C/C++ Extensions

Overview

Optional language extensions that provide a more ergonomic API: C11 _Generic macros for type-inferred function dispatch, C++ function overloads, and C++ operator overloads.

Why Use This?

These extensions let you write cleaner code by removing the need for explicit type suffixes. In C++ you can use natural operators like +, -, *, / on vectors and matrices.

C11 Generic Macros

Header: lm2/extensions/lm2_c11_generics.h

When compiling as C11 or later, type-generic macros are available so you can write:

lm2_v3_f32 a = lm2_v3_make_f32(1, 2, 3);
lm2_v3_f32 b = lm2_v3_make_f32(4, 5, 6);

lm2_v3_f32 sum = lm2_v3_add(a, b);  // Dispatches to lm2_v3_add_f32

The correct function is selected at compile time based on the argument types via _Generic.

Disable: Define LM2_NO_GENERICS before including headers.

C++ Function Overloads

Header: lm2/extensions/lm2_cpp_generics.h

When compiling as C++, function overloads are provided:

lm2_v3_f32 a = lm2_v3_make_f32(1, 2, 3);
lm2_v3_f64 b = lm2_v3_make_f64(1, 2, 3);

lm2_v3_f32 r1 = lm2_v3_add(a, a);  // Calls lm2_v3_add_f32
lm2_v3_f64 r2 = lm2_v3_add(b, b);  // Calls lm2_v3_add_f64

Disable: Define LM2_NO_GENERICS before including headers.

C++ Operator Overloads

Header: lm2/extensions/lm2_cpp_operators.h

When compiling as C++, operator overloads are available for vectors, ranges, and matrices:

lm2_v3_f32 a = lm2_v3_make_f32(1, 2, 3);
lm2_v3_f32 b = lm2_v3_make_f32(4, 5, 6);

lm2_v3_f32 sum  = a + b;    // lm2_v3_add_f32
lm2_v3_f32 diff = a - b;    // lm2_v3_sub_f32
lm2_v3_f32 prod = a * b;    // lm2_v3_mul_f32
lm2_v3_f32 quot = a / b;    // lm2_v3_div_f32

float x = a[0];             // subscript operator

Disable: Define LM2_NO_CPP_OPERATORS before including headers.

Subscript Operator

All vector, matrix, and range types support operator[] in C++ for element access:

lm2_v3_f32 v = lm2_v3_make_f32(1, 2, 3);
float y = v[1];   // 2.0f
v[0] = 10.0f;     // modify x component

lm2_m4x4_f32 m = lm2_m4x4_identity_f32();
float diag = m[0]; // m00

Bounds are checked with LM2_ASSERT.

Automatic Inclusion

When including <lm2.h>, extensions are automatically included based on the compiler:

• C++: Both lm2_cpp_generics.h and lm2_cpp_operators.h are included
• C11+: lm2_c11_generics.h is included
• Pre-C11 C: No extensions

To opt out, define LM2_NO_GENERICS and/or LM2_NO_CPP_OPERATORS before including any headers.