C/C++ :: Design Pattern For Extensible Function Parameter
Oct 26, 2014
I need to design an interface(a function prototype) that takes an argument which is used to pass information.
The information can be passed by independent modules and third party softwares and hence can vary today and in future.
Basically, the function interface(arg1, info) caters a niche service to many independent applications and needs to process based on requirements passed by applications in the argument(info, in example).
I am looking for a design pattern for the function parameter - info.
Should I use a void pointer that can be casted to respective application specific class in the function ? will this be a good C++ design ?
or should I take this parameter to be a pointer to a generic abstract class that points to the respective application specific specialization ?
Do we have some design pattern to address this so as to handle other unforeseen challenges ?
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Oct 26, 2014
I need to design an interface(a function prototype) that takes an argument which is used to pass information.
The information can be passed by independent modules and third party softwares and hence can vary today and in future.
Basically, the function interface(arg1, info)caters a niche service to many independent applications and needs to process based on requirements passed by applications in the argument(info, in example).
I am looking for a design pattern for the function parameter - info.
Should I use a void pointer that can be casted to respective application specific class in the function ? will this be a good C++ design ?
or should I take this parameter to be a pointer to a generic abstract class that points to the respective application specific specialization ?
Do we have some design pattern to address this so as to handle other unforeseen challenges ?
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Dec 11, 2014
Any design pattern allows to describe operation like the following.
MyFunctionObject f;
//Init f...
MyFunctionObject g;
//Init g...
MyFunctionObject h = f(g) + g;
[Code] .....
I'm interested in design pattern which permits to model this kind of structure, if there's of course...
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Sep 26, 2013
How to write a printPattern() function?
The function takes in a parameter i.e. a char pointer. It handles the parameter as a Cstyle string i.e. a NULL terminated char array. It does not make use of the stringclass or its associated functions. In other words, the function examines every char element in the array until it encounters the terminating NULL character.
Starting from this int main :
int main() {
char string1[] = "Application of C++";
printPattern(string1);
}
[Code].....
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Jan 21, 2015
I am looking into some design pattern which works for validation.
I thought about using strategy but not sure whether its correct or not
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Feb 24, 2014
I am looking a good design pattern that takes a combination of a Observer Design Pattern and Command Design Pattern.
Observer Design Pattern:
Subject - ISystem
ConcreteSubject - "Different Types of Systems"
Observer - INotifier
ConcreteObserver - "Different Types of Notifier's"
Command Design Pattern: Used to create a task. "Different Types of Task" ....
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Oct 17, 2013
In the following code example of the State Design Pattern, in the main code at the bottom it defines an instance of class Machine, and then calls Machine::off;. Why doesn't it instead call fsm.off;?
Machine fsm;
Machine::off;
Then I tried imitating that by adding a class Abba, and then doing:
Abba a;
Abba::DoStuff();
but that didn't work. Why?
Full code example:
// StatePattern.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
using namespace std;
class Machine {
class State *current;
[Code] ....
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Nov 1, 2014
I'm building a Windows Form Application using MVP Design Pattern; the application is quite simple, it just calculates the sum of two number; So I have a form in which are located tree textbox: number1 number2 and result, plus a button to perform the action.
interface ICalcView {
string firstN { get; set; }
string firstN {get; set;}
string result { get; set; }
[Code] ....
Do you think that is a good base to start? Any code example to understand the execution flow and how to handle events?
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Jan 17, 2013
I have the following code where I use the singleton design pattern, but I get the warning:
warning C4715: 'CM::Instance' : not all control paths return a value
Code:
CM& CM::Instance() {
DWORD dwWaitResult = WaitForSingleObject(mutex, INFINITE);
switch(dwWaitResult) {
case WAIT_OBJECT_0:
[Code] ....
How can I fix this warning?
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Jul 9, 2014
I was going through Singleton design pattern and get to know that objects can be created only by static function of that class and constructors are make private.
My question is, why assignment operators are not made private through which we can create a copy of already existing object.
I tried below code and assignment works, so I have new object sc3. I know that its referring to memory of sc1 but finally I was able to create object without using static function.
Also, why copy constructor not made as private.
Below is code:
#include <iostream>
using namespace std;
class Singleton {
private:
static bool instanceFlag;
[Code] .....
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Sep 28, 2014
My errors are at the end of the program in two function calls within the definition of the InsertByValue function. g++ does not seem to recognize NumArray as a valid parameter.
#include <iostream>
#include <assert.h>
using namespace std;
const int CAPACITY = 20;
/* Displays the content of an int array, both the array and the size of array will be passed as parameters to the function
@param array: gives the array to be displayed
@param array_size: gives the number of elements in the array */
void DisplayArray (int array[], int array_size);
[Code] ....
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Nov 5, 2013
How to create a diagonal pattern by the given function
void diagonal(int size, char op)
The function takes in 2 arguments, size and op and displays a diagonal line of op char. for example, diagonal (5,#) will produce the following output.
#
#
#
#
#
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Oct 11, 2014
I need to make a recursive function(s) which prints the hour glass pattern. This is my code so far:
void HourGlass(int n) {
if (n==1){
cout<<"*"<<endl;
cout<<"*"<<endl;
} else {
stars(n-2);
HourGlass(n-2);
[Code] ....
Problem is, it doesn't print the spaces in front of the pattern. This is what it prints:
*****
***
*
*
***
*****
and this is what it is supposed to print:
*****
***
*
*
***
*****
Do I make a separate function for the spaces? How do I go about it?
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Jul 6, 2014
error says "cannot convert 'int*' to 'int' in function main()
and also
type mismatch in parameter in function sort(int,int)
Heres the code:
#include<iostream.h>
#include<conio.h>
void main() {
void sort(int,int);
clrscr();
[Code] .....
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Oct 28, 2013
I have a class as below:
// RemoteControlMonitor.H
typedef void (*keyaction)(unsigned int key);
class RemoteControlMonitor {
private:
keyaction rph;
keyaction rrh;
[Code] .....
But I got compile error as below:
RemoteControlMonitor.H:58: invalid type `void *' for default argument to `void (*)(unsigned int)'
rcx1.C: In function `void __static_initialization_and_destruction_0(int, int)':
rcx1.C:54: ANSI C++ forbids implicit conversion from `void *' in default argument
What can I do?
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Apr 17, 2014
How I can delete a parameter in a function .
int *buildTrail(int antIndex, int start, double *pheromones) {
int *trail = new int[tabu];
bool *visited = new bool[tabu];
trail[0] = start;
visited[start] = true;
[Code] ....
If I comment all lines includes visited word , no exception occurs , Otherwise , exception throws.
Simply put , How can i delete visited parameter as long as its role has been finished?
.
.
.
delete visited ;
return trail;
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Jan 7, 2015
gcc v.8.3 -std=gnu++11
[URL]
I'm trying to pass a function as a parameter and failing. It seems simple, until I get the error messages.
Here is the code:
class MinimalSolver {
typedef double (*func)(double sum, double char);
void driver();
[Code]....
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May 17, 2013
void foo(FILE *f1, FILE **f2) {
fputs("...", f1);
fputs("...", *f2);
} int main(void) {
FILE *fp1 = fopen(...),
*fp2 = fopen(...);
if(fp1 && fp2) {
foo(fp1, &fp2);
...
}
...
}
Forever, I've passed FILE objects into functions like the first parameter; I've never had an issue reading or writing files using that form - no file errors, no compiler warnings, etc. Recently, I saw the second parameter form, and wondered why that was?
I still don't quite get this part of pointers. What's the second parameter form doing differently than the first when the first version *appears* to work as intended??
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Oct 6, 2014
How come when we pass an array as a parameter to a function, the entire array is copied and is available to function?
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Jan 11, 2015
Is there any function which can return parameter list of a function.
For example : get_param(f(int x,char y )) return parameter x-> int y-> char
and f_name ->f
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May 2, 2013
Write a program that inputs 10 integers from the console into an array, and removes the duplicate array elements and prints the array. By removing, I mean that you should make it appear as if the elements hadn't been there. You may assume that all the integers are between 0 and 100, Write at least 1 function in addition to the main function, and pass an array into that function as a parameter. e.g.
Please enter your 10 numbers: 1 2 3 4 5 6 7 8 9 10 The array contains: 1 2 3 4 5 6 7 8 9 10
Please enter your 10 numbers: 1 1 3 3 3 6 7 8 9 9 The array contains: 1 3 6 7 8 9
Please enter your 10 numbers: 1 1 1 1 1 1 1 1 1 1 The array contains: 1
The bolded area is where I'm having trouble. How I can go about doing this, passing an array into the function as a parameter?
Here is my code:
#include "stdafx.h"
#include <iostream>
using namespace std;
int main () {
const int MAX = 10;
int a[MAX] = {0};
int i;
[Code]...
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Dec 26, 2013
Pseudocode:
template<typename T /*, some parameter for member_function */>
class Foo {
public:
void someFunction() {
T t;
t.member_fuction(...);
} }
I'm trying to make the call to T::member_function a templated value because member_function might vary by name in my scenario. Since std::mem_fn isn't a 'type', i can't do something like Foo<std::string, std::mem_fn(&std::string::clear)> foo;
I also want to take into account that member_function might have more than one parameter. That is, the first parameter will always be something known but there might be other defaulted parameters.
The only thing I can think of is to make a proxy structure, something like this:
template<typename T, T> struct proxy;
template<typename T, typename R, typename... Args, R (T::*member_function)(Args...)>
struct proxy<R (T::*)(Args...), member_function> {
R operator()(T &obj, Args.. args) {
return (obj.*member_function)(std::forward<Args>(args)...);
} }
Which would then allow me to do (for example) this:
Foo<std::string, proxy<void(std::string::*)(), &std::string::clear> >
when Foo is implemented like this:
template<typename T, typename member_function>
class Foo {
public:
void someFunction() {
T t;
member_function()(t);
} };
That implementation works for me.
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Nov 26, 2014
#include <iostream>
#include <initializer_list>
using namespace std;
void doSomething(std::initializer_list<int> list) {
} int main() {
doSomething({2,3,6,8});
return 0;
}
I write a small piece of code like above. But I can not compile it successfully. I try it both with and without the line "using namespace std", but nothing worked.
The error list: Symbol 'initializer_list' could not be resolved
I use Eclipse CDT and GCC 4.9.1.
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Sep 11, 2014
is it true or false
a function like void myfun(int num){} can receive type "int var" but can't receive type "const int var"
AND
a function like void myfun(const int num){} can receive both type "int var" and also type "const int var"
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May 2, 2013
I have been working on this all day, and its due in like an hour and a half. I have done everything the program wants except the last part. Here is the assignment:
Write a program that inputs 10 integers from the console into an array, and removes the duplicate array elements and prints the array. You may assume that all the integers are between 0 and 100, Write at least 1 function in addition to the main function, and pass an array into that function as a parameter. e.g.
Please enter your 10 numbers: 1 2 3 4 5 6 7 8 9 10
The array contains: 1 2 3 4 5 6 7 8 9 10
Please enter your 10 numbers: 1 1 3 3 3 6 7 8 9 9
The array contains: 1 3 6 7 8 9
Please enter your 10 numbers: 1 1 1 1 1 1 1 1 1 1
The array contains: 1
The bolded part is what I cant get to work. I have tried this and it keeps telling me I have not identified the items when I have.
Here is my code:
#include "stdafx.h"
#include <iostream>
using namespace std;
[Code]....
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Oct 20, 2013
How can I pass a function as a parameter? I have a class that I'm trying to reuse and one of the methods in this class need to take three parameters, two ints and a function. In other words I want to be able to call a custom function every time this method is invoked when used in other classes. The function I want to call will not return any values, its a void function.
In my Class:
void Utility::someFunction(int var1, int var2, void customFunction) {
int num1 = var1;
int num2 = var2;
[Code] .....
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