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  • Questions on Juval Lowy's IDesign C# Coding Standard

    - by Jan
    We are trying to use the IDesign C# Coding standard. Unfortunately, I found no comprehensive document to explain all the rules that it gives, and also his book does not always help. Here are the open questions that remain for me (from chapter 2, Coding Practices): No. 26: Avoid providing explicit values for enums unless they are integer powers of 2 No. 34: Always explicitly initialize an array of reference types using a for loop No. 50: Avoid events as interface members No. 52: Expose interfaces on class hierarchies No. 73: Do not define method-specific constraints in interfaces No. 74: Do not define constraints in delegates Here's what I think about those: I thought that providing explicit values would be especially useful when adding new enum members at a later point in time. If these members are added between other already existing members, I would provide explicit values to make sure the integer representation of existing members does not change. No idea why I would want to do this. I'd say this totally depends on the logic of my program. I see that there is alternative option of providing "Sink interfaces" (simply providing already all "OnXxxHappened" methods), but what is the reason to prefer one over the other? Unsure what he means here: Could this mean "When implementing an interface explicitly in a non-sealed class, consider providing the implementation in a protected virtual method that can be overridden"? (see Programming .NET Components 2nd Edition, end of chapter “Interfaces and Class Hierarchies”). I suppose this is about providing a "where" clause when using generics, but why is this bad on an interface? I suppose this is about providing a "where" clause when using generics, but why is this bad on a delegate?

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  • Save object in CoreData

    - by John
    I am using CoreData with iPhone SDK. I am making a notes app. I have a table with note objects displayed from my model. When a button is pressed I want to save the text in the textview to the object being edited. How do I do this? I've been trying several things but none seem to work. Thanks EDIT: NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity]; NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context]; [newManagedObject setValue:detailViewController.textView.text forKey:@"noteText"]; NSError *error; if (![context save:&error]) { /* Replace this implementation with code to handle the error appropriately. abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. */ NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } The above code saves it correctly but it saves it as a new object. I want it to be saved as the one I have selected in my tableView.

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  • Better language or checking tool?

    - by rwallace
    This is primarily aimed at programmers who use unmanaged languages like C and C++ in preference to managed languages, forgoing some forms of error checking to obtain benefits like the ability to work in extremely resource constrained systems or the last increment of performance, though I would also be interested in answers from those who use managed languages. Which of the following would be of most value? A language that would optionally compile to CLR byte code or to machine code via C, and would provide things like optional array bounds checking, more support for memory management in environments where you can't use garbage collection, and faster compile times than typical C++ projects. (Think e.g. Ada or Eiffel with Python syntax.) A tool that would take existing C code and perform static analysis to look for things like potential null pointer dereferences and array overflows. (Think e.g. an open source equivalent to Coverity.) Something else I haven't thought of. Or put another way, when you're using C family languages, is the top of your wish list more expressiveness, better error checking or something else? The reason I'm asking is that I have a design and prototype parser for #1, and an outline design for #2, and I'm wondering which would be the better use of resources to work on after my current project is up and running; but I think the answers may be useful for other tools programmers also. (As usual with questions of this nature, if the answer you would give is already there, please upvote it.)

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  • Using git svn with some awkward permissions

    - by Migs
    Due to some funky permissions on our client's side that we can't change, we have a project whose hierarchy looks something like: projectname/trunk: foo/, bar/, baz/ projectname/branches: branch1/, branch2/ (where branch1 and branch2 each contain foo, bar, and baz.) The thing is, I have no permission to access trunk, so I can't just do a clone of project/trunk. I do have permission to access branches. What I am currently doing is checking out each subdirectory individually via git svn clone, so that each one has their own git repo. I use a script to update/commit them all, but what I would prefer to do is to check them all out under a single repo, and be able to commit changes with a single call to git svn dcommit. Is this possible? I mentioned the branches hierarchy because if possible, I'd also like to be able to track the branches the way I could if the permissions were more sane. I've tried permuting a lot of options that sounded useful, but I haven't found one that gives me exactly what I want. I sense that the solution may have something to do with --no-minimize-url, but I'm not even sure about that, as it didn't help me when I tried it.

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  • FluentNHibernate: multiple one-to-many relationships between the same entities.

    - by Venemo
    Hi, I'm working on a bug tracking application. There are tickets, and each ticket has an opener user and an assigned user. So, basically, I have two entities, which have two many-to-one relationships with each other. Their schematic is this: User: public class User { public virtual int Id { get; private set; } ... public virtual IList<Ticket> OpenedTickets { get; set; } public virtual IList<Ticket> AssignedTickets { get; set; } } Ticket: public class Ticket { public virtual int Id { get; protected set; } ... [Required] public virtual User OpenerUser { get; set; } public virtual User AssignedUser { get; set; } } I use FluentNHibernate's auto mapping feature. The problem is, that no matter whether relationship I set, on the side of the User, both collections always contain the same data. I guess Fluent can't tell which end of which relationship belongs to where. I googled around but haven't found anything useful. Could anyone help me, please?

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  • SQL Server 2008 R2

    - by kevchadders
    Hi all, I heard on the grapevine that Microsoft will be releasing SQL Server 2008 R2 within a year. Though I initially thought this was a patch for the just released 2008 version, I realised that it’s actually a completely different version that you would have to pay for. (Am I correct, if you had SQL Server 2008, would you have to pay again if you wanted to upgrade to 2008 R2?) If you’re already running SQL Server 2008, would you say it’s still worth the upgrade? Or does it depend on the size of your company and current setup. For what I’ve initially read, I do get the impression that this version would be more useful for the very high end hardware setup where you want to have very good scalability. With regard to programming, is there any extra enhancements/support in there which you’re aware of that will significantly help .NET Products/Web Development? Initially found a couple of links on it, but I was wondering if anyone had anymore info to share on subject as I couldn’t find nothing on SO about it? Thanks. New SQL Server R2 Microsoft Link on it. Microsoft SQL 2008 R2 EDIT: More information based on the Express Edition One very interesting thing about SQL Server 2008 R2 concerns the Express edition. Previous express versions of SQL Server Express had a database size limit of 4GB. With SQL Server Express 2008 R2, this has now been increased to 10GB !! This now makes the FREE express edition a much more viable option for small & medium sized applications that are relatively light on database requirements. Bear in mind, that this limit is per database, so if you coded your application cleverly enough to use a separate database for historical/archived data, you could squeeze even more out of it! For more information, see here: http://blogs.msdn.com/sqlexpress/archive/2010/04/21/database-size-limit-increased-to-10gb-in-sql-server-2008-r2-express.aspx

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  • ForEach loop in Mathematica.

    - by dreeves
    I'd like something like this: ForEach[i_, {1,2,3}, Print[i] ] Or, more generally, to destructure arbitrary stuff in the list you're looping over, like: ForEach[{i_, j_}, {{1,10}, {2,20}, {3,30}}, Print[i*j] ] (Meta-question: is that a good way to call a ForEach loop, with the first argument a pattern like that?) ADDED: Some answerers have rightly pointed out that usually you want to use Map or other purely functional constructs and eschew a non-functional programming style where you use side effects. I agree! But here's an example where I think this ForEach construct is supremely useful: Say I have a list of options (rules) that pair symbols with expressions, like attrVals = {a -> 7, b -> 8, c -> 9} Now I want to make a hash table where I do the obvious mapping of those symbols to those numbers. I don't think there's a cleaner way to do that than ForEach[a_ -> v_, attrVals, h[a] = v] ADDED: I just realized that to do ForEach properly, it should support Break[] and Continue[]. I'm not sure how to implement that. Perhaps it will need to somehow be implemented in terms of For, While, or Do since those are the only loop constructs that support Break[] and Continue[]. If anyone interested in this wants to ask about that as a separate question, please do!

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  • How to mock/stub a directory of files and their contents using RSpec?

    - by John Topley
    A while ago I asked "How to test obtaining a list of files within a directory using RSpec?" and although I got a couple of useful answers, I'm still stuck, hence a new question with some more detail about what I'm trying to do. I'm writing my first RubyGem. It has a module that contains a class method that returns an array containing a list of non-hidden files within a specified directory. Like this: files = Foo.bar :directory => './public' The array also contains an element that represents metadata about the files. This is actually a hash of hashes generated from the contents of the files, the idea being that changing even a single file changes the hash. I've written my pending RSpec examples, but I really have no idea how to implement them: it "should compute a hash of the files within the specified directory" it "shouldn't include hidden files or directories within the specified directory" it "should compute a different hash if the content of a file changes" I really don't want to have the tests dependent on real files acting as fixtures. How can I mock or stub the files and their contents? The gem implementation will use Find.find, but as one of the answers to my other question said, I don't need to test the library. I really have no idea how to write these specs, so any help much appreciated!

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  • class modifier issues in C# with "private" classes

    - by devoured elysium
    I had a class that had lots of methods: public class MyClass { public bool checkConditions() { return checkCondition1() && checkCondition2() && checkCondition3(); } ...conditions methods public void DoProcess() { FirstPartOfProcess(); SecondPartOfProcess(); ThirdPartOfProcess(); } ...process methods } I identified two "vital" work areas, and decided to extract those methods to classes of its own: public class MyClass { private readonly MyClassConditions _conditions = new ...; private readonly MyClassProcessExecution = new ...; public bool checkConditions() { return _conditions.checkConditions(); } public void DoProcess() { _process.DoProcess(); } } In Java, I'd define MyClassConditions and MyClassProcessExecution as package protected, but I can't do that in C#. How would you go about doing this in C#? Setting both classes as inner classes of MyClass? I have 2 options: I either define them inside MyClass, having everything in the same file, which looks confusing and ugly, or I can define MyClass as a partial class, having one file for MyClass, other for MyClassConditions and other for MyClassProcessExecution. Defining them as internal? I don't really like that much of the internal modifier, as I don't find these classes add any value at all for the rest of my program/assembly, and I'd like to hide them if possible. It's not like they're gonna be useful/reusable in any other part of the program. Keep them as public? I can't see why, but I've let this option here. Any other? Name it! Thanks

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  • Run FFmpeg from Shell Script

    - by Abs
    Hello all, I have found a useful shell script that shows all files in a directory recursively. Where it prints the file name echo "$i"; #Display File name. I would instead like to run an ffmpeg command on non MP3 files, how can I do this? I have very limited knowledge of shell scripts so I appreciate if I was spoon fed! :) //if file is NOT MP3 ffmpeg -i [the_file] -sameq [same_file_name_with_mp3_extension] //delete old file Here is the shell script for reference. DIR="." function list_files() { if !(test -d "$1") then echo $1; return; fi cd "$1" echo; echo `pwd`:; #Display Directory name for i in * do if test -d "$i" #if dictionary then list_files "$i" #recursively list files cd .. else echo "$i"; #Display File name fi done } if [ $# -eq 0 ] then list_files . exit 0 fi for i in $* do DIR="$1" list_files "$DIR" shift 1 #To read next directory/file name done

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  • Calculating distance between two X,Y coordinates

    - by Umopepisdn
    I am writing a tool for a game that involves calculating the distance between two coordinates on a spherical plane 500 units across. That is, [0,0] through [499,499] are valid coordinates, and [0,0] and [499,499] are also right next to each other. Currently, in my application, I am comparing the distance between a city with an [X,Y] location respective to the user's own [X,Y] location, which they have configured in advance. To do this, I found this algorithm, which kind of works: Math.sqrt ( dx * dx + dy * dy ); Because sorting a paged list by distance is a useful thing to be able to do, I implemented this algorithm in a MySQL query and have made it available to my application using the following part of my SELECT statement: SQRT( POW( ( ".strval($sourceX)." - cityX ) , 2 ) + POW( ( ".strval($sourceY)." - cityY ) , 2 ) ) AS distance This works fine for many calculations, but does not take into account the fact that [0,0] and [499,499] are kitty-corner to one another. Is there any way I can tweak this algorithm to generate an accurate distance, given that 0 and 499 are adjacent? Thanks, -Umo

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  • Managing My Database in Source Control

    - by Jason
    As I am working with a new database project (within VS2008), and as I have never developed a database from scratch, I immediately began looking into how to manage a database within source control (in this case, Subversion). I found some information on SO, including this post: Keeping development databases in multiple environments in sync. One of the answers in particular pointed to a number of a links, all of which had good, useful information. I was reading a series of posts by K. Scott Allen which describe how he manages database change. From my reading (and please pardon the noobishness of my question), it seems as though the database itself is never checked into a repository. Rather, scripts that can build the database, along with test data (which is also populated from scripts) is checked into the repository. Ultimately, this means that, when a developer is testing his or her app, these scripts, which are part of the build process, are run. This ensures that the database is up-to-date, but is also run locally from every developer's machine. This makes sense to me (if I am indeed reading that correctly). However, if I am missing something, I would appreciate correction or additional guidance. In addition, another question I wanted to ask - does this also mean that I should NOT check in the mdf or ldf files that are created from Visual Studio? Thanks for any help and additional insight. Always appreciated.

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  • Can I get a reference to an object created in a jQuery plugin?

    - by gargantaun
    Perhaps my brain is fried, but I'm writing a plugin that created an tweaks an element, but also creates an object that i'd like access to. So the plugin looks like this (function ($) { $.fn.myPlugin = function () { return this.each(function () { // do some stuff to the element... this.objectInstance = new usefulObject(); }); }; })(jQuery); function usefulObject(){ // useful object properties and methods.... this.doSomething = function(){ alert("Don't google Google. You'll break the internet."); } } so when I call the plugin, I also want to be able to get access to that usefulObject that I created. I thought something like this might work.... tweakedElement = $("#someDiv").myPlugin(); tweakedElement.objectInstance.doSomething(); ... but that's not working. How can I achieve this? Can I achieve this? Answers on a postcard, or down below, whichever suits you.

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  • Make function declarations based on function definitions

    - by Clinton Blackmore
    I've written a .cpp file with a number of functions in it, and now need to declare them in the header file. It occurred to me that I could grep the file for the class name, and get the declarations that way, and it would've worked well enough, too, had the complete function declaration before the definition -- return code, name, and parameters (but not function body) -- been on one line. It seems to me that this is something that would be generally useful, and must've been solved a number of times. I am happy to edit the output and not worried about edge cases; anything that gives me results that are right 95% of the time would be great. So, if, for example, my .cpp file had: i2cstatus_t NXTI2CDevice::writeRegisters( uint8_t start_register, // start of the register range uint8_t bytes_to_write, // number of bytes to write uint8_t* buffer = 0) // optional user-supplied buffer { ... } and a number of other similar functions, getting this back: i2cstatus_t NXTI2CDevice::writeRegisters( uint8_t start_register, // start of the register range uint8_t bytes_to_write, // number of bytes to write uint8_t* buffer = 0) for inclusion in the header file, after a little editing, would be fine. Getting this back: i2cstatus_t writeRegisters( uint8_t start_register, uint8_t bytes_to_write, uint8_t* buffer); or this: i2cstatus_t writeRegisters(uint8_t start_register, uint8_t bytes_to_write, uint8_t* buffer); would be even better.

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  • How can I avoid encoding mixups of strings in a C/C++ API?

    - by Frerich Raabe
    I'm working on implementing different APIs in C and C++ and wondered what techniques are available for avoiding that clients get the encoding wrong when receiving strings from the framework or passing them back. For instance, imagine a simple plugin API in C++ which customers can implement to influence translations. It might feature a function like this: const char *getTranslatedWord( const char *englishWord ); Now, let's say that I'd like to enforce that all strings are passed as UTF-8. Of course I'd document this requirement, but I'd like the compiler to enforce the right encoding, maybe by using dedicated types. For instance, something like this: class Word { public: static Word fromUtf8( const char *data ) { return Word( data ); } const char *toUtf8() { return m_data; } private: Word( const char *data ) : m_data( data ) { } const char *m_data; }; I could now use this specialized type in the API: Word getTranslatedWord( const Word &englishWord ); Unfortunately, it's easy to make this very inefficient. The Word class lacks proper copy constructors, assignment operators etc.. and I'd like to avoid unnecessary copying of data as much as possible. Also, I see the danger that Word gets extended with more and more utility functions (like length or fromLatin1 or substr etc.) and I'd rather not write Yet Another String Class. I just want a little container which avoids accidental encoding mixups. I wonder whether anybody else has some experience with this and can share some useful techniques. EDIT: In my particular case, the API is used on Windows and Linux using MSVC 6 - MSVC 10 on Windows and gcc 3 & 4 on Linux.

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  • Python lists/arrays: disable negative indexing wrap-around

    - by wim
    While I find the negative number wraparound (i.e. A[-2] indexing the second-to-last element) extremely useful in many cases, there are often use cases I come across where it is more of an annoyance than helpful, and I find myself wishing for an alternate syntax to use when I would rather disable that particular behaviour. Here is a canned 2D example below, but I have had the same peeve a few times with other data structures and in other numbers of dimensions. import numpy as np A = np.random.randint(0, 2, (5, 10)) def foo(i, j, r=2): '''sum of neighbours within r steps of A[i,j]''' return A[i-r:i+r+1, j-r:j+r+1].sum() In the slice above I would rather that any negative number to the slice would be treated the same as None is, rather than wrapping to the other end of the array. Because of the wrapping, the otherwise nice implementation above gives incorrect results at boundary conditions and requires some sort of patch like: def ugly_foo(i, j, r=2): def thing(n): return None if n < 0 else n return A[thing(i-r):i+r+1, thing(j-r):j+r+1].sum() I have also tried zero-padding the array or list, but it is still inelegant (requires adjusting the lookup locations indices accordingly) and inefficient (requires copying the array). Am I missing some standard trick or elegant solution for slicing like this? I noticed that python and numpy already handle the case where you specify too large a number nicely - that is, if the index is greater than the shape of the array it behaves the same as if it were None.

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  • C# Sql Connection Best Practises 2013

    - by Pete Petersen
    With the new year approaching I'm drawing up a development plan for 2013. I won't bore you with the details but I started thinking about whether the way I do things is actually the 'correct' way. In particular how I'm interfacing with SQL. I create predominantly create WPF desktop applications and often some Silverlight Web Applications. All of my programs are very Data-Centric. When connecting to SQL from WPF I tend to use Stored Procedures stored on the server and fetch them using ADO.NET (e.g. SQLConnection(), .ExecuteQuery()). However with Silverlight I have a WCF service and use LINQ to SQL (and I'm using LINQ much more in WPF). My question is really is am I doing anything wrong in a sense that it's a little old fashioned? I've tried to look this up online but could find anything useful after about 2010 and of those half were 'LINQ is dead!' and the other 'Always use LINQ' Just want to make sure going forward I'm doing the right things the right way, or at least the advised way :). What principles are you using when connecting to SQL? Is it the same for WPF and Silverlight/WCF?

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  • POST method getting converted to GET in IE-9

    - by Sri127
    I have this line of code in my JSP. (I'm using struts 1.3) <html:form action="screening/mine.do" method="post"> . . . </html:form When the action corresponding to mine.do is invoked (using struts-config.xml), the page is getting submitted as GET instead of POST. All the request parameters including the required ones are getting lost due to this. This issue occcurs only in IE-9. The response remains as POST when I use other versions of IE or any other browsers. How do I make the response to remain as POST in IE-9 ? EDIT : I observed one more issue in this. Whenever the page is rendered in a new window, this issue occurs. Other places, the POST works fine in IE-9. Also, this issue occurs in Win7/IE-8, but works absolutely fine in XP/IE-8. Is there something to do with the OS as well??? Any solutions would be useful. Thanks!!

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  • Looking for an email template engine for end-users ...

    - by RizwanK
    We have a number of customers that we have to send monthly invoices too. Right now, I'm managing a codebase that does SQL queries against our customer database and billing database and places that data into emails - and sends it. I grow weary of maintaining this every time we want to include a new promotion or change our customer service phone numbers. So, I'm looking for a replacement to move more of this into the hands of those requesting the changes. In my ideal world, I need : A WYSIWYG (man, does anyone even say that anymore?) email editor that generates templates based upon the output from a Database Query. The ability to drag and drop various fields from the database query into the email template. Display of sample email results with the database query. Web application, preferably not requiring IIS. Involve as little code as possible for the end-user, but allow basic functionality (i.e. arrays/for loops) Either comes with it's own email delivery engine, or writes output in a way that I can easily write a Python script to deliver the email. Support for generic Database Connectors. (I need MSSQL and MySQL) F/OSS So ... can anyone suggest a project like this, or some tools that'd be useful for rolling my own? (My current alternative idea is using something like ERB or Tenjin, having them write the code, but not having live-preview for the editor would suck...)

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  • C# SQL Data Adapter Fill on existing typed Dataset

    - by René
    I have an option to choose between local based data storing (xml file) or SQL Server based. I already created a long time ago a typed dataset for my application to save data local in the xml file. Now, I have a bool that changes between Server based version and local version. If true my application get the data from the SQL Server. I'm not sure but It seems that Sql Adapter's Fill Method can't fill the Data in my existing schema SqlCommand cmd = new SqlCommand("Select * FROM dbo.Categories WHERE CatUserId = 1", _connection); cmd.CommandType = CommandType.Text; _sqlAdapter = new SqlDataAdapter(cmd); _sqlAdapter.TableMappings.Add("Categories", "dbo.Categories"); _sqlAdapter.Fill(Program.Dataset); This should fill my data from dbo.Categories to Categories (in my local, typed dataset). but it doesn't. It creates a new table with the name "Table". It looks like it can't handle the existing schema. I can't figure it out. Where is the problem? btw. of course the database request I do isn't very useful that way. It's just a simplified version for testing...

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  • c++ and visual studio 08, how to develop the following web extracting application. folloow up of las

    - by user287745
    the purpose is to use c++ in a useful way. i have just started programming and have made a few small applications in c and c#. my understanding is that programming for web and thing related to web is now a days a very easy task. please note this is for personnel learning not for rent a coder or any money making. an application which can run on any windows platform even win98. the application should start automatically at a scheduled time and do the following. connect to a site which displays stock prices summary (high low current open ). captures the data (excluding the other things in the site) and saves it to disk ( a sql database) please note:- internet connection is assumed to be there always. do not want to know how to make database schema or database. the stock exchange has no law prohibiting the use of the data provided on its site, but i do not want to mention the name in case i am wrong, but its for personnel private use only. the data of summary of pricing is arranged in a table such that when copied pasted to ms excel it automatically forms a table. guidance needed thank u.

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  • What are the interets of synthetic methods?

    - by romaintaz
    Problem One friend suggested an interesting problem. Given the following code: public class OuterClass { private String message = "Hello World"; private class InnerClass { private String getMessage() { return message; } } } From an external class, how may I print the message variable content? Of course, changing the accessibility of methods or fields is not allowed. (the source here, but it is a french blog) Solution The code to solve this problem is the following: try { Method m = OuterClass.class.getDeclaredMethod("access$000", OuterClass.class); OuterClass outerClass = new OuterClass(); System.out.println(m.invoke(outerClass, outerClass)); } catch (Exception e) { e.printStackTrace(); } Note that the access$000 method name is not really standard (even if this format is the one that is strongly recommanded), and some JVM will name this method access$0. Thus, a better solution is to check for synthetic methods: Method method = null; int i = 0; while ((method == null) && (i < OuterClass.class.getDeclaredMethods().length)) { if (OuterClass.class.getDeclaredMethods()[i].isSynthetic()) { method = OuterClass.class.getDeclaredMethods()[i]; } i++; } if (method != null) { try { System.out.println(method.invoke(null, new OuterClass())); } catch (Exception e) { e.printStackTrace(); } } So the interesting point in this problem is to highlight the use of synthetic methods. With these methods, I can access a private field as it was done in the solution. Of course, I need to use reflection, and I think that the use of this kind of thing can be quite dangerous... Question What is the interest - for me, as a developer - of a synthetic method? What can be a good situation where using the synthetic can be useful?

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  • Why can't we just use a hash of passphrase as the encryption key (and IV) with symmetric encryption algorithms?

    - by TX_
    Inspired by my previous question, now I have a very interesting idea: Do you really ever need to use Rfc2898DeriveBytes or similar classes to "securely derive" the encryption key and initialization vector from the passphrase string, or will just a simple hash of that string work equally well as a key/IV, when encrypting the data with symmetric algorithm (e.g. AES, DES, etc.)? I see tons of AES encryption code snippets, where Rfc2898DeriveBytes class is used to derive the encryption key and initialization vector (IV) from the password string. It is assumed that one should use a random salt and a shitload of iterations to derive secure enough key/IV for the encryption. While deriving bytes from password string using this method is quite useful in some scenarios, I think that's not applicable when encrypting data with symmetric algorithms! Here is why: using salt makes sense when there is a possibility to build precalculated rainbow tables, and when attacker gets his hands on hash he looks up the original password as a result. But... with symmetric data encryption, I think this is not required, as the hash of password string, or the encryption key, is never stored anywhere. So, if we just get the SHA1 hash of password, and use it as the encryption key/IV, isn't that going to be equally secure? What is the purpose of using Rfc2898DeriveBytes class to generate key/IV from password string (which is a very very performance-intensive operation), when we could just use a SHA1 (or any other) hash of that password? Hash would result in random bit distribution in a key (as opposed to using string bytes directly). And attacker would have to brute-force the whole range of key (e.g. if key length is 256bit he would have to try 2^256 combinations) anyway. So either I'm wrong in a dangerous way, or all those samples of AES encryption (including many upvoted answers here at SO), etc. that use Rfc2898DeriveBytes method to generate encryption key and IV are just wrong.

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  • How to create anroid to send to work in my place?

    - by aj-sin-dhal
    Hi I would like to create a life like android/robot to send to work in my place. Requirements 1) People should not be able to tell the difference between me and the android. My first attempt may not be perfect but I can tell people that its my twin that was dropped on its head while we were growing up. 2) Should have the same weight as me so it won't crush small children if it falls over. By small children I mean those above 7 years old. Those below 7 can easily be crushed by a normal human adult so it is not important to consider that special case. 3) Should run on linux. I have a tight budget and cannot afford to pay for any propreitary operating system. Will consider writing my own operating system if this is the best way to go. I am reading "The design of the unix operating system" by Maurice J. Bach currently. That should be useful. I also have an old copy of the dragon book. What other books should I read? I would like to finish this by monday if possible. I don't like working on mondays. I have made a start and have picked some clothes and shoes for my android worker. Any help will be appreciated. This is a serious question. AJ

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  • Question about array subscripting in C#

    - by Michael J
    Back in the old days of C, one could use array subscripting to address storage in very useful ways. For example, one could declare an array as such. This array represents an EEPROM image with 8 bit words. BYTE eepromImage[1024] = { ... }; And later refer to that array as if it were really multi-dimensional storage BYTE mpuImage[2][512] = eepromImage; I'm sure I have the syntax wrong, but I hope you get the idea. Anyway, this projected a two dimension image of what is really single dimensional storage. The two dimensional projection represents the EEPROM image when loaded into the memory of an MPU with 16 bit words. In C one could reference the storage multi-dimensionaly and change values and the changed values would show up in the real (single dimension) storage almost as if by magic. Is it possible to do this same thing using C#? Our current solution uses multiple arrays and event handlers to keep things synchronized. This kind of works but it is additional complexity that we would like to avoid if there is a better way.

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