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  • Design Philosophy Question - When to create new functions

    - by Eclyps19
    This is a general design question not relating to any language. I'm a bit torn between going for minimum code or optimum organization. I'll use my current project as an example. I have a bunch of tabs on a form that perform different functions. Lets say Tab 1 reads in a file with a specific layout, tab 2 exports a file to a specific location, etc. The problem I'm running into now is that I need these tabs to do something slightly different based on the contents of a variable. If it contains a 1 I may need to use Layout A and perform some extra concatenation, if it contains a 2 I may need to use Layout B and do no concatenation but add two integer fields, etc. There could be 10+ codes that I will be looking at. Is it more preferable to create an individual path for each code early on, or attempt to create a single path that branches out only when absolutely required. Creating an individual path for each code would allow my code to be extremely easy to follow at a glance, which in turn will help me out later on down the road when debugging or making changes. The downside to this is that I will increase the amount of code written by calling some of the same functions in multiple places (for example, steps 3, 5, and 9 for every single code may be exactly the same. Creating a single path that would branch out only when required will be a bit messier and more difficult to follow at a glance, but I would create less code by placing conditionals only at steps that are unique. I realize that this may be a case-by-case decision, but in general, if you were handed a previously built program to work on, which would you prefer?

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  • C two functions in one with casts

    - by Favolas
    I have two functions that do the exact same thing but in two different types of struct and this two types of struct are very similar. Imagine I have this two structs. typedef struct nodeOne{ Date *date; struct nodeOne *next; struct nodeOne *prev; }NodeOne; typedef struct nodeTwo{ Date *date; struct nodeTwo *next; struct nodeTwo *prev; }NodeTwo; Since my function to destroy each of the list is almost the same (Just the type of the arguments are different) I would like to make just one function to make the two thins. I have this two functions void destroyListOne(NodeOne **head, NodeOne **tail){ NodeOne *aux; while (*head != NULL){ aux = *head; *head = (*head)->next; free(aux); } *tail = NULL; } and this one: void destroyListTwo(NodeTwo **head, NodeTwo **tail){ NodeTwo *aux; while (*head != NULL){ aux = *head; *head = (*head)->next; free(aux); } *tail = NULL; } Since they are very similar I thought making something like this: void destroyList(void **ini, void **end, int listType){ if (listType == 0) { NodeOne *aux; NodeOne head = (NodeOne) ini; NodeOne tail = (NodeOne) ed; } else { NodeTwo *aux; NodeTwo head = (NodeTwo) ini; NodeTwo tail = (NodeTwo) ed; } while (*head != NULL){ aux = *head; *head = (*head)->next; free(aux); } *tail = NULL; } As you may now this is not working but I want to know if this is possible to achieve. I must maintain both of the structs as they are.

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  • summing functions handles in matlab

    - by user552231
    Hi I am trying to sum two function handles, but it doesn't work. for example: y1=@(x)(x*x); y2=@(x)(x*x+3*x); y3=y1+y2 The error I receive is "??? Undefined function or method 'plus' for input arguments of type 'function_handle'." This is just a small example, in reality I actually need to iteratively sum about 500 functions that are dependent on each other. EDIT The solution by Clement J. indeed works but I couldn't manage to generalize this into a loop and ran into a problem. I have the function s=@(x,y,z)((1-exp(-x*y)-z)*exp(-x*y)); And I have a vector v that contains 536 data points and another vector w that also contains 536 data points. My goal is to sum up s(v(i),y,w(i)) for i=1...536 Thus getting one function in the variable y which is the sum of 536 functions. The syntax I tried in order to do this is: sum=@(y)(s(v(1),y,z2(1))); for i=2:536 sum=@(y)(sum+s(v(i),y,z2(i))) end

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  • Matlab GUI: How to Save the Results of Functions (states of application)

    - by niko
    Hi, I would like to create an animation which enables the user to go backward and forward through the steps of simulation. An animation has to simulate the iterative process of channel decoding (a receiver receives a block of bits, performs an operation and then checks if the block corresponds to parity rules. If the block doesn't correspond the operation is performed again and the process finally ends when the code corresponds to a given rules). I have written the functions which perform the decoding process and return a m x n x i matrix where m x n is the block of data and i is the iteration index. So if it takes 3 iterations to decode the data the function returns a m x n x 3 matrix with each step is stired. In the GUI (.fig file) I put a "decode" button which runs the method for decoding and there are buttons "back" and "forward" which have to enable the user to switch between the data of recorded steps. I have stored the "decodedData" matrix and currentStep value as a global variable so by clicking "forward" and "next" buttons the indices have to change and point to appropriate step states. When I tried to debug the application the method returned the decoded data but when I tried to click "back" and "next" the decoded data appeared not to be declared. Does anyone know how is it possible to access (or store) the results of the functions in order to enable the described logic which I want to implement in Matlab GUI?

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  • jQuery plugin Private functions inside Vs. Outside the each loop

    - by Pablo
    What is the difference between including private functions in a jQuery plugin in the examples below: Outside the loop: (function( $ ){ var defaults = {}; $.fn.cmFlex = function(opts) { this.each(function() { var $this = $(this); //Element specific options var o = $.extend({}, defaults, opts); //Code here }); function f1(){.... function f3(){.... function f2(){.... }; })( jQuery ); Inside the loop: (function( $ ){ var defaults = {}; $.fn.cmFlex = function(opts) { this.each(function() { var $this = $(this); //Element specific options var o = $.extend({}, defaults, opts); function f1(){.... function f3(){.... function f2(){.... }); }; })( jQuery ); The advantage of including the functions in the loop is that i will be able to access the $this variable as well as the Element specific options from f1() f2() f3(), are there any disadvantages to this?

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  • Importing a C DLL's functions into a C++ program

    - by bobobobo
    I have a 3rd party library that's written in C. It exports all of its functions to a DLL. I have the .h file, and I'm trying to load the DLL from my C++ program. The first thing I tried was surrounding the parts where I #include the 3rd party lib in #ifdef __cplusplus extern "C" { #endif and, at the end #ifdef __cplusplus } // extern "C" #endif But the problem there was, all of the DLL file function linkage looked like this in their header files: a_function = (void *)GetProcAddress(dll, "a_function"); While really a_function had type int (*a_function) (int *). Apparently MSVC++ compiler doesn't like this, while MSVC compiler does not seem to mind. So I went through (brutal torture) and fixed them all to the pattern typedef int (*_a_function) (int *); _a_function a_function ; Then, to link it to the DLL code, in main(): a_function = (_a_function)GetProcAddress(dll, "a_function"); This SEEMS to make the compiler MUCH, MUCH happier, but it STILL complains with this final set of 143 errors, each saying for each of the DLL link attempts: error LNK2005: _a_function already defined in main.obj main.obj Multiple symbol definition errors.. sounds like a job for extern! SO I went and made ALL the function pointer declarations as follows: function_pointers.h typedef int (*_a_function) (int *); extern _a_function a_function ; And in a cpp file: function_pointers.cpp #include "function_pointers.h" _a_function a_function ; ALL fine and dandy.. except for linker errors now of the form: error LNK2001: unresolved external symbol _a_function main.obj Main.cpp includes "function_pointers.h", so it should know where to find each of the functions.. I am bamboozled. Does any one have any pointers to get me functional? (Pardon the pun..)

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  • Socket send recv functions

    - by viswanathan
    I have created a socket using the following lines of code. Now i change the value of the socket i get like this m_Socket++; Even now the send recv socket functions succeeds without throwing SOCKET_ERROR. I expect that it must throw error. Am i doing something wrong. struct sockaddr_in ServerSock; // Socket address structure to bind the Port Number to listen to char *localIP ; SOCKET SocServer; //To Set up the sockaddr structure ServerSock.sin_family = AF_INET; ServerSock.sin_addr.s_addr = INADDR_ANY; ServerSock.sin_port = htons(pLantronics->m_wRIPortNo); // To Create a socket for listening on wPortNumber if(( SocServer = socket( AF_INET, SOCK_STREAM, 0 )) == INVALID_SOCKET ) { return FALSE; } //To bind the socket with wPortNumber if(bind(SocServer,(sockaddr*)&ServerSock,sizeof(ServerSock))!=0) { return FALSE; } // To Listen for the connection on wPortNumber if(listen(SocServer,SOMAXCONN)!=0) { return FALSE; } // Structure to get the IP Address of the connecting Entity sockaddr_in insock; int insocklen=sizeof(insock); //To accept the Incoming connection on the wPortNumber pLantronics->m_Socket=accept(SocServer,(struct sockaddr*)&insock,&insocklen); if(pLantronics->m_Socket == INVALID_SOCKET) { shutdown(SocServer, 2 ); closesocket(SocServer ); return FALSE; } // To make socket non-blocking DWORD dwNonBlocking = 1; if(ioctlsocket( pLantronics->m_Socket, FIONBIO, &dwNonBlocking )) { shutdown(pLantronics->m_Socket, 2); closesocket(pLantronics->m_Socket); return FALSE; } pLantronics->m_sModemName = inet_ntoa(insock.sin_addr); Now i do m_Socket++;//change to some other number ideally expecting send recv to fail. Even now the send recv socket functions succeeds without throwing SOCKET_ERROR. I expect that it must throw error. Am i doing something wrong.

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  • Access to and availability of private member functions in C++

    - by David
    I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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  • Referenced vector does not pass through functions

    - by kylepayne
    The referenced vector to functions does not hold the information in memory. Do I have to use pointers? Thanks. #include <iostream> #include <cstdlib> #include <vector> #include <string> using namespace std; void menu(); void addvector(vector<string>& vec); void subvector(vector<string>& vec); void vectorsize(const vector<string>& vec); void printvec(const vector<string>& vec); void printvec_bw(const vector<string>& vec); int main() { vector<string> svector; menu(); return 0; } //functions definitions void menu() { vector<string> svector; int choice = 0; cout << "Thanks for using this program! \n" << "Enter 1 to add a string to the vector \n" << "Enter 2 to remove the last string from the vector \n" << "Enter 3 to print the vector size \n" << "Enter 4 to print the contents of the vector \n" << "Enter 5 ----------------------------------- backwards \n" << "Enter 6 to end the program \n"; cin >> choice; switch(choice) { case 1: addvector(svector); menu(); break; case 2: subvector(svector); menu(); break; case 3: vectorsize(svector); menu(); break; case 4: printvec(svector); menu(); break; case 5: printvec_bw(svector); menu(); break; case 6: exit(1); default: cout << "not a valid choice \n"; // menu is structured so that all other functions are called from it. } } void addvector(vector<string>& vec) { //string line; //int i = 0; //cin.ignore(1, '\n'); //cout << "Enter the string please \n"; //getline(cin, line); vec.push_back("the police man's beard is half-constructed"); } void subvector(vector<string>& vec) { vec.pop_back(); return; } void vectorsize(const vector<string>& vec) { if (vec.empty()) { cout << "vector is empty"; } else { cout << vec.size() << endl; } return; } void printvec(const vector<string>& vec) { for(int i = 0; i < vec.size(); i++) { cout << vec[i] << endl; } return; } void printvec_bw(const vector<string>& vec) { for(int i = vec.size(); i > 0; i--) { cout << vec[i] << endl; } return; }

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  • Table valued function only returns CLR error

    - by Anthony
    I have read-only access to a database that was set up for a third-party, closed-source app. Once group of (hopefully) useful table functions only returns the error: Failed to initialize the Common Language Runtime (CLR) v2.0.50727 with HRESULT 0x80131522. You need to restart SQL server to use CLR integration features. (severity 16) But in theory, the third-party app should be able to use the function (either directly or indirectly), so I'm convinced I'm not setting things up right. I'm very new to SQL Server, so I could be missing something obvious. Or I could be missing something really slight, I have no idea. Here is an example of a query that returns the above error: SELECT * FROM dbo.UncompressDataDateRange(4,'Apr 24 2010 12:00AM','Apr 30 2010 12:00AM') Where the function takes three parameters: The Data Set (int) -- basically the data has 6 classifications, and the giant table this should be pulling from has a column to indicate which is which. startDate (smalldatetime) endDate (smalldatetime) There are other, similar functions that expand on the same idea, all returning the same error. Quick Note: I'm not sure if this is relevant, but I was able to connect to the database via SQL Studio (but without the privs to script the functions as code), and a checked the dependency for the above sample function. It turns out that it is a dependent of a view that I have gotten to work, and that view is dependent of the larger, much-hairier data-table. This makes me think I should somehow be pointing the function at the results of the view, but I'm not seeing any documentation that shows how that is done.

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  • How to create Automation Add In Formula/Function and Excel Add In buttons (vsto) for them together?

    - by ticky
    Ok, let me explain it little bit better. Here is one example how to create formula/functions http://blogs.msdn.com/b/eric_carter/archive/2004/12/01/273127.aspx?PageIndex=1#comments I implemented something like that, I even added values in registry, so that this Automation AddIn doesn't have to be added manually in Excel, but automatically.. I created SETUP project for this project and it works GREAT. Then.. After some time, I wanted to create buttons in Excel for functions that I use. Those are custom functions, using some web services. I created Excel AddIn and added Ribbon with buttons - one button = one custom function. I can publish this project and I am creating VSTO, so this way, I can install excel ribbon buttons in custom group of mine. Now, I have 2 installations, first for Automation AddIn and second for Excel AddIn. How can I connect them? I tried to include VSTO to Setup - something like this: [I WILL ADD IT LATER] When I install it, it works great, it installs both parts. But when I install on my friends computer, it doesn't shows Ribbon buttons. What could be the problem? If there is some other way to integrate those two, I would be very grateful!!!!! Thanks! Tijana

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  • Importing matlab functions in matlab

    - by Krt_Malta
    Hi, I have some Matlab functions defined in .m files and I'd like to import them into Matlab (as in I'd like them to form part of the commands). Is this possible please and how can I do this? Thank you very much and regards, Krt_Malta

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  • List stored functions using a table in PostgreSQL

    - by Paolo B.
    Just a quick and simple question: in PostgreSQL, how do you list the names of all stored functions/stored procedures using a table using just a SELECT statement, if possible? If a simple SELECT is insufficient, I can make do with a stored function. My question, I think, is somewhat similar to this other question, but this other question is for SQL Server 2005: http://stackoverflow.com/questions/119679/list-of-stored-procedure-from-table (optional) For that matter, how do you also list the triggers and constraints that use the same table in the same manner?

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  • Loading, listing, and using R Modules and Functions in PL/R

    - by Dave Jarvis
    I am having difficulty with: Listing the R packages and functions available to PostgreSQL. Installing a package (such as Kendall) for use with PL/R Calling an R function within PostgreSQL Listing Available R Packages Q.1. How do you find out what R modules have been loaded? SELECT * FROM r_typenames(); That shows the types that are available, but what about checking if Kendall( X, Y ) is loaded? For example, the documentation shows: CREATE TABLE plr_modules ( modseq int4, modsrc text ); That seems to allow inserting records to dictate that Kendall is to be loaded, but the following code doesn't explain, syntactically, how to ensure that it gets loaded: INSERT INTO plr_modules VALUES (0, 'pg.test.module.load <-function(msg) {print(msg)}'); Q.2. What would the above line look like if you were trying to load Kendall? Q.3. Is it applicable? Installing R Packages Using the "synaptic" package manager the following packages have been installed: r-base r-base-core r-base-dev r-base-html r-base-latex r-cran-acepack r-cran-boot r-cran-car r-cran-chron r-cran-cluster r-cran-codetools r-cran-design r-cran-foreign r-cran-hmisc r-cran-kernsmooth r-cran-lattice r-cran-matrix r-cran-mgcv r-cran-nlme r-cran-quadprog r-cran-robustbase r-cran-rpart r-cran-survival r-cran-vr r-recommended Q.4. How do I know if Kendall is in there? Q.5. If it isn't, how do I find out what package it is in? Q.6. If it isn't in a package suitable for installing with apt-get (aptitude, synaptic, dpkg, what have you), how do I go about installing it on Ubuntu? Q.7. Where are the installation steps documented? Calling R Functions I have the following code: EXECUTE 'SELECT ' 'regr_slope( amount, year_taken ),' 'regr_intercept( amount, year_taken ),' 'corr( amount, year_taken ),' 'sum( measurements ) AS total_measurements ' 'FROM temp_regression' INTO STRICT slope, intercept, correlation, total_measurements; This code calls the PostgreSQL function corr to calculate Pearson's correlation over the data. Ideally, I'd like to do the following (by switching corr for plr_kendall): EXECUTE 'SELECT ' 'regr_slope( amount, year_taken ),' 'regr_intercept( amount, year_taken ),' 'plr_kendall( amount, year_taken ),' 'sum( measurements ) AS total_measurements ' 'FROM temp_regression' INTO STRICT slope, intercept, correlation, total_measurements; Q.8. Do I have to write plr_kendall myself? Q.9. Where can I find a simple example that walks through: Loading an R module into PG. Writing a PG wrapper for the desired R function. Calling the PG wrapper from a SELECT. For example, would the last two steps look like: create or replace function plr_kendall( _float8, _float8 ) returns float as ' agg_kendall(arg1, arg2) ' language 'plr'; CREATE AGGREGATE agg_kendall ( sfunc = plr_array_accum, basetype = float8, -- ??? stype = _float8, -- ??? finalfunc = plr_kendall ); And then the SELECT as above? Thank you!

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  • How are hash functions like MD5 unique?

    - by Aly
    Im aware that MD5 has had some collisions but this is more of a high level question about hashing functions. If MD5 hashes any arbitrary string into a 32-digit hex value, then according to the Pigeonhole Principle surely this can not be unique as there are more unique arbitrary strings than there are unique 32-digit hex values

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  • OSX/Darwin unresolved symbols when linking functions from <math.h>

    - by tbone
    I'm in the process of porting a large'ish (~1M LOC) project from a Window/Visual Studio environment to other platforms, the first of which happens to be Mac OS X. Originally the project was configured as Visual Studio solutions and projects, but now I'm using (the excellent) Premake (http://industriousone.com/premake) to generate project files for multiple platforms (VS, XCode, GMake). I configured, ported and built the first few projects without any significant problems, but having ported the math lib, I ran into this weird linking error that I haven't been able to resolve: Any functions used from math.h will fail to link (causing unresolved symbols). For reference, I'm using Premake v4.2.1 to generate projects for XCode v3.2.1, which is building using gcc v4.2 for the x86_64 architecture. (All this on 64-bit Snow Leopard) I've tried to persuade gcc to link and build everything against a 'known' SDK by adding -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.6 to the build command line. Now under normal circumstances, adding -lm should take care of this, however in Darwin, those math libs are included in libSystem, which, as far as I can tell, gets implicitly linked by gcc/ld. I've tried creating a dummy project from within XCode which just runs: float f = log2(2.0)+log2f(3.f)+log1p(1.1)+log1pf(1.2f)+sin(8.0); std::cout << f << std::endl; and as expected, this builds just fine. However, if I put the same thing in the code inside the Premake generated project, all those math functions end up unresolved. Now comparing the linking command from the 'native' XCode project with my generated XCode project, they seem pretty identical (except that my generated project links other libs as well). 'Native' project: /Developer/usr/bin/g++-4.2 -arch x86_64 -dynamiclib -isysroot /Developer/SDKs/MacOSX10.6.sdk -Lsomepath -Fsomepath -filelist somefile -install_name somename -mmacosx-version-min=10.6 -single_module -compatibility_version 1 -current_version 1 -o somename Generated project: /Developer/usr/bin/g++-4.2 -arch x86_64 -dynamiclib -Lsomepath -Fsomepath -filelist somefile -install_name somename -isysroot /Developer/SDKs/MacOSX10.6.sdk -mmacosx-version-min=10.6 somelib.a somelib2.a somelib.dylib somelib2.dylib -single_module -compatibility_version 1 -current_version 1 -o somename Any help or hints about how to proceed would be most appreciated. Are there any gcc flags or other tools that can help me resolve this?

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  • Casting functions -- Is it a code smell?

    - by Earlz
    I recently began to start using functions to make casting easier on my fingers for one instance I had something like this ((Dictionary<string,string>)value).Add(foo); and converted it to a tiny little helper function so I can do this ToDictionary(value).Add(foo); Is this a code smell? (also I've marked this language agnostic even though my example is C#)

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  • Problem with upper-case and lower-case xpath functions in selenium IDE

    - by Aristotelis
    Hi, I am trying to get a xpath query using the xpath function lower-case or uppper-case, but they seem to not work in selenium (where I test my xpath before I apply it). Example that does NOT work: //*[.=upper-case('some text')] I have no problem locating the nodes I need in complex path and even using aggregated functions, as long as I don't use the upper and lower case. Has anyone encountered this before? Does it make sense? Thanks.

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