throw(std::runtime_error("I told you not to do instantiate me!"));
too_late = true;
cln::default_float_format = cln::float_format(17);
+
+ // add callbacks for built-in functions
+ // like ... add_callback(Li_lookuptable);
}
/** Assign a native long to global Digits object. */
_numeric_digits& _numeric_digits::operator=(long prec)
{
+ long digitsdiff = prec - digits;
digits = prec;
- cln::default_float_format = cln::float_format(prec);
+ cln::default_float_format = cln::float_format(prec);
+
+ // call registered callbacks
+ std::vector<digits_changed_callback>::const_iterator it = callbacklist.begin(), end = callbacklist.end();
+ for (; it != end; ++it) {
+ (*it)(digitsdiff);
+ }
+
return *this;
}
}
+/** Add a new callback function. */
+void _numeric_digits::add_callback(digits_changed_callback callback)
+{
+ callbacklist.push_back(callback);
+}
+
+
std::ostream& operator<<(std::ostream &os, const _numeric_digits &e)
{
e.print(os);
#include "ex.h"
#include <stdexcept>
+#include <vector>
#include <cln/complex.h>
namespace GiNaC {
+/** Function pointer to implement callbacks in the case 'Digits' gets changed.
+ * Main purpose of such callbacks is to adjust look-up tables of certain
+ * functions to the new precision. Parameter contains the signed difference
+ * between new Digits and old Digits. */
+typedef void (* digits_changed_callback)(long);
+
/** This class is used to instantiate a global singleton object Digits
* which behaves just like Maple's Digits. We need an object rather
* than a dumber basic type since as a side-effect we let it change
_numeric_digits();
_numeric_digits& operator=(long prec);
operator long();
- void print(std::ostream &os) const;
+ void print(std::ostream& os) const;
+ void add_callback(digits_changed_callback callback);
// member variables
private:
long digits; ///< Number of decimal digits
static bool too_late; ///< Already one object present
+ // Holds a list of functions that get called when digits is changed.
+ std::vector<digits_changed_callback> callbacklist;
};