I love code that self-documents and reads naturally, so I strive to name my routines and variables appropriately. When you are faced with the implementation of a conversion method, in generally the name is in the form "toB", where B is the result of the conversion, for example
rgb_values = color.toRgb()
The inverse, when we want to convert and integrate the conversion into an object's internal state, is generally in the form "fromB"
When you have a conversion function, things are slightly different: "From" assumes a different weight and meaning. To perform a conversion color object to rgb you can use either
rgb_values = colorToRgb(color)
rgb_values = rgbFromColor(color)
The second works best because the proximity and order of the terms resembles the one naturally established by the prepended nature of the routine call and the order of the two objects. Everything moves from right to left in the second example, and it reads naturally. The first solution is clumsier and disorganized. Similarly, the reverse conversion will be
color = colorFromRgb(rgb_values)
The conclusion is that when you write a conversion function, prefer the "From" naming exclusively, while for methods you can use "To" and "From" forms for different conversion directions.