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  • Is OOP based on any branch of mathematics?

    - by ektrules
    I know relational databases are based on set-theory, functional programming is based on lambda calculus, logic programming is based on logic (of course :)), and now that I think of it; I'm not sure if imperative and generic programming is based on any particular branch of mathematics either.

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  • Race condition for thread startup

    - by Ozzah
    A similar question was asked here, but the answers generally all seem to relate to the lambda notation. I get a similar result without the lambda so I thought I'd ask for some clarification: Say I have something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); One would expect the following output: Thread 0 Thread 1 Thread 2 Thread 3 Thread 4 Now I realise that the threads aren't started in any particular order, so let's just assume that the above lines can come out in any order. But that is not what happens. What instead happens: Thread 3 Thread 4 Thread 4 Thread 4 Thread 4 or something similar, which leads me to believe that rather than passing the value if i, it is passing the reference. (Which is weird, since an int is a value type). Doing something like this: for (int i = 0; i < 5; i++) (new Thread(new ThreadStart(delegate() { int j = i; Console.WriteLine("Thread " + j); }))).Start(); does not help either, even though we have made a copy of i. I am assuming the reason is that it hasn't made a copy of i in time. Doing something like this: for (int i = 0; i < 5; i++) { (new Thread(new ThreadStart(delegate() { Console.WriteLine("Thread " + i); }))).Start(); Thread.Sleep(50); } seems to fix the problem, however it is extremely undesirable as we're wasting 50ms on each iteration, not to mention the fact that if the computer is heavily loaded then maybe 50ms may not be enough. Here is a sample with my current, specific problem: Thread t = new Thread(new ThreadStart(delgate() { threadLogic(param1, param2, param3, param4); })); t.Start(); param1 = param2 = param3 = param4 = null; with: void threadLogic(object param1, object param2, object param3, object param4) { // Do some stuff here... } I want threadLogic() to run in its own thread, however the above code gives a null reference exception. I assume this is because the values are set to null before the thread has had a chance to start. Again, putting a Thread.Sleep(100) works, but it is an awful solution from every aspect. What do you guys recommend for this particular type of race condition?

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  • Parsing a comma-separated list

    - by alex
    I have a comma-separated list of values, for example: strins s = "param1=true;param2=4;param3=2.0f;param4=sometext;"; I need a functions: public bool ExtractBool(string parameterName, string @params); public int ExtractInt(string parameterName, string @params); public float ExtractFloat(string parameterName, string @params); public string ExtractString(string parameterName, string @params); Is there a special functions in .net that can help me with csl ? PS: parameter names are equal within a list.

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  • Creating an enum/class from a Database Table

    - by Mark
    I have a database table that essentially contains different types of things. I'll use animals as an example. I have a table called AnimalTypes: AnimalTypes { ID:int, Name:string } I then populate it with: 1:Dog, 2:Cat, 3:Fish I would like to then have some sort of C# object created that functions similar to this enum be entirely read from the database: enum AnimalTypes { Dog = 1, Cat = 2, Fish = 3 } Is there a way to create an enum/class from a database table as described? I basically want to be able to reference things in the AnimalTypes table using intellisense and AnimalTypes.Dog as an example; I don't actually need an enum, just something that kind of functions like one. Is this possible? Edit: I'm not really that thrilled about generating a DLL as I've seen in other related problems. I feel like this should be possible with reflection.

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  • How to create a new IDA project based on an existing one with different offsets?

    - by tbergelt
    I have an existing IDA Pro project for a C166 processor embedded application. This project already has many functions, variables, etc defined. There are different versions of the embedded application I am looking at. The different versions of the application are 99% the same, but with slight variations in code and data that cause functions and variables to be at different memory offsets. I want to create a new IDA project for a different version of the application. I would like to somehow import all of my function and variable definitions from my existing IDA project. I would like IDA to recognize the signatures of the existing function definitions and define them at there new location in the new project. How can I do this? Are there certain plugins for IDA I can chain together?

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  • Rails: three most recent records by unique belongs_to associated record

    - by Dennis Collective
    class User has_many :comments end class Comment belongs_to :user named_scope :recent, :order => 'comments.created_at DESC' named_scope :limit, lambda { |limit| {:limit => limit}} named_scope :by_unique_users end what would I put in the :by_unique_users so that I can do Comment.recent.by_unique_users.limit(3), and only get one comment per user on sqlite named_scope :by_unique_user, :group = "user_id" works, but makes it freak out on postgres, which is deployed on production PGError: ERROR: column "comments.id" must appear in the GROUP BY clause or be used in an aggregate function

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  • Parsing NTFS Partition in C

    - by DooriBar
    Hello all, I'm just a beginner and I have a need to parse a NTFS partition for the purpose of extracting Security Descriptors. (I been trying to use the native functions of the Windows API, but my conclusion is that something is seriously wrong with the functions' behavior, or their documentation.) I was wondering if anybody here experienced with such requirement, and could give me few hints, references, guidance... where to begin? (I've found www.ntfs.com, seems to have NTFS structure information, but I'm afraid I'll need something more to get started...) My intention is to use it under Windows XP. Thanks in advanced, Doori Bar

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  • interactive lua prompt in opengl application

    - by anon
    Okay, so when I run lua, I get something like: lua Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio > Now, I want a prompt like this, 1) in a GUI application I've written. My GUI application can provide functions like: get_input_from_screen(); and write_this_crap_out_to_screen(); and more functions I can write as necessary I also know how to embed a lua interpreter in my C++ code (short tutorial on the web) What I don't know .. is how to connect the input/output of a lua interpreter with my GUI stuff. Any help/links apreciated. Thanks!

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  • Why doesn't MySQL support millisecond / microsecond precision?

    - by Byron Whitlock
    So I just found the most frustrating bug ever in MySQL. Apparently the TIMESTAMP field, and supporting functions do not support any greater precision than seconds!? So I am using PHP and Doctrine, and I really need those microseconds (I am using the actAs: [Timestampable] property). I found a that I can use a BIGINT field to store the values. But will doctrine add the milliseconds? I think it just assigns NOW() to the field. I am also worried the date manipulation functions (in SQL) sprinkled through the code will break. I also saw something about compiling a UDF extension. This is not an acceptable because I or a future maintainer will upgrade and poof, change gone. Has anyone found a suitable workaround?

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  • Identifying a function call in a python script line in runtime

    - by Dani
    I have a python script that I run with 'exec'. The script's string has calls to functions. When a function is called, I would like it to know the line number and offset in line for that call in the script (in the string I fed exec with). Here is an example. If my script is: foo1(); foo2(); foo1() foo3() And if I have code that prints (line,offset) in every function, I should get (0,0), (0,8), (0,16), (1,0) In most cases this can be easily done by getting the stack frame, because it contains the line number and the function name. The only problem is when there are two functions with the same name in a certain line. Unfortunately this is a common case for me. Any ideas?

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  • small & readable scheme interpreter in C++ ?

    - by anon
    Anyone know of a good / small scheme interpreter in C++? Perferably something < 2000 LOC, with a simple garbage collectro (either compacting or mark & sweep), no need to support all of R5RS, just basics of if/lambda/set!/cons/car/cdr and some basic operations. Thanks!

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  • Django, javascript and code ruse problem

    - by dragoon
    Hi, I have some sort of a design problem with my Django AJAX application. I have a template where I initialize js variable from django context variable like so: var test = "{{ test }}"; This variable is than used in a number of js functions that are needed for interface to work properly. So now I'm trying to reuse some content from this page in another page that loads it dynamically on some user interaction using jQuery.load(..), and I don't see any way how I can initialize that variable, so js functions don't work now. Is there any solution for this or may be I'm doing it wrong? Thanks.

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  • Best way to map/join two autogenerated enums

    - by tomlip
    What is the best C++ (not C++11) way of joining two enums from autogenerated class similar to one presented below: namespace A { namespace B { ... class CarInfo { enum State { // basically same enums defined in different classes Running, Stopped, Broken } } class BikeInfo { enum State { // basically same enums defined in different classes Running, Stopped, Broken } } } } What is needed is unified enum State for both classes that is seen to outside world alongside with safe type conversion. The best and probably most straightforward way I came up with is to create external enum: enum State { Running, Stopped, Broken } together with conversion functions State stateEnumConv(A::B::CarInfo::State aState); State stateEnumConv(A::B::BikeInfo::State aState); A::B::CarInfo::State stateEnumConv(State aState); A::B::BikeInfo::State stateEnumConv(State aState); Direction into right approach is needed. Gosh coming from C I hate those long namespaces everywhere an I wish it could be only A::B level like in presented example. Four conversion functions seem redundant note that CarInfo::State and BikeInfo::State has same enum "members".

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  • Multiple-File Template Implementation

    - by Maxpm
    With normal functions, the declaration and definition are often separated across multiple files like so: // Foo.h namespace Foo { void Bar(); } . // Foo.cpp #include "Foo.h" void Foo::Bar() { cout << "Inside function." << endl; } It is my understanding that this cannot be done with templates. The declaration and definition must not be separate because the appropriate form of the template is created "on-demand" when needed. So, how and where are templates typically defined in a multiple-file project like this? My intuition is that it would be in Foo.cpp because that's where the "meat" of functions normally is, but on the other hand it's the header file that's going to be included.

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  • RegEx (or other) parsing of script

    - by jpmyob
    RegEx is powerful - it is tru but I have a little - query for you I want to parse out the FUNCTIONS from some old code in JS...however - I am RegEx handicapped (mentally deficient in grasping the subtleties).. the issue that makes me NOT EVEN TRY - is two fold - 1) myVar = function(x){ yadda yadda } AND function myVar(x) { yadda yadda } are found throuout - COLD I write a parser for each? sure - but that seems inefficient... 2) MANY things may reside INSIDE the {} including OTHER sets of {} or other Functions(){} block of text... HELP - does anyone have, or know of some code parsing snippets or examples that will parse out the info I want to collect? Thanks

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  • How do I include 3rd party libraries in my code...

    - by Krakkos
    I understand the process of using a 3rd party library to access functions outside of my code base, but how do i actually set up Visual Studio 2005 to include them in the project. I have a 3rd party library with some headers, some cpp's, and some .lib files. In the projects properties I add the top level external library directory as an include directory, I add the additional library directory at the same level put this is project properties too. In the .cpp file where I use the functions, do I put the #include in its header file? In the top level projects header file? in the cpp? I've tried all that, but I get "unresolved external symbol"... grrrrrrrrrrrrr

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  • Approaching Java from a Ruby perspective

    - by Travis
    There are plenty of resources available to a Java developer for getting a jump-start into Ruby/Rails development. The reverse doesn't appear to be true. What resources would you suggest for getting up-to-date on the current state of java technologies? How about learning how to approach DRY (don't repeat yourself) without the use of metaprogramming? Or how to approach various scenarios where a ruby developer is used to passing in a function (proc/lambda/block) as an argument (callbacks, etc)?

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  • Any PHP MVC framework planning to use 5.3 features?

    - by alexandrul
    I would like to get started with PHP, and 5.3 release seems to bring many nice features (namespaces, lambda functions, and many others). I have found some MVC frameworks, and some of them support only PHP 5: PHP Frameworks PHP MVC Frameworks Model–view–controller on Wikipedia but can anyone recommend one of those MVC frameworks that plans to actively use PHP 5.3 features, not just being compatible with PHP 5.3? Update Results so far: Zend Framework 2.0 (in development) Lithium (in development, based on CakePHP) Symfony (in development) FLOW3 (in development, alpha)

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  • why don't more programming languages have builtin interfaces to the window manager?

    - by Naveen
    Programming is at the heart about automating tasks on a computer. Presumably those tasks would normally be done manually by a human. Humans use the computer through the keyboard, mouse, and interaction with the console or the window manager. But very few languages have built in functions that provide an interface to these basic computing objects. A notable exception is autohotkey, an open source language on windows, providing builtin functions that allow the following simple tasks: * Get Pixel Information * Get mouse position * Keyboard macros * Simulate key strokes * Simulate mouse click * Window management See examples on rosettacode. There have been various attempts on linux, many of which were stopped without explanation. One is the inactive tcl library: android. Search google code for android, lang:tcl

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  • Using .dll methods to load data from file in C# code

    - by Espinas.iss
    I want to use in C# these methods: * int LibRaw::open_datastream(LibRaw_abstract_datastream *stream) * int LibRaw::open_file(const char *rawfile) * int LibRaw::open_buffer(void *buffer, size_t bufsize) * int LibRaw::unpack(void) * int LibRaw::unpack_thumb(void) that are stored in a libraw.dll. These functions one by one load data from file... I've been reading about P/Invoke but i'm not sure how to invoke them. Can anyone show me an example how to use all of these functions together in C# to load file (raw image stored in folder) or just how to PIvoke one of them. Thanx!

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  • Python shortcuts

    - by lyrae
    Python is filled with little neat shortcuts. For example: self.data = map(lambda x: list(x), data) and (although not so pretty) tuple(t[0] for t in self.result if t[0] != 'mysql' and t[0] != 'information_schema') among countless others. In the irc channel, they said "too many to know them all". I think we should list some here, as i love using these shortcuts to shorten & refctor my code. I'm sure this would benefit many.

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  • Dealing with &rest-parameters in common lisp

    - by Patrick
    I want define a functions that accepts &rest - parameters and delegates them to another function. (html "blah" "foo" baz) = "blahfoobaz" I did not find a better way than this one: (defun html (&rest values) (concatenate 'string "" (reduce #'(lambda(a b) (concatenate 'string a b)) values :initial-value "") "")) But this looks somewhat glumbsy to me, since line 4 does no more than concatenating the &rest parameter "values". I tried (concatenate 'string "" (values-list values) "") but this does not seem to work (SBCL). Could someone give me an advice? Kind regards

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