folder, I can execute the command find . -regex '.*py' and get the following result: ./.#netMHC3.2.py Is this a file in the current directory? What can I do to display its contents? Thank you

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  • Windows 7 DNS stuck at manual

    - by Populus
    I am using the google dns servers most of the time, but for one particular wifi connection it blocks that ip so I have to revert back to automatically choosing DNS... The problem now is everytime I connect to this network, I have to change it back to automatic DNS manually (ironically), it's stuck on using the google DNS by default... It's a trivial problem, but would be fab if someone can help me out here...

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  • Replace clock battery on Dell Inspiron 8200?

    - by jacobsee
    I have an old Dell Inspiron 8200 laptop. Still mostly works, but the clock battery has died so everytime I power it on I need to go into the BIOS and set the proper clock time. From what I've been able to tell, replacing this battery is non-trivial, but I haven't found a clear answer. How do I replace the clock battery? And how do I buy a replacement?

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  • Recommendations or advice for shared computer control

    - by Telemachus
    Basic scenario: we are a school (overwhelmingly Mac, some Windows machines via BootCamp), and we are considering using DeepFreeze to guard the state of our shared machines. We have roughly 250 machines that are either shared laptops (which move around quite a bit) or common desktops in public spaces. Obviously, we spend a lot of time maintaining the machines and trying to reverse the inevitable drift as people make changes to the computers. We would like to control the integrity of the build we initially put onto the machines without handcuffing users and especially without using Mac's Parental Control software. (We've had nothing but bad experiences with it.) We've been testing DeepFreeze, and so far it's very impressive. But I'm curious to hear if people who have used DeepFreeze or any similar software have any advice or tips. To get things started, I will post my own pros and cons. Pros: The state of the machine is frozen in our chosen state. All changes made to the machine after that disappear upon restart. (This frozen state really appears to cover everything. I have yet to do something to a test machine that isn't instantly healed.) Tons of trivial but time-consuming maintenance is gone in an instant. Also, lots of not-so-trivial breakage should be avoided. There are good options, however, that allow you to create storage spaces either globally or per user. (Otherwise, stored files disappear upon reboot. For some machines, this is a good option itself. Simply warn people: save externally or else; this machine is a kiosk, not your storage space.) Cons: Anytime we actually need to make a change (upgrade basic software, add a printer or an airport permanently, add new software), the process is a bit more complex. Reboot into a special mode (thaw state), make changes, reboot back into frozen mode. If (when?) we forget this, we will end up making changes that disappear after the next reboot. Users will forget to save files correctly (in the right place or externally), and we will have loud, unpleasant conversations explaining that we can't recover the document they worked on all afternoon yesterday. The machine rebooted. The file is gone. These are my initial thoughts, but I would love to hear from other people who have experience with DeepFreeze or any similar software. What should we be careful about? Do the pros outweigh the cons? What gains or problems am I not seeing? Thanks.

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