Question

When you want to print a bunch of variables in Python, you have quite a few options, such as:

for i in range(len(iterable)):
    print iterable[i].name

OR

map(lambda i: sys.stdout.write(i.name), iterable)

The reason I use sys.stdout.write instead of print in the second example is that lambdas won’t accept print, but sys.stdout.write serves the same purpose.

You can also print conditionally with the ternary operator:

map(lambda n: None if n % 2 else sys.stdout.write(str(n)), range(1, 100))

So it would be really handy if I could check an entire sequence for a condition that would warrant an exception in such a way:

map(lambda o: raise InvalidObjectError, o.name if not o.isValid else o(), iterable)

But that doesn’t work.
Is there such an object for raise in Python, and if so, where is it?

Answer 1

There is no Python “object” (built-in or in the standard library) for raise, you have to build one yourself (typical short snippet that goes in one’s util.py…!):

def do_raise(exc): raise exc

typically to be called as do_raise(InvalidObjectError(o.name)).