syntax_sugars.rst

Syntax sugars

Aliases

Creating aliases for global variables and functions with cumbersome names can sometimes improve readability. In Taichi, this can be done by assigning kernel and function local variables with ti.static(), which forces Taichi to use standard python pointer assignment.

For example, consider the simple kernel:

@ti.kernel
def my_kernel():
  for i, j in field_a:
    field_b[i, j] = some_function(field_a[i, j])

The fields and function be aliased to new names with ti.static:

@ti.kernel
def my_kernel():
  a, b, fun = ti.static(field_a, field_b, some_function)
  for i,j in a:
    b[i,j] = fun(a[i,j])

Aliases can also be created for class members and methods, which can help prevent cluttering objective data-oriented programming code with self.

For example, consider class kernel to compute the 2-D laplacian of some field:

@ti.kernel
def compute_laplacian(self):
  for i, j in a:
    self.b[i, j] = (self.a[i + 1,j] - 2.0*self.a[i, j] + self.a[i-1, j])/(self.dx**2) \
                + (self.a[i,j + 1] - 2.0*self.a[i, j] + self.a[i, j-1])/(self.dy**2)

Using ti.static(), it can be simplified to:

@ti.kernel
def compute_laplacian(self):
  a,b,dx,dy = ti.static(self.a,self.b,self.dx,self.dy)
  for i,j in a:
    b[i,j] = (a[i+1, j] - 2.0*a[i, j] + a[i-1, j])/(dx**2) \
           + (a[i, j+1] - 2.0*a[i, j] + a[i, j-1])/(dy**2)

Note

ti.static can also be used in combination with if (compile-time branching) and for (compile-time unrolling). See :ref:`meta` for more details.

Here, we are using it for compile-time const values, i.e. the field/function handles are constants at compile time.