Re: [Python-ideas] exception based conditional expression, similar to if-else conditional expression

On 20 Aug 2009, at 16:25 , Steven D'Aprano wrote:

A better way of writing that would be:

x = y.evaluate(locals()) if hasattr(y, 'evaluate') else y

which have the bonus of working correctly even if y gets its evaluate() method via inheritance.

Another way, two lines instead of one:

try: x = y.evaluate(locals()) except AttributeError: x = y

A third method: make sure all objects you pass have an evaluate() method, even if they are a null-operation that just return self.

Fourth method: x = getattr(y, 'evaluate', lambda _: y)(locals())