A while back, I shared my love for using Greek letters as variable names in my Python (3.4) code -- when, and only when, they are warranted for improved readability. For example, I like to see the following:
from math import pi as π c = 2 * π * r When I am copying mathematical formulas from publications, and Greek letters are used in that publication, I prefer to follow the text exactly as written. Up until today, every character I've tried has been accepted by the Python interpreter as a legitimate character for inclusion in a variable name. Now I'm copying a formula which defines a gradient. The nabla symbol (∇) is used in the naming of gradients. Python isn't having it. The interpreter throws a "SyntaxError: invalid character in identifier" when it encounters the ∇. I am now wondering what constitutes a valid character for an identifier, and how they were chosen. Obviously, the Western alphabet and standard Greek letters work. I just tried a few very weird characters from the Latin Extended range, and some Cyrillic characters. These are also fine. A philosophical question. Why should any character be excluded from a variable name, besides the fact that it might also be an operator? This might be a problem I can solve, I'm not sure. Is there a file that the Python interpreter refers to which defines the accepted variable name characters? Perhaps I could just add ∇. -- https://mail.python.org/mailman/listinfo/python-list
