type conversion

[Steven D'Aprano]

On Wed, 31 Dec 2008 12:35:20 -0800, Hamish McKenzie wrote:

> sometimes I want to be able to initialize an instance with a variety of
> different data types.

Type conversion is a bit of a misleading subject line. You're not really 
converting different types, just initialising from different types.

 
> as an obvious example I might want to initialize a 4x4 matrix with
> either 16 floats, a list/tuple or 16 floats, another matrix or a
> quaternion.
> 
> is there any other way to do it other than putting case statements in
> the __init__ method of the class, or having a Matrix.FromQuaternion(
> quat )?


You could have an external function qtom:

def qtom(quaternion):
    a, b, c, d = quaternion
    return Matrix([
        a, 0, 0, 0,
        0, b, 0, 0, 
        0, 0, c, 0, 
        0, 0, 0, d])


But the first two solutions seem reasonable to me, except of course 
Python doesn't have a case statement you have to use an if...elseif block.


-- 
Steven