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• iphone singleton object synchronization

  - by user127091

  I'm working on an iphone app but this is probably a general question. I have a singleton Model class and there would be scenarios where multiple NSOperations (threads) would exist and work with the singleton object. If they all call the same method in this object, do i need to have some locking mechanism? Or can this method be executed only one at a time? I do not have a computer science background but my guess is that all threads would have their CALL to the same address (this method). Also can you please suggest a good beginner programming book that discusses general programming concepts. I don't have the brains for Knuth kinda books.

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• Generating code at compile-time using scripts

  - by Manux

  Hello, I would ideally like to be able to add (very repetitive) C/C++ code to my actual code, but at compile time, code which would come from say, the stdout of a python script, the same way one does with macros. For example, let's say I want to have functions that depend on the public attributes of a given class, being able to just write the following in my C++ code would be a blessing: generate_boring_functions(FooBarClass,"FooBarClass.cpp") Is that feasible using conventional means? Or must I hack with Makefiles and temporary source files? Thanks.

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• How to export user inputs (from python) to excel worksheet?

  - by mrn

  I am trying to develop a user form in python 2.7.3. Please note that I am a python beginner. I am trying to use xlwt to export data to excel. I want to write values of following variables i.e. a (value to write:'x1') & d (value to write: be user defined information in text box), a=StringVar() checkBox1=Checkbutton(root, text="text1", variable=a, onvalue="x1", offvalue="N/A") checkBox1.place(relx=0., rely=0., relwidth=0., relheight=0.) checkBox1.pack() d=StringVar() atextBox1=Entry(root, textvariable=d, font = '{MS Sans Serif} 10') atextBox1.pack() Need help badly. Thank you so much in advance

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• Projects to learn Python

  - by Andrew

  I know this isn't a question about a specific snippet of code or anything, but here goes - I've been messing around with the idea of learning Python since I'm pretty bored with PHP (and web development in general), but I can't think of any projects to help me learn. I've already worked through some of Project Euler with Python, but it's getting old. I know the basics, and I want to write something more fun that will introduce me to new things in Python. Is there a cliche beginner project for Python? (for example, PHP's would be a blog or something similiar) Are there any common Python projects for newcomers, or any uncommon ones that you'd suggest? Any ideas would help.

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• Is it still too early to hop aboard the Python 3 train?

  - by Znarkus

  I'm still a beginner to Python, so I thought I could as well learn the newest iteration of Python. Especially since it is now 3.1 or 3.2 something. But it seems like many mayor modules are still only supported by 2.6. Like the python-mysql module; from what I read on http://mysql-python.blogspot.com/ it seems like 3.x support won't be seen in any near future. Do you use version 3, how do you get around these problems? Should I retreat to 2.6? If not, what should I use to connect to MySQL?

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• Unresolved external symbol

  - by kriau

  I have two WIN32 DLL projects in the solution, main.dll should call a function in mgn.dll. mgn.dll has mgn.h header file: #ifdef MGN_EXPORTS #define MGN_API __declspec(dllexport) #else #define MGN_API __declspec(dllimport) #endif extern "C" bool MGN_API AttachMGN(void); and mgn.cpp source file: #include "stdafx.h" #include "mgn.h" MGN_API bool AttachMGN(void) { ... } main.dll calls AttachMGN function from one of the source file: #include "stdafx.h" #include "..\mgn\mgn.h" bool CreateClient() { return ::AttachMGN(); } mgn.dll compiles successfully. main.dll doesn't show any errors in VS text editor, I can navigate using "Go To Definition" function. However during build I get the error: error LNK2019: unresolved external symbol _imp_AttachMGN referenced in function "bool __cdecl CreateClient(void)" (?CreateClient@@AW4XZ) Both DLLs compile into the same folder. DependencyWalker shows the function AttachMGN as exported. Main project has a dependency set to Mgn project, if that matters. I believe that I simply have overlooked something.... Thanks in advance.

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• Visual C++ 9 Linker file size limitation.

  - by Raindog

  It appears that the visual C++ 9 linker has a file allocation algorithm that doubles the size of the file every allocation, so you get 512mb, 1024mb, 2048mb, 4096mb. The problem is that it is using a library that cannot handle files larger 2048MB, and as such crashes with an error such as "cannot read file at is the disk full or write protected". Is there a way to bypass this limitation or otherwise replace the linker with something else that works? A bit of background, I have a code generator that generates a large number of files, ~15k cpp files, I've managed to reduce the number of files to something about 6k to get something that at least completes the linking process, I would like to be able to include all 15k without having to create multiple libs.

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• C++ Virtual keyword as away to avoid including code units.

  - by user394663

  Currently we have a body of code that allows service plugins which offer forms of communication to the core e.g tcp/ip, udp/ip, usb, etc... These service plugins feedback notifier class instances to the core for further processing. In the current implementation a service project (which is a separate dynamically linked library brought in at runtime by the core via dlopen and friends) will compile against the notifier.cpp file that resides in the core source code (a separate project). This gives access to the notifiers method implementations. This works perfectly no complaints. Two alternative options: 1. put the notifier method implementations in the header file. 2. declare the notifier methods virtual and delay binding until runtime. Avoiding the issues of computational overhead what are the impacts of option 2? Are there any other options available to us? Thanks

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• CSV parser in C++

  - by User1

  All I need is a good CSV file parser for C++. At this point it can really just be a comma-delimited parser (ie don't worry about escaping new lines and commas). The main need is a line-by-line parser that will return a vector for the next line each time the method is called. I found this article which looks quite promising: http://www.boost.org/doc/libs/1_35_0/libs/spirit/example/fundamental/list_parser.cpp I've never used Boost's Spirit, but am willing to try it. Is it overkill/bloated or is it fast and efficient? Does anyone have faster algorithms using STL or anything else? Thanks!

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• automatically downloading and installing an exe file

  - by dbphydb

  I need to automate the process of downloading and installing an exe file abc.exe from say 'http://10.34.45.21:8080/cruisecontrol/artifacts/xxx_trunk_nightly_build/xxx/test/' I mean now i have to manually goto ''http://10.34.45.21:8080/cruisecontrol' then click on each folder before i finally click on the abc.exe file. Then it downloads the exe on my machine. Then i have to double click on the exe to install it. I want to automate this whole process such that when i run the script it will automatically download the exe file and install it. Is it possible to do this using php? I am very much a beginner. Any help will be of use.

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• C++ - Print Out Objects From Set

  - by John Smith

  If I have a C++ set, declaration set personList; with iterator, set::const_iterator location; how can I print out the contents of the set? They are all person objects, and I have overridden the operator<< for Person. The line that errors is: cout << location and it's in a basic for loop. Netbeans gives the following error: proj.cpp:78: error: no match for ‘operator<<’ in ‘std::cout << location’ so it looks like it wants an override for the iterator's <<. Basically, I am taking objects that used to be stored in an array format, but are now in a set. What is the equivalent to cout << array[i] for sets?

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• How Proxy server works with tcp/http connections?

  - by Vivek

  Since I am a beginner in the world of internet/networking, I always mess up with these kinds of doubts in my head while programming ;) .. My doubts are, While working behind a proxy, how my requests and responses work? Means my request headers and data will first reach to Proxy server- then proxy server sends it(same headers and data) to corresponding server. And server responses to it with a response header and body to the proxy server-then proxy server sends it to my computer. Wright? While using websockets we are upgrading our http connection to tcp. At this time what is happening @ Proxy server? Does the proxyserver also upgrades its connection to plain TCP? After opening such TCP connections, does the proxy server able to track/log those socket messsages? And most importantly, Is the proxy server transparent or acting like an original server infront of a client? Thanks for any answers or helpful links in advance.

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• c++ when to put method out side the class

  - by user63898

  i saw that some times in c++ applications using only namespace declarations with header and source file like this : #ifndef _UT_ #define _UT_ #include <string> #include <windows.h> namespace UT { void setRootPath(char* program_path, char* file_path); char * ConvertStringToCharP(std::string str); }; #endif //and then in UT.cpp #include "UT.h" namespace UT { char * ConvertStringToCharP(std::string str) { char * writable = new char[str.size() + 1]; std::copy(str.begin(), str.end(), writable); writable[str.size()] = '\0'; return writable; } void setRootPath(char* program_path, char* file_path) { //... } } is it better then defining classic class with static methods? or just simple class ? dose this method has something better for the compiler linker ? the methods in this namespace are called allot of times .

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• Many-to-one relationship in SQLAlchemy

  - by Arrieta

  This is a beginner-level question. I have a catalog of mtypes: mtype_id name 1 'mtype1' 2 'mtype2' [etc] and a catalog of Objects, which must have an associated mtype: obj_id mtype_id name 1 1 'obj1' 2 1 'obj2' 3 2 'obj3' [etc] I am trying to do this in SQLAlchemy by creating the following schemas: mtypes_table = Table('mtypes', metadata, Column('mtype_id', Integer, primary_key=True), Column('name', String(50), nullable=False, unique=True), ) objs_table = Table('objects', metadata, Column('obj_id', Integer, primary_key=True), Column('mtype_id', None, ForeignKey('mtypes.mtype_id')), Column('name', String(50), nullable=False, unique=True), ) mapper(MType, mtypes_table) mapper(MyObject, objs_table, properties={'mtype':Relationship(MType, backref='objs', cascade="all, delete-orphan")} ) When I try to add a simple element like: mtype1 = MType('mtype1') obj1 = MyObject('obj1') obj1.mtype=mtype1 session.add(obj1) I get the error: AttributeError: 'NoneType' object has no attribute 'cascade_iterator' Any ideas?

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• Vista Basic theme ribbon issue

  - by Alain Rist

  Under Vista, when in Basic theme, after calling IUIFramework::Destroy() the Vista theme is lost, and enlarging the window does not display outside of the initial area. You can repro it easily with the SimpleRibbon SDK sample. In simpleribbon.cpp, insert in the WndProc switch block: case WM_KEYUP: DestroyFramework(); InvalidateRect(hWnd, NULL, TRUE); break; Compile, run, hit a key and try to enlarge in Vista Basic Theme (no problem in Win7 or Vista aero or Windows classic). How to work around? cheers, AR

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• Does any method exist quickly to detect valid range versions of used library

  - by daneel-yaitskov

  I'm a beginner Haskell programmer. I have written some useful code for the last six month. And I want to release a library from it. The code will use system installation cabal as any Haskell library. A library is released with cabal has a meta data file where there is a logical predicate from the libraries and their versions. A developer usually uses one set libraries. It tediously care a set of the sets libraries. How to know either my library is compiled successfully or not for some subset libraries?

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• how to create resources without VS C++ 2008 creating MFC files

  - by numerical25

  I am creating a WIN32 application and I want most of all my application events to be made through the message queue. But everytime I create a dialog box or any resource like that. The IDE auto generates code that I don't necessarily need. I believe it's MFC code not sure. here it is. // dlgChangeDevice.cpp : implementation file // #include "stdafx.h" #include "ZFXD3D.h" #include "dlgChangeDevice.h" // dlgChangeDevice dialog IMPLEMENT_DYNAMIC(dlgChangeDevice, CDialog) dlgChangeDevice::dlgChangeDevice(CWnd* pParent /*=NULL*/) : CDialog(dlgChangeDevice::IDD, pParent) { } dlgChangeDevice::~dlgChangeDevice() { } void dlgChangeDevice::DoDataExchange(CDataExchange* pDX) { CDialog::DoDataExchange(pDX); } BEGIN_MESSAGE_MAP(dlgChangeDevice, CDialog) ON_CBN_SELCHANGE(IDC_COMBO5, &dlgChangeDevice::OnCbnSelchangeCombo5) END_MESSAGE_MAP() // dlgChangeDevice message handlers void dlgChangeDevice::OnCbnSelchangeCombo5() { // TODO: Add your control notification handler code here } Not sure what it is but I don't need it. I want to retrieve all my code through the dialog message queue. So what should I do ?? Just disregard it and delete it. Will a hurt anything by doing so ??

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• Question about inserting assembly code in C++

  - by Bruce

  I am working on VC++ compiler. I want to accomplish the following The variables s.AddrFrame.Offset and s.AddrStack.Offset contain the value of EBP and ESP respectively. I want to extract the value of old EBP and the return address. Assuming the address EBP + 1 contains the old 32 bit EBP value and EBP + 5 the return address I wrote the following code: unsigned int old_ebp = 0; unsigned int ret_addr = 0; __asm{ mov old_ebp, DWORD PTR [s.AddrFrame.Offset + 1] mov ret_addr, DWORD PTR [s.AddrStack.Offset + 5] } But this is not compiling xxxx.cpp(1130) : error C2415: improper operand type Please Help

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• Converting a C# code to F#??

  - by Brendon

  Hello all I am just a beginner in programing i wish covert some code from C# to F#, I have encotered this code: float[] v1=new float[10]; ... //Enqueue the Execute command. Queue.Execute(kernelVecSum, null, **new long[] { v1.Length }**, null, null); I have previously ask how to convert the v1 object, I think i know how, But how do i use the function call especially the "new long[] { v1.Length }" part of the function argument, what does "new long[] { v1.Length }" mean?? I have created v1 like this "let v1 = [| for i in 1.0 .. 10.0 -> 2.0 * i |]" Is it correct?? or should i use v1 like this "let v1 = ref [| for i in 1.0 .. 10.0 -> 2.0 * i |]" ???

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• After getting the 'It worked!' page with Djangoappengine, what do I do next?

  - by Jacques Bosch

  I followed the Djangoappengine instructions. I used their django-testapp and copied the following folders in the django-testapp folder according to what I understood the instructions to say: django djangoappengine djangotoolbox I then started the dev server by running: manage.py runserver Then navigated to http://localhost:8000/ and got the "It worked!" page, which is great, but it says the following at the bottom: You're seeing this message because you have DEBUG = True in your Django settings file and you haven't configured any URLs. Get to work! I am an absolute beginner with Django and App Engine and Djangoappengine and Django-nonrel, so I am pretty lost. How do I configure URLs? Or a link to the how to will help. I took a look at the Django tutorial, but am unsure how much of it is relevant to Djangoappengine and Django-nonrel as a lot of the starting steps have to do with SQL databases. Basically some direction on how to get my app running will be great. Thanx much.

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• Jquery/CSS help needed to make fallback for IE and older browsers

  - by matt_50

  Wondering if any of you can help me: I've made a signup modal that uses a CSS transform to switch between two methods of signing up. I've decided to try a 'card flip' type effect. Have a look at this JSfiddle in any browser that supports CSS 3D transforms - click the 'old fashioned way' text to 'flip' the modal (simplified for demo purposes): http://jsfiddle.net/voodoo6/cnTMz/8/ Then take a look in IE8/9 - as the 'back' is taller than the front and IE does;t support 'backface-visibility: hidden;' the reverse can be seen below the front. I've been trying to use JQuery and conditional CSS to 'display:none' the 'back' on load in IE (and older browsers), then add a 'display:block;' class to show it on click, problem is, I'm a JQuery beginner and have been struggling to get it to work! Not even sure if this is the best approach? Can anybody suggest an approach that would get this working in less-capable browsers? Thanks for any advice..

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• Is It Worth Using Bitwise Operators In Methods?

  - by user1626141

  I am very new to Java (and programming in general, my previous experience is with ActionScript 2.0 and some simple JavaScript), and I am working my way slowly and methodically through Java: A Beginner's Guide by Herbert Schildt. It is an incredible book. For one thing, I finally understand more-or-less what bitwise operators (which I first encountered in ActionScript 2.0) do, and that they are more efficient than other methods for certain sums. My question is, is it more efficient to use a method that uses, say, a shift right, to perform all your divisions/2 (or divisions/even) for you in a large program with many calculations (in this case, a sprawling RPG), or is it more efficient to simply use standard mathematical operations because the compiler will optimise it all for you? Or, am I asking the wrong question entirely?

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• Build config file into executable?

  - by REM

  I am currently working on a little graphics demo (using DirectX) which is primarily based around an HLSL shader I am working on. Using the D3DX10CreateEffectFromFile I am loading (and compiling the shader) at runtime as I find it easier for tweaking. However, once I am done I'd like to do some combination of the following: Pre-compile the shader so the demo starts up faster for the user Bury (compile into the executable) the compiled shader (or maybe just the source if necessary) Primarily, I want to do this because I want the demo to just be one file that can be very easily copied around. One thing I could easily do is just put the source text right into a cpp but that would be very tedious I needed to update it later. Is it possible to do something like this (using Visual Studio, DirectX, HLSL)?

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• Writing to CSV issue in Spyder

  - by 0003

  I am doing the Kaggle Titanic beginner contest. I generally work in Spyder IDE, but I came across a weird issue. The expected output is supposed to be 418 rows. When I run the script from terminal the output I get is 418 rows (as expected). When I run it in Spyder IDE the output is 408 rows not 418. When I re-run it in the current python process, it outputs the expected 418 rows. I posted a redacted portion of the code that has all of the relevant bits. Any ideas? import csv import numpy as np csvFile = open("/train.csv","ra") csvFile = csv.reader(csvFile) header = csvFile.next() testFile = open("/test.csv","ra") testFile = csv.reader(testFile) testHeader = testFile.next() writeFile = open("/gendermodelDebug.csv", "wb") writeFile = csv.writer(writeFile) count = 0 for row in testFile: if row[3] == 'male': do something to row writeFile.writerow(row) count += 1 elif row[3] == 'female': do something to row writeFile.writerow(row) count += 1 else: raise ValueError("Did not find a male or female in %s" % row)

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• Delay-Load equivalent in unix based systems

  - by saran

  What is the delay load equivalent in unix based system. I have a code foo.cpp, While compiling with gcc I link it to shared objects(totally three .so files are there.).Each of the .so file for different option. ./foo -v needs libversion.so ./foo -update needs libupdate.so I need the symbol for those libraries should be resolved only at the run time. ./foo -v should not break even if libupdate.so library is not there. It is working in windows using the delay load option(in properties of dll). What is its equivalent in unix systems. Will '-lazy' option does the same in UNIX?. If so,Where to include this option? (in makefile or with linker ld). I am not good in unix. Please help me.. Thanks in advance.

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