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• PHP Resize image down and crop using imagemagick

  - by mr12086

  I'm trying to downsize image uploaded by users at the time of upload. This is no problem but I want to get specific with sizes now. I'm looking for some advice on an algorithm im struggling to produce that will take any shape image - square or rectangle of any widths/heights and downsize it. This image needs to be downsized to a target box size (this changes but is stored in a variable).. So it needs to downsize the image so that both the width and height are larger than the width and height of the target maintaining aspect ratio. but only just.. The target size will be used to crop the image so there is no white space around the edges etc. I'm looking for just the algorithm behind creating the correct resize based on different dimension images - I can handle the cropping, even resizing in most cases but it fails in a few so i'm reaching out. I'm not really asking for PHP code more pseudo. Either is fine obviously. Thanks Kindly.

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• How to efficiently convert String, integer, double, datetime to binary and vica versa?

  - by Ben

  Hi, I'm quite new to C# (I'm using .NET 4.0) so please bear with me. I need to save some object properties (their properties are int, double, String, boolean, datetime) to a file. But I want to encrypt the files using my own encryption, so I can't use FileStream to convert to binary. Also I don't want to use object serialization, because of performance issues. The idea is simple, first I need to somehow convert objects (their properties) to binary (array), then encrypt (some sort of xor) the array and append it to the end of the file. When reading first decrypt the array and then somehow convert the binary array back to object properties (from which I'll generate objects). I know (roughly =) ) how to convert these things by hand and I could code it, but it would be useless (too slow). I think the best way would be just to get properties' representation in memory and save that. But I don't know how to do it using C# (maybe using pointers?). Also I though about using MemoryStream but again I think it would be inefficient. I am thinking about class Converter, but it does not support toByte(datetime) (documentation says it always throws exception). For converting back I think the only options is class Converter. Note: I know the structure of objects and they will not change, also the maximum String length is also known. Thank you for all your ideas and time. EDIT: I will be storing only parts of objects, in some cases also parts of different objects (a couple of properties from one object type and a couple from another), thus I think that serialization is not an option for me.

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• Failure remediation strategy for File I/O

  - by Brett

  I'm doing buffered IO into a file, both read and write. I'm using fopen(), fseeko(), standard ANSI C file I/O functions. In all cases, I'm writing to a standard local file on a disk. How often do these file I/O operations fail, and what should the strategy be for failures? I'm not exactly looking for stats, but I'm looking for a general purpose statement on how far I should go to handle error conditions. For instance, I think everyone recognizes that malloc() could and probably will fail someday on some user's machine and the developer should check for a NULL being returned, but there is no great remediation strategy since it probably means the system is out of memory. At least, this seems to be the approach taken with malloc() on desktop systems, embedded systems are different. Likewise, is it worth reattempting a file I/O operation, or should I just consider a failure to be basically unrecoverable, etc. I would appreciate some code samples demonstrating proper usage, or a library guide reference that indicates how this is to be handled. Any other data is, of course, welcome.

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• How to generate a number in arbitrary range using random()={0..1} preserving uniformness and density?

  - by psihodelia

  Generate a random number in range [x..y] where x and y are any arbitrary floating point numbers. Use function random(), which returns a random floating point number in range [0..1] from P uniformly distributed numbers (call it "density"). Uniform distribution must be preserved and P must be scaled as well. I think, there is no easy solution for such problem. To simplify it a bit, I ask you how to generate a number in interval [-0.5 .. 0.5], then in [0 .. 2], then in [-2 .. 0], preserving uniformness and density? Thus, for [0 .. 2] it must generate a random number from P*2 uniformly distributed numbers. The obvious simple solution random() * (x - y) + y will generate not all possible numbers because of the lower density for all abs(x-y)>1.0 cases. Many possible values will be missed. Remember, that random() returns only a number from P possible numbers. Then, if you multiply such number by Q, it will give you only one of P possible values, scaled by Q, but you have to scale density P by Q as well.

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• Alternatives to LINQ To SQL on high loaded pages

  - by Alex

  To begin with, I LOVE LINQ TO SQL. It's so much easier to use than direct querying. But, there's one great problem: it doesn't work well on high loaded requests. I have some actions in my ASP.NET MVC project, that are called hundreds times every minute. I used to have LINQ to SQL there, but since the amount of requests is gigantic, LINQ TO SQL almost always returned "Row not found or changed" or "X of X updates failed". And it's understandable. For instance, I have to increase some value by one with every request. var stat = DB.Stats.First(); stat.Visits++; // .... DB.SubmitChanges(); But while ASP.NET was working on those //... instructions, the stats.Visits value stored in the table got changed. I found a solution, I created a stored procedure UPDATE Stats SET Visits=Visits+1 It works well. Unfortunately now I'm getting more and more moments like that. And it sucks to create stored procedures for all cases. So my question is, how to solve this problem? Are there any alternatives that can work here? I hear that Stackoverflow works with LINQ to SQL. And it's more loaded than my site.

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• php function to make slug (url string)

  - by andufo

  function gen_slug($str){ # special accents $a = array('À','Á','Â','Ã','Ä','Å','Æ','Ç','È','É','Ê','Ë','Ì','Í','Î','Ï','Ð','Ñ','Ò','Ó','Ô','Õ','Ö','Ø','Ù','Ú','Û','Ü','Ý','ß','à','á','â','ã','ä','å','æ','ç','è','é','ê','ë','ì','í','î','ï','ñ','ò','ó','ô','õ','ö','ø','ù','ú','û','ü','ý','ÿ','A','a','A','a','A','a','C','c','C','c','C','c','C','c','D','d','Ð','d','E','e','E','e','E','e','E','e','E','e','G','g','G','g','G','g','G','g','H','h','H','h','I','i','I','i','I','i','I','i','I','i','?','?','J','j','K','k','L','l','L','l','L','l','?','?','L','l','N','n','N','n','N','n','?','O','o','O','o','O','o','Œ','œ','R','r','R','r','R','r','S','s','S','s','S','s','Š','š','T','t','T','t','T','t','U','u','U','u','U','u','U','u','U','u','U','u','W','w','Y','y','Ÿ','Z','z','Z','z','Ž','ž','?','ƒ','O','o','U','u','A','a','I','i','O','o','U','u','U','u','U','u','U','u','U','u','?','?','?','?','?','?'); $b = array('A','A','A','A','A','A','AE','C','E','E','E','E','I','I','I','I','D','N','O','O','O','O','O','O','U','U','U','U','Y','s','a','a','a','a','a','a','ae','c','e','e','e','e','i','i','i','i','n','o','o','o','o','o','o','u','u','u','u','y','y','A','a','A','a','A','a','C','c','C','c','C','c','C','c','D','d','D','d','E','e','E','e','E','e','E','e','E','e','G','g','G','g','G','g','G','g','H','h','H','h','I','i','I','i','I','i','I','i','I','i','IJ','ij','J','j','K','k','L','l','L','l','L','l','L','l','l','l','N','n','N','n','N','n','n','O','o','O','o','O','o','OE','oe','R','r','R','r','R','r','S','s','S','s','S','s','S','s','T','t','T','t','T','t','U','u','U','u','U','u','U','u','U','u','U','u','W','w','Y','y','Y','Z','z','Z','z','Z','z','s','f','O','o','U','u','A','a','I','i','O','o','U','u','U','u','U','u','U','u','U','u','A','a','AE','ae','O','o'); return strtolower(preg_replace(array('/[^a-zA-Z0-9 -]/','/[ -]+/','/^-|-$/'),array('','-',''),str_replace($a,$b,$str))); } Works great, but i've found some cases in which it fails: echo gen_slug('andrés'); returns andras instead of andres why? any ideas on the preg_replace parameters?

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• Overlapping template partial specialization when wanting an "override" case: how to avoid the error?

  - by user173342

  I'm dealing with a pretty simple template struct that has an enum value set by whether its 2 template parameters are the same type or not. template<typename T, typename U> struct is_same { enum { value = 0 }; }; template<typename T> struct is_same<T, T> { enum { value = 1 }; }; This is part of a library (Eigen), so I can't alter this design without breaking it. When value == 0, a static assert aborts compilation. So I have a special numerical templated class SpecialCase that can do ops with different specializations of itself. So I set up an override like this: template<typename T> struct SpecialCase { ... }; template<typename LT, typename RT> struct is_same<SpecialCase<LT>, SpecialCase<RT>> { enum { value = 1 }; }; However, this throws the error: more than one partial specialization matches the template argument list Now, I understand why. It's the case where LT == RT, which steps on the toes of is_same<T, T>. What I don't know is how to keep my SpecialCase override and get rid of the error. Is there a trick to get around this? edit: To clarify, I need all cases where LT != RT to also be considered the same (have value 1). Not just LT == RT.

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• c++ Design pattern for CoW, inherited classes, and variable shared data?

  - by krunk

  I've designed a copy-on-write base class. The class holds the default set of data needed by all children in a shared data model/CoW model. The derived classes also have data that only pertains to them, but should be CoW between other instances of that derived class. I'm looking for a clean way to implement this. If I had a base class FooInterface with shared data FooDataPrivate and a derived object FooDerived. I could create a FooDerivedDataPrivate. The underlying data structure would not effect the exposed getters/setters API, so it's not about how a user interfaces with the objects. I'm just wondering if this is a typical MO for such cases or if there's a better/cleaner way? What peeks my interest, is I see the potential of inheritance between the the private data classes. E.g. FooDerivedDataPrivate : public FooDataPrivate, but I'm not seeing a way to take advantage of that polymorphism in my derived classes. class FooDataPrivate { public: Ref ref; // atomic reference counting object int a; int b; int c; }; class FooInterface { public: // constructors and such // .... // methods are implemented to be copy on write. void setA(int val); void setB(int val); void setC(int val); // copy constructors, destructors, etc. all CoW friendly private: FooDataPrivate *data; }; class FooDerived : public FooInterface { public: FooDerived() : FooInterface() {} private: // need more shared data for FooDerived // this is the ???, how is this best done cleanly? };

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• How can I make nested string splits?

  - by Statement

  I have what seemed at first to be a trivial problem but turned out to become something I can't figure out how to easily solve. I need to be able to store lists of items in a string. Then those items in turn can be a list, or some other value that may contain my separator character. I have two different methods that unpack the two different cases but I realized I need to encode the contained value from any separator characters used with string.Split. To illustrate the problem: string[] nested = { "mary;john;carl", "dog;cat;fish", "plainValue" } string list = string.Join(";", nested); string[] unnested = list.Split(';'); // EEK! returns 7 items, expected 3! This would produce a list "mary;john;carl;dog;cat;fish;plainValue", a value I can't split to get the three original nested strings from. Indeed, instead of the three original strings, I'd get 7 strings on split and this approach thus doesn't work at all. What I want is to allow the values in my string to be encoded so I can unpack/split the contents just the way before I packed/join them. I assume I might need to go away from string.Split and string.Join and that is perfectly fine. I might just have overlooked some useful class or method. How can I allow any string values to be packed / unpacked into lists? I prefer neat, simple solutions over bulky if possible. For the curious mind, I am making extensions for PlayerPrefs in Unity3D, and I can only work with ints, floats and strings. Thus I chose strings to be my data carrier. This is why I am making this nested list of strings.

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• C++ iterators, default initialization and what to use as an uninitialized sentinel.

  - by Hassan Syed

  The Context I have a custom template container class put together from a map and vector. The map resolves a string to an ordinal, and the vector resolves an ordinal (only an initial string to ordinal lookup is done, future references are to the vector) to the entry. The entries are modified intrusively to contain a a bool "assigned" and an iterator_type which is a const_iterator to the container class's map. My container class will use RCF's serialization code (which models boost::serialization) to serialize my container classes to nodes in a network. Serializing iterator's is not possible, or a can of worms, and I can easily regenerate them onces the vectors and maps are serialized on the remote site. The Question I need to default initialize, and be able to test that the iterator has not been assigned to (if it is assigned it is valid, if not it is invalid). Since map iterators are not invalidated upon operations performed on it (unless of course items are removed :D) am I to assume that map<x,y>::end() is a valid sentinel (regardless of the state of the map -- i.e., it could be empty) to initialize to ? I will always have access to the parent map, I'm just unsure wheather end() is the same as the map contents change. I don't want to use another level of indirection (--i.e., boost::optional) to achieve my goal, I'd rather forego compiler checks to correct logic, but it would be nice if I didn't need to. Misc This question exists, but most of its content seems non-sense. Assigning a NULL to an iterator is invalid according to g++ and clang++. This is another similar question, but it focuses on the common use-cases of iterators, which generally tends to be using the iterator to iterate, ofcourse in this use-case the state of the container isn't meant to change whilst iteration is going on.

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• C standard addressing simplification inconsistency

  - by Chris Lutz

  Section §6.5.3.2 "Address and indirection operators" ¶3 says (relevant section only): The unary & operator returns the address of its operand. ... If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted, except that the constraints on the operators still apply and the result is not an lvalue. Similarly, if the operand is the result of a [] operator, neither the & operator nor the unary * that is implied by the [] is evaluated and the result is as if the & operator were removed and the [] operator were changed to a + operator. ... This means that this: int *i = NULL; printf("%p", (void *) (&*i) ); printf("%p", (void *) (&i[10]) ); Should be perfectly legal, printing the null pointer (probably 0) and the null pointer plus 10 (probably 10). The standard seems very clear that both of those cases are required to be optimized. However, it doesn't seem to require the following to be optimized: struct { int a; short b; } *s = 0; printf("%p", (void *) (&s->b) ); This seems awfully inconsistent. I can see no reason that the above code shouldn't print the null pointer plus sizeof(int) (possibly 4). Simplifying a &-> expression is going to be the same conceptually (IMHO) as &[], a simple address-plus-offset. It's even an offset that's going to be determinable at compile time, rather than potentially runtime with the [] operator. Is there anything in the rationale about why this is so seemingly inconsistent?

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• How do I establish table association in JPA / Hibernate with existing database?

  - by Paperino

  Currently I have two tables in my database Encounters and Referrals: There is a one to many relationship between these two tables. Currently they are linked together with foreign keys. Right now I have public class Encounter extends JPASupport implements java.io.Serializable { @Column(name="referralid", unique=false, nullable=true, insertable=true, updatable=true) public Integer referralid; } But what I really want is public class Encounter extends JPASupport implements java.io.Serializable { .......... @OneToMany(cascade=CascadeType.PERSIST) public Set<Referrals> referral; ............ } So that I can eventually do a query like this: List<Encounter> cases = Encounter.find( "select distinct p from Encounter p join p.referrals as t where t.caseid =103" ).fetch(); How do I tell JPA that even though I have non-standard column names for my foreign keys and primary keys that its the object models that I want linked, not simply the integer value for the keys? Does this make sense? I hope so. Thanks in advanced!

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• Utility of List<T>.Sort() versus List<T>.OrderBy() for a member of a custom container class

  - by ccomet

  I've found myself running back through some old 3.5 framework legacy code, and found some points where there are a whole bunch of lists and dictionaries that must be updated in a synchronized fashion. I've determined that I can make this process infinitely easier to both utilize and understand by converging these into custom container classes of new custom classes. There are some points, however, where I came to concerns with organizing the contents of these new container classes by a specific inner property. For example, sorting by the ID number property of one class. As the container classes are primarily based around a generic List object, my first instinct was to write the inner classes with IComparable, and write the CompareTo method that compares the properties. This way, I can just call items.Sort() when I want to invoke the sorting. However, I've been thinking instead about using items = items.OrderBy(Func) instead. This way it is more flexible if I need to sort by any other property. Readability is better as well, since the property used for sorting will be listed in-line with the sort call rather than having to look up the IComparable code. The overall implementation feels cleaner as a result. I don't care for premature or micro optimization, but I like consistency. I find it best to stick with one kind of implementation for as many cases as it is appropriate, and use different implementations where it is necessary. Is it worth it to convert my code to use the LINQ OrderBy instead of using List.Sort? Is it a better practice to stick with the IComparable implementation for these custom containers? Are there any significant mechanical advantages offered by either path that I should be weighing the decision on? Or is their end-functionality equivalent to the point that it just becomes coder's preference?

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• Executing logic before save or validation with EF Code-First Models

  - by Ryan Norbauer

  I'm still getting accustomed to EF Code First, having spent years working with the Ruby ORM, ActiveRecord. ActiveRecord used to have all sorts of callbacks like before_validation and before_save, where it was possible to modify the object before it would be sent off to the data layer. I am wondering if there is an equivalent technique in EF Code First object modeling. I know how to set object members at the time of instantiation, of course, (to set default values and so forth) but sometimes you need to intervene at different moments in the object lifecycle. To use a slightly contrived example, say I have a join table linking Authors and Plays, represented with a corresponding Authoring object: public class Authoring { public int ID { get; set; } [Required] public int Position { get; set; } [Required] public virtual Play Play { get; set; } [Required] public virtual Author Author { get; set; } } where Position represents a zero-indexed ordering of the Authors associated to a given Play. (You might have a single "South Pacific" Play with two authors: a "Rodgers" author with a Position 0 and a "Hammerstein" author with a Position 1.) Let's say I wanted to create a method that, before saving away an Authoring record, it checked to see if there were any existing authors for the Play to which it was associated. If no, it set the Position to 0. If yes, it would find set the Position of the highest value associated with that Play and increment by one. Where would I implement such logic within an EF code first model layer? And, in other cases, what if I wanted to massage data in code before it is checked for validation errors? Basically, I'm looking for an equivalent to the Rails lifecycle hooks mentioned above, or some way to fake it at least. :)

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• pure/const functions in C++

  - by Albert

  Hi, I'm thinking of using pure/const functions more heavily in my C++ code. (pure/const attribute in GCC) However, I am curious how strict I should be about it and what could possibly break. The most obvious case are debug outputs (in whatever form, could be on cout, in some file or in some custom debug class). I probably will have a lot of functions, which don't have any side effects despite this sort of debug output. No matter if the debug output is made or not, this will absolutely have no effect on the rest of my application. Or another case I'm thinking of is the use of my own SmartPointer class. In debug mode, my SmartPointer class has some global register where it does some extra checks. If I use such an object in a pure/const function, it does have some slight side effects (in the sense that some memory probably will be different) which should not have any real side effects though (in the sense that the behaviour is in any way different). Similar also for mutexes and other stuff. I can think of many complex cases where it has some side effects (in the sense of that some memory will be different, maybe even some threads are created, some filesystem manipulation is made, etc) but has no computational difference (all those side effects could very well be left out and I would even prefer that). How does it work out in practice? If I mark such functions as pure/const, could it break anything (considering that the code is all correct)?

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• Given a main function and a cleanup function, how (canonically) do I return an exit status in Bash/Linux?

  - by Zac B

  Context: I have a bash script (a wrapper for other scripts, really), that does the following pseudocode: do a main function if the main function returns: $returncode = $? #most recent return code if the main function runs longer than a timeout: kill the main function $returncode = 140 #the semi-canonical "exceeded allowed wall clock time" status run a cleanup function if the cleanup function returns an error: #nonzero return code exit $? #exit the program with the status returned from the cleanup function else #cleanup was successful .... Question: What should happen after the last line? If the cleanup function was successful, but the main function was not, should my program return 0 (for the successful cleanup), or $returncode, which contains the (possibly nonzero and unsuccessful) return code of the main function? For a specific application, the answer would be easy: "it depends on what you need the script for." However, this is more of a general/canonical question (and if this is the wrong place for it, kill it with fire): in Bash (or Linux in general) programming, do you typically want to return the status that "means" something (i.e. $returncode) or do you ignore such subjectivities and simply return the code of the most recent function? This isn't Bash-specific: if I have a standalone executable of any kind, how, canonically should it behave in these cases? Obviously, this is somewhat debatable. Even if there is a system for these things, I'm sure that a lot of people ignore it. All the same, I'd like to know. Cheers!

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• If a nonblocking recv with MSG_PEEK succeeds, will a subsequent recv without MSG_PEEK also succeed?

  - by Michael Wolf

  Here's a simplified version of some code I'm working on: void stuff(int fd) { int ret1, ret2; char buffer[32]; ret1 = recv(fd, buffer, 32, MSG_PEEK | MSG_DONTWAIT); /* Error handling -- and EAGAIN handling -- would go here. Bail if necessary. Otherwise, keep going. */ /* Can this call to recv fail, setting errno to EAGAIN? */ ret2 = recv(fd, buffer, ret1, 0); } If we assume that the first call to recv succeeds, returning a value between 1 and 32, is it safe to assume that the second call will also succeed? Can ret2 ever be less than ret1? In which cases? (For clarity's sake, assume that there are no other error conditions during the second call to recv: that no signal is delivered, that it won't set ENOMEM, etc. Also assume that no other threads will look at fd. I'm on Linux, but MSG_DONTWAIT is, I believe, the only Linux-specific thing here. Assume that the right fnctl was set previously on other platforms.)

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• Multi threading in WCF RIA Services

  - by synergetic

  I use WCF RIA Services to update customer database. In domain service: public void UpdateCustomer(Customer customer) { this.ObjectContext.Customers.AttachAsModified(customer); syncCustomer(customer); } After update, a database trigger launches and depending on the columns updated it may insert a new record in CustomerChange table. syncCustomer(customer) method is executed to check for a new record in the CustomerChange table and if found it will create a text file which contains customer information and forwards that file to external system for import. Now this synchronization may take a time so I wanted to execute it in different thread. So: private void syncCustomer(Customer customer) { this.ObjectContext.SaveChanges(); new Thread(() => syncCustomerInfo(customer.CustomerID)) { IsBackground = true }.Start(); } private void syncCustomerInfo(int customerID) { //Thread.Sleep(2000); //does real job here ... ... } The problem is in most cases syncCustomerInfo method cannot find any new CustomerChange record even if it was definitely there. If I force thread sleep then it finds a new record. I also looked Entity Framework events but the only event provided by object context is SavingChanges which occur before changes are saved. Please suggest me what else to try.

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• how do use Ninject with class libraries I am developing?

  - by Greg

  Hi, If I am working on a class library how do I make use of Ninject here? Ie from the internal class library point of view and also from the client code? For example: should the class library have it's own IOC set up, or should it always assume the client code will supply? if no (ie it's upto the client to have the IOC in place) then where is the mapping data stored here'. Is this mapping of the class library's functionality to be places in the client? have a reusable library that is available, that uses interfaces with classes that use the getInstance concept to create concrete classes for you to use, then in this case would that make sense on the client side to use the IOC container to create instances of these classes? Or is that really applying a double layer of abstraction? Q2 Or in the cases where I'm building the reusable library myself and want the client to use an IOC container, then in my reusable library would I then dispense with any overhead of having factories or "getInstance" methods to instantiate the classes in the client? (i.e. as the IOC container would do this no?)

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• What's the best way to only output a tag if it exists in XSL?

  - by Morinar

  I'm working on an interface with a 3rd party app that basically needs to take XML that was spat out by the app and convert it into XML our system can deal with. It's basically just applying a stylesheet to the original XML to make it looks like "our" XML. I've noticed that in other stylesheets we have, there are constructs like this: <xsl:for-each select="State"> <StateAbbreviation> <xsl:value-of select="."/> </StateAbbreviation> </xsl:for-each> Basically, the "in" XML has a State tag that I need to output as our recognized StateAbbreviation tag. However, I want to ONLY output the StateAbbreviation tag if the "in" XML contains the State tag. The block above accomplishes this just fine, but is not very intuitive (at least it wasn't to me), as every time I see a for-each I assume there is more than one, whereas in these cases there is 0 or 1. My question: is that a standard-ish construct? If not, is there a more preferred way to do it? I could obviously check the string length (which is also being done in other stylesheets), but would like to do it the same, "best" way everywhere (assuming of course that a "best" way exists. Advice? Suggestions?

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• Disable validation in an object in Ruby on Rails

  - by J. Pablo Fernández

  I have an object which whether validation happens or not should depend on a boolean, or in another way, validation is optional. I haven't found a clean way to do it. What I'm currently doing is this (disclaimer: you cannot unsee, leave this page if you are too sensitive): def valid? if perform_validation super else super # Call valid? so that callbacks get called and things like encrypting passwords and generating salt in before_validation actually happen errors.clear # but then clear the errors true # and claim ourselves to be valid. This is super hacky! end end Any better ways? Before you point to the :if argument of many validations, this is for a user model which is using authlogic so it has a lot of validation rules. You can stop reading here if you belive me. If you don't, authlogic already sets some :ifs like: :if => :email_changed? which I have to turn into :if => Proc.new {|user| user.email_changed? and user.perform_validation} and in some other cases, since I'm also using authlogic-oid (OpenID) I just don't have control over the :if, authlogic-oid sets it in a way I cannot change it (in time) without further monkey patching. So I have to override seemingly unrelated functions, catch exceptions if a method doesn't exist, etc. The previous hacky solution if the best of my two attempts.

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• How to get a list of all Subversion commit author usernames?

  - by Quinn Taylor

  I'm looking for an efficient way to get the list of unique commit authors for an SVN repository as a whole, or for a given resource path. I haven't been able to find an SVN command specifically for this (and don't expect one) but I'm hoping there may be a better way that what I've tried so far in Terminal (on OS X): svn log --quiet | grep "^r" | awk '{print $3}' svn log --quiet --xml | grep author | sed -E "s:</?author>::g" Either of these will give me one author name per line, but they both require filtering out a fair amount of extra information. They also don't handle duplicates of the same author name, so for lots of commits by few authors, there's tons of redundancy flowing over the wire. More often than not I just want to see the unique author usernames. (It actually might be handy to infer the commit count for each author on occasion, but even in these cases it would be better if the aggregated data were sent across instead.) I'm generally working with client-only access, so svnadmin commands are less useful, but if necessary, I might be able to ask a special favor of the repository admin if strictly necessary or much more efficient. The repositories I'm working with have tens of thousands of commits and many active users, and I don't want to inconvenience anyone.

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• Does unboxing just return a pointer to the value within the boxed object on the heap?

  - by Charles

  I this MSDN Magazine article, the author states (emphasis mine): Note that boxing always creates a new object and copies the unboxed value's bits to the object. On the other hand, unboxing simply returns a pointer to the data within a boxed object: no memory copy occurs. However, it is commonly the case that your code will cause the data pointed to by the unboxed reference to be copied anyway. I'm confused by the sentence I've bolded and the sentence that follows it. From everything else I've read, including this MSDN page, I've never before heard that unboxing just returns a pointer to the value on the heap. I was under the impression that unboxing would result in you having a variable containing a copy of the value on the stack, just as you began with. After all, if my variable contains "a pointer to the value on the heap", then I haven't got a value type, I've got a pointer. Can someone explain what this means? Was the author on crack? (There is at least one other glaring error in the article). And if this is true, what are the cases where "your code will cause the data pointed to by the unboxed reference to be copied anyway"? I just noticed that the article is nearly 10 years old, so maybe this is something that changed very early on in the life of .Net.

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• Achieving Thread-Safety

  - by Smasher

  Question How can I make sure my application is thread-safe? Are their any common practices, testing methods, things to avoid, things to look for? Background I'm currently developing a server application that performs a number of background tasks in different threads and communicates with clients using Indy (using another bunch of automatically generated threads for the communication). Since the application should be highly availabe, a program crash is a very bad thing and I want to make sure that the application is thread-safe. No matter what, from time to time I discover a piece of code that throws an exception that never occured before and in most cases I realize that it is some kind of synchronization bug, where I forgot to synchronize my objects properly. Hence my question concerning best practices, testing of thread-safety and things like that. mghie: Thanks for the answer! I should perhaps be a little bit more precise. Just to be clear, I know about the principles of multithreading, I use synchronization (monitors) throughout my program and I know how to differentiate threading problems from other implementation problems. But nevertheless, I keep forgetting to add proper synchronization from time to time. Just to give an example, I used the RTL sort function in my code. Looked something like FKeyList.Sort (CompareKeysFunc); Turns out, that I had to synchronize FKeyList while sorting. It just don't came to my mind when initially writing that simple line of code. It's these thins I wanna talk about. What are the places where one easily forgets to add synchronization code? How do YOU make sure that you added sync code in all important places?

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• LINQ to Entities question about orderby and null collections.

  - by Chevex

  I am currently developing a forum. I am new to LINQ and EF. In my forum I have a display that shows a list of topics with the most recent topics first. The problem is that "most recent" is relative to the topic's replies. So I don't want to order the list by the topic's posted date, rather I want to order the list by the topic's last reply's posted date. So that topics with newer replies pop back to the top of the list. This is rather simple if I knew that every topic had at least one reply; I would just do this: var topicsQuery = from x in board.Topics orderby x.Replies.Last().PostedDate descending select x; However, in many cases the topic has no replies. In which case I would like to use the topic's posted date instead. Is there a way within my linq query to order by x.PostedDate in the event that the topic has no replies? I'm getting confused by this and any help would be appreciated. With the above query, it breaks on topics with no replies because of the x.Replies.Last() which assumes there are replies. LastOrDefault() doesn't work because I need to access the PostedDate property which also assumes a reply exists. Thanks in advance for any insight.

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