I've got a 2D array of different blocks, all inheriting from Block. I want to check if the block that I clicked on is a Dirt type block, like this:
clickedblock = getClickedBlock()
if isinstance(clickedblock, Dirt):
place a block
else:
don't place a block
I've heard that isinstance is bad, and should be avoided because it creates forks in code. What times would isinstance be good to use?
Another more cumbersome solution for my problem would be to have a field of Block called 'id' and then check if it equals some constant that means Dirt. But that sounds quite bad and more prone for mistake than the simple isinstance.
Your example seems like a legitimate use case of isinstance().
It's not that isinstance() is bad, often polymorphism can be used for the same purpose (which results in cleaner code in where the class is used).
But sometimes, isinstance() is what you need. For example, the pythonic way of detecting whether a variable is string or not is isinstance(var, basestring).