I've a pointer to the function that can point to the function with one, two or more args.
double (*calculate)(int);
double plus(int a, int b){ return a+b; }
double sin(int a){ return Math::Sin(a); }
how is it possible for me to use
calculate = plus;
calculate = sin;
in the same program. Not allowed to change functions plus and sin. Writing in managed c++;
I've tried double (*calculate)(...); but that's not working.
The assignment of plus to calculate is a type violation, and when calling calculate later leads to undefined behavior, so anything (bad) can happen.
You might be interested in libffi (but I have no idea if it works with managed C++).
You can try use something like this:
struct data
{
typedef double (*one_type) ( int a );
typedef double (*other_type) ( int a, int b );
data& operator = ( const one_type& one )
{
d.one = one;
t = ONE_PAR;
return *this;
}
data& operator = ( const other_type& two )
{
d.two = two;
t = TWO_PAR;
return *this;
}
double operator() ( int a )
{
assert( t == ONE_PAR );
return d.one( a );
}
double operator() ( int a, int b )
{
assert( t == TWO_PAR );
return d.two( a, b );
}
union func
{
one_type one;
other_type two;
} d;
enum type
{
ONE_PAR,
TWO_PAR
} t;
};
double va( int a )
{
cout << "one\n";
}
double vb( int a, int b )
{
cout << "two\n";
}
This works fine:
data d;
d = va;
d( 1 );
d = vb;
d( 1, 2 );
