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  • Pass variable name to a function in r

    - by Misha
    Is it possible to pass just a variable name in a function call and have it utilised as such within the function?? pseudocode: q<-function(A){ b<-(w%in%A.2|w%in%A.7) factor(b,levels=c(F,T),labels=c("non-"A,A))} w<-c(0:10) e.2<-c(1,2) e.7<-c(6,7) what I´d like to do is q(e) and have returned non-e,e,e,non-e,non-e,e,e,non-e,non-e //M q<-function(A) { a2<-get(paste(a,".2",sep="")) a7<-get(paste(a,".7",sep="")) b<-(w%in%a2|%in%a7) factor(b,levels=c(F,T),labels=c(paste("non-",a,sep=""),a)) } q("e") Thx, M

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  • Passing a pointer to a function that doesn't match the requirements of the formal parameter

    - by Andreas Grech
    int valid (int x, int y) { return x + y; } int invalid (int x) { return x; } int func (int *f (int, int), int x, int y) { //f is a pointer to a function taking 2 ints and returning an int return f(x, y); } int main () { int val = func(valid, 1, 2), inval = func(invalid, 1, 2); // <- 'invalid' does not match the contract printf("Valid: %d\n", val); printf("Invalid: %d\n", inval); /* Output: * Valid: 3 * Invalid: 1 */ } At the line inval = func(invalid, 1, 2);, why am I not getting a compiler error? If func expects a pointer to a function taking 2 ints and I pass a pointer to a function that takes a single int, why isn't the compiler complaining? Also, since this is happening, what happens to the second parameter y in the invalid function?

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  • Function name inside a variable

    - by John Doe
    Hello. I have a simple question (i guess). I'm getting the name of the function inside a variable from database. After that, i want to run the specific function. How can i echo the function's name inside the php file? The code is something like this: $variable= get_specific_option; //execute function $variable_somesuffix(); The "somesuffix" will be a simple text. I tried all the things i had in mind but nothing worked.

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  • removing dependancy of a private function inside a public function using Rhino Mocks

    - by L G
    Hi All, I am new to mocking, and have started with Rhino Mocks. My scenario is like this..in my class library i have a public function and inside it i have a private function call, which gets output from a service.I want to remove the private function dependency. public class Employee { public virtual string GetFullName(string firstName, string lastName) { string middleName = GetMiddleName(); return string.Format("{0} {2} {1}", firstName, lastName,middleName ); } private virtual string GetMiddleName() { // Some call to Service return "George"; } } This is not my real scenario though, i just wanted to know how to remove dependency of GetMiddleName() function and i need to return some default value while unit testing. Note : I won't be able to change the private function here..or include Interface..Keeping the functions as such, is there any way to mock this.Thank

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  • How to pass function reference into arguments

    - by Ockonal
    Hi, I'm using boost::function for making function-references: typedef boost::function<void (SomeClass &handle)> Ref; someFunc(Ref &pointer) {/*...*/} void Foo(SomeClass &handle) {/*...*/} What is the best way to pass Foo into the someFunc? I tried something like: someFunc(Ref(Foo));

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  • How to catch unintentional function interpositioning?

    - by SiegeX
    Reading through my book Expert C Programming, I came across the chapter on function interpositioning and how it can lead to some serious hard to find bugs if done unintentionally. The example given in the book is the following: my_source.c mktemp() { ... } main() { mktemp(); getwd(); } libc mktemp(){ ... } getwd(){ ...; mktemp(); ... } According to the book, what happens in main() is that mktemp() (a standard C library function) is interposed by the implementation in my_source.c. Although having main() call my implementation of mktemp() is intended behavior, having getwd() (another C library function) also call my implementation of mktemp() is not. Apparently, this example was a real life bug that existed in SunOS 4.0.3's version of lpr. The book goes on to explain the fix was to add the keyword static to the definition of mktemp() in my_source.c; although changing the name altogether should have fixed this problem as well. This chapter leaves me with some unresolved questions that I hope you guys could answer: Does GCC have a way to warn about function interposition? We certainly don't ever intend on this happening and I'd like to know about it if it does. Should our software group adopt the practice of putting the keyword static in front of all functions that we don't want to be exposed? Can interposition happen with functions introduced by static libraries? Thanks for the help. EDIT I should note that my question is not just aimed at interposing over standard C library functions, but also functions contained in other libraries, perhaps 3rd party, perhaps ones created in-house. Essentially, I want to catch any instance of interpositioning regardless of where the interposed function resides.

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  • Constructing a function call in C

    - by 0x6adb015
    Given that I have a pointer to a function (provided by dlsym() for example) and a linked list of typed arguments, how can I construct a C function call with those arguments? Example: struct param { enum type { INT32, INT64, STRING, BOOL } type; union { int i32; long long i64; char *str; bool b; } value; struct param *next; }; int call_this(int (*function)(), struct param *args) { int result; /* magic here that calls function(), which has a prototype of f(int, long long, char *, bool); , when args consist of a linked list of INT32, INT64, STRING, BOOL types. */ return result; } The OS is Linux. I would like the solution to be portable across MIPS, PPC and x86 (all 32 bits) architecture, using GCC as the compiler. Thanks!

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  • Syncronizing indices of function pointer table to table contents

    - by Thomas Matthews
    In the embedded system I'm working on, we are using a table of function pointers to support proprietary Dynamic Libraries. We have a header file that uses named constants (#define) for the function pointer indices. These values are used in calculating the location in the table of the function's address. Example: *(export_table.c)* // Assume each function in the table has an associated declaration typedef void (*Function_Ptr)(void); Function_Ptr Export_Function_Table[] = { 0, Print, Read, Write, Process, }; Here is the header file: *export_table.h* #define ID_PRINT_FUNCTION 1 #define ID_READ_FUNCTION 2 #define ID_WRITE_FUNCTION 3 #define ID_PROCESS_FUNCTION 4 I'm looking for a scheme to define the named constants in terms of their location in the array so that when the order of the functions changes, the constants will also change. (Also, I would like the compiler or preprocessor to calculate the indices to avoid human mistakes like typeo's.)

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  • Hashing a python function to regenerate output when the function is modified

    - by Seth Johnson
    I have a python function that has a deterministic result. It takes a long time to run and generates a large output: def time_consuming_function(): # lots_of_computing_time to come up with the_result return the_result I modify time_consuming_function from time to time, but I would like to avoid having it run again while it's unchanged. [time_consuming_function only depends on functions that are immutable for the purposes considered here; i.e. it might have functions from Python libraries but not from other pieces of my code that I'd change.] The solution that suggests itself to me is to cache the output and also cache some "hash" of the function. If the hash changes, the function will have been modified, and we have to re-generate the output. Is this possible or ridiculous? Updated: based on the answers, it looks like what I want to do is to "memoize" time_consuming_function, except instead of (or in addition to) arguments passed into an invariant function, I want to account for a function that itself will change.

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  • How to store a function in a member of class? (Using function as callback)

    - by Dane
    I want to store a function as a class member and call it inside the class? Pretty much like a callback function. My class draw a document but every document must drawn differently. So I want to assign a function (written outside of the class) into one of the members of the class and then call it when I want to draw the document. This function mostly is responsible for transforming objects according to each specific document. Here is my class: class CDocument { public: CDocument(); ~CDocument(); void *TransFunc(); } void Transform() { } int main() CDocument* Doc = new CDocument(); Doc->TransFunc = Transform(); } I know that this is probably simple question, but I couldn't find the answer by googling or searching SO.

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  • Query with UDF works in Access but gives Undefined function in expression (Err 3085) in Excel

    - by ronwest
    I have an Access table with a date/time field. I wanted to make a composite Key field out of the date/time field and 3 other text fields in the same format as the matching Key field in another database. So I concatenated the 3 text fields and wrote a User-Defined-Function in a Module to output the date field as a string in the format "YYYYMMDD". Public Function YYYYMMDD(dteDate As Date) As String YYYYMMDD = Format(dteDate, "YYYYMMDD") End Function I can then successfully run my queries in Access and it all works fine. But when I set up some DAO code in Excel and try to run the query that works fine within Access... db.Execute "qryMake_tblValsDailyAccount" ...Excel gives me the "Undefined function in expression. (Error 3085)" error. To me this is a bug in Excel and/or Access, because the (Excel) client shouldn't need to know anything about the internal calculations that normally take place perfectly in the (Access) server when in isolation. Excel should send the querydef (name with no parameters) to the server, let the server do its work then receive the answers. Why does it need to get involved with a function internal to the server? Does anyone know a way around this?

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  • Set the output of a function equal to a variable

    - by ryno
    How would i set the output of a custom php function to a variable? The function is: function getRandomColor1() { global $cols; $num_cols = count($cols); $rand = array_rand($cols); $rand_col = $cols[$rand]; echo $rand_col; unset($cols[$rand]); } How would i set getRandomColor1 equal to $RandomColor1? I need it to be a variable so I can use it in css like: #boxone1 { height: 150px; width: 150px; background: <?=$RandomColor1?>; float: left; } If its not possible to set it as a variable, how else could i put the output of the function into css?

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  • What is the point of function pointers?

    - by gramm
    Hi, I have trouble seing the utility of the function pointers. I guess it may be useful in some cases (they exist, after all), but I can't think of a case where it's better or unavoidable to use a function pointer. Could you give some example of good use of function pointers (in C or C++)? Many thanks :)

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  • function in c language

    - by sandy101
    Hello, I am practice the function in c and come across to the program .... include int main() { float a=15.5; char ch ='C'; printit(a,ch); return 0; } printit(a,ch) { printf("%f\n%c",a,ch); } I want to know that why the above program compile and not give the error as i understood so for is ... 1) The function in c must be declared with the specific prototype (but this program does not contain the prototype ) 2)why the program give the output 'x'for the char variable 3)can the function in c are capable of accepting the value without being declared about type in parameters like what has done in the function declaration .... plz.... help

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  • Invoking jQuery function without an element

    - by Sandman
    So, I use jQuery quite extensively and I am well aware of the "right" way to do the below, but there are times where I want to solve it in a more generic way. I'll explain. So, I may have a link, like this: <a href='menu' class='popup'>Show menu</a>. Now, I have a jQuery function that fires on click for all a.popup that takes the href-attribute and shows the <div id='menu'></div> item (in this case). It also handles URL's if it can't find a DOM item with that ID. No problem here. But, there are times when I don't have the same control over the coe where I can create a selectable target that way. Either because the code isn't created by me or because it is created through a chain of function that would all need a huge ovrhaul which I won't do. So, from time to time, I would like to have this code: <a href="javascript:popup('menu')">Show menu</a> This would be in a case where I can only submit the label and the HREF for a link. No class, no nothing. Problem here is that the function popup() has no idea about what element invoked it, and in most cases that's not a problem for me, since I only need to know where the mouse cursor was upon invokation. But in some cases, I use someone elses jQuery functions, like qTip or something else. so I still want to fire off qTip(); when clicking a link that runs this JS function, but what do I attach it to to make it show? I can't just runt $().qTip(); because that implies $(this) and "this" is undefined inside the function. So how do I do it? Any ideas?

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  • C++: How do I pass a function(without knowing its parameters) to another function?

    - by Ninja
    Hi all. I'm trying to create a function that will store and repeat another function given as a parameter for a specific amount of time or repeats given. But when you want to pass a function as a parameter you have to know all of its parameters before hand. How would I do if I wanted to pass the function as one parameter, and the parameters as another? void AddTimer(float time, int repeats, void (*func), params); // I know params has no type and that (*func) is missing parameters but it is just to show you what I mean Thanks in advance

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  • Start a thread using a method pointer

    - by Michael
    Hi ! I'm trying to develop a thread abstraction (POSIX thread and thread from the Windows API), and I would very much like it to be able to start them with a method pointer, and not a function pointer. What I would like to do is an abstraction of thread being a class with a pure virtual method "runThread", which would be implanted in the future threaded class. I don't know yet about the Windows thread, but to start a POSIX thread, you need a function pointer, and not a method pointer. And I can't manage to find a way to associate a method with an instance so it could work as a function. I probably just can't find the keywords (and I've been searching a lot), I think it's pretty much what Boost::Bind() does, so it must exist. Can you help me ?

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  • PHP callback function not being called

    - by Industrial
    Hi everyone, I've got the following code: function _callback_memcache_failure($host, $port) { print "memcache '$host:$port' failed"; } $this->memcache = new Memcache; $this->memcache->addServer('192.168.1.35', '11211', 0, 50, 10, TRUE, _callback_memcache_failure('192.168.1.35','11211')); The server is online and running (verified!), but the Failure callback function is being called at each connection. Why is that? Reference: PHP documentation: Memcache::addServer - failure_callback Allows the user to specify a callback function to run upon encountering an error. The callback is run before failover is attempted. The function takes two parameters, the hostname and port of the failed server .

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  • jquery - using a function id in a different function

    - by andrew
    Hi, I have a function like that: function loadcategory(id) { jQuery("#categoryArea").load("ajax_post_category.php?catid="+id+""); } im getting id via link like that: <a href='javascript:loadcategory(".$row['catid'].");'> i would like to use function loadcategory(id)'s id in a different function. for example: function different() { jQuery("#different").load("ajax_post_category.php?catid="+loadcategory(id)+""); } as you can see i wanted to use +loadcategory(id)+, however i havent gotten any values. well, how can i get that value by jquery? i dont know, can anyone tell me the true way? regards

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  • Periods in Javascript function definition (function window.onload(){}) [closed]

    - by nemec
    Possible Duplicate: JavaScript Function Syntax Explanation: function object.myFunction(){..} I've seen some (legacy) javascript code recently that looks like: function window.onload(){ // some code } This doesn't look like valid javascript to me since you can't have a period in an identifier, but it seems to work in IE8. I assume it's the equivalent of: window.onload = function(){} I've tried the same code in Chrome and IE9 and both of them raise syntax exceptions, so am I correct in thinking that this "feature" of IE8 is some non-standard function definition that should be replaced? The code in question is only sent to IE browsers, so that's probably why I haven't run into this issue before.

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  • Trouble passing a template function as an argument to another function in C++

    - by Darel
    Source of the problem -Accelerated C++, problem 8-5 I've written a small program that examines lines of string input, and tallies the number of times a word appears on a given line. The following code accomplishes this: #include <map> #include <iostream> #include <string> #include <vector> #include <list> #include <cctype> #include <iterator> using std::vector; using std::string; using std::cin; using std::cout; using std::endl; using std::getline; using std::istream; using std::string; using std::list; using std::map; using std::isspace; using std::ostream_iterator; using std::allocator; inline void keep_window_open() { cin.clear(); cout << "Please enter EOF to exit\n"; char ch; cin >> ch; return; } template <class Out> void split(const string& s, Out os) { vector<string> ret; typedef string::size_type string_size; string_size i = 0; // invariant: we have processed characters `['original value of `i', `i)' while (i != s.size()) { // ignore leading blanks // invariant: characters in range `['original `i', current `i)' are all spaces while (i != s.size() && isspace(s[i])) ++i; // find end of next word string_size j = i; // invariant: none of the characters in range `['original `j', current `j)' is a space while (j != s.size() && !isspace(s[j])) ++j; // if we found some nonwhitespace characters if (i != j) { // copy from `s' starting at `i' and taking `j' `\-' `i' chars *os++ = (s.substr(i, j - i)); i = j; } } } // find all the lines that refer to each word in the input map<string, vector<int> > xref(istream& in) // works // now try to pass the template function as an argument to function - what do i put for templated type? //map<string, vector<int> > xref(istream& in, void find_words(vector<string, typedef Out) = split) #LINE 1# { string line; int line_number = 0; map<string, vector<int> > ret; // read the next line while (getline(in, line)) { ++line_number; // break the input line into words vector<string> words; // works // #LINE 2# split(line, back_inserter(words)); // #LINE 3# //find_words(line, back_inserter(words)); // #LINE 4# attempting to use find_words as an argument to function // remember that each word occurs on the current line for (vector<string>::const_iterator it = words.begin(); it != words.end(); ++it) ret[*it].push_back(line_number); } return ret; } int main() { cout << endl << "Enter lines of text, followed by EOF (^Z):" << endl; // call `xref' using `split' by default map<string, vector<int> > ret = xref(cin); // write the results for (map<string, vector<int> >::const_iterator it = ret.begin(); it != ret.end(); ++it) { // write the word cout << it->first << " occurs on line(s): "; // followed by one or more line numbers vector<int>::const_iterator line_it = it->second.begin(); cout << *line_it; // write the first line number ++line_it; // write the rest of the line numbers, if any while (line_it != it->second.end()) { cout << ", " << *line_it; ++line_it; } // write a new line to separate each word from the next cout << endl; } keep_window_open(); return 0; } As you can see, the split function is a template function to handle various types of output iterators as desired. My problem comes when I try to generalize the xref function by passing in the templated split function as an argument. I can't seem to get the type correct. So my question is, can you pass a template function to another function as an argument, and if so, do you have to declare all types before passing it? Or can the compiler infer the types from the way the templated function is used in the body? To demonstrate the errors I get, comment out the existing xref function header, and uncomment the alternate header I'm trying to get working (just below the following commment line.) Also comment the lines tagged LINE 2 and LINE 3 and uncomment LINE 4, which is attempting to use the argument find_words (which defaults to split.) Thanks for any feedback!

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  • SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    SQL Server 2012 introduces new analytical function LEAD() and LAG(). This functions accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. Instead of creating new table, I will be using AdventureWorks sample database as most of the developer uses that for experiment. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. When we look at above resultset it is very clear that LEAD function gives us value which is going to come in next line and LAG function gives us value which was encountered in previous line. If we have to generate the same result without using this function we will have to use self join. In future blog post we will see the same. Let us explore this function a bit more. This function not only provide previous or next line but it can also access any line before or after using offset. Let us fun following query, where LEAD and LAG function accesses the row with offset of 2. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result. You can see the LEAD and LAG functions  now have interval of  rows when they are returning results. As there is interval of two rows the first two rows in LEAD function and last two rows in LAG function will return NULL value. You can easily replace this NULL Value with any other default value by passing third parameter in LEAD and LAG function. Let us fun following query. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID,2,0) OVER (ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where NULL are now replaced with value 0. Just like any other analytic function we can easily partition this function as well. Let us see the use of PARTITION BY in this clause. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, LEAD(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LeadValue, LAG(SalesOrderDetailID) OVER (PARTITION BY SalesOrderID ORDER BY SalesOrderDetailID ) LagValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO Above query will give us following result, where now the data is partitioned by SalesOrderID and LEAD and LAG functions are returning the appropriate result in that window. As now there are smaller partition in my query, you will see higher presence of NULL. In future blog post we will see how this functions are compared to SELF JOIN. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • 1D Function into 2D Function Interpolation

    - by Drazick
    Hello. I have a 1D function which I want to interpolate into 2D function. I know the function should have "Polar Symmetry". Hence I use the following code (Matlab Syntax): Assuming the 1D function is LSF of the length 15. [x, y] = meshgrid([-7:7]); r = sqrt(x.^2 + y.^2); PSF = interp1([-7:7], LSF, r(:)); % Sometimes using 'spline' option, same results. PSF = reshape(PSF, [7, 7]); I have few problems: 1. Got some overshoot at the edges (As there some Extrapolation). 2. Can't enforce some assumptions (Monotonic, Non Negative). Is there a better Interpolation method for those circumstances? I couldn't find "Lanczos" based interpolation I can use the same way as interp1 (For a certain vector of points, in "imresize" you can only set the length). Is there such function anywhere? Has anyone encountered a function which allows enforcing some assumptions (Monotonically Decreasing, Non Negative, etc..). Thanks.

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