Python: pass statement in lambda form
lambdas can only contain expressions - basically, something that can appear on the right-hand side of an assignment statement. pass is not an expression - it doesn't evaluate to a value, and a = pass is never legal.
Another way of thinking about it is, because lambdas implicitly return the result of their body, lambda: pass is actually equivalent to:
def f(): return passWhich doesn't make sense. If you really do need a no-op lambda for some reason, do lambda: None instead.
That is an error because after the colon you have to put the return value, so:
lambda: passis equal to:
def f(): return passthat indeed makes no sense and produces a SyntaxError as well.
The return value of a function without a return statement is None. You can see this from the simple pass function that is defined in the OP:
>>> def f():... pass... >>> print f()NoneIf you are looking for a lambda function that is equivalent to this "no-op" function, then you can use:
lambda: NoneFor example:
>>> f = lambda: None>>> print f()None