Kurage Notes

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Macros ​

Syntax ​

Concatnating: ##https://gcc.gnu.org/onlinedocs/cpp/Concatenation.html

Tricks (Meta Programming) ​

I like this one:

c
#define BINARY_UFUNC(name,intype0,intype1,outtype,exp) \
    void name(char** args, npy_intp const *dimensions, \
              npy_intp const *steps, void* data) { \
        npy_intp is0 = steps[0], is1 = steps[1], \
            os = steps[2], n = *dimensions; \
        char *i0 = args[0], *i1 = args[1], *o = args[2]; \
        int k; \
        for (k = 0; k < n; k++) { \
            intype0 x = *(intype0*)i0; \
            intype1 y = *(intype1*)i1; \
            *(outtype*)o = exp; \
            i0 += is0; i1 += is1; o += os; \
        } \
    }
#define RATIONAL_BINARY_UFUNC(name,type,exp) \
    BINARY_UFUNC(rational_ufunc_##name,rational,rational,type,exp)
RATIONAL_BINARY_UFUNC(add,rational,rational_add(x,y))
RATIONAL_BINARY_UFUNC(subtract,rational,rational_subtract(x,y))
RATIONAL_BINARY_UFUNC(multiply,rational,rational_multiply(x,y))
RATIONAL_BINARY_UFUNC(divide,rational,rational_divide(x,y))
RATIONAL_BINARY_UFUNC(remainder,rational,rational_remainder(x,y))
RATIONAL_BINARY_UFUNC(floor_divide,rational,
    make_rational_int(rational_floor(rational_divide(x,y))))
PyUFuncGenericFunction rational_ufunc_true_divide = rational_ufunc_divide;
RATIONAL_BINARY_UFUNC(minimum,rational,rational_lt(x,y)?x:y)
RATIONAL_BINARY_UFUNC(maximum,rational,rational_lt(x,y)?y:x)
RATIONAL_BINARY_UFUNC(equal,npy_bool,rational_eq(x,y))
RATIONAL_BINARY_UFUNC(not_equal,npy_bool,rational_ne(x,y))
RATIONAL_BINARY_UFUNC(less,npy_bool,rational_lt(x,y))
RATIONAL_BINARY_UFUNC(greater,npy_bool,rational_gt(x,y))
RATIONAL_BINARY_UFUNC(less_equal,npy_bool,rational_le(x,y))
RATIONAL_BINARY_UFUNC(greater_equal,npy_bool,rational_ge(x,y))

Note line2 of this macro: void name(...

  • Meta Programming (My understanding) - the code that codes itself
  • Every time we call a macro BINARY_UFUNC, the preprocessor expands the Macro into a function definition