Python uplift with two parameters

Question

What does it do raise A, B? And how does he differ from what he does raise A?

Some examples (works on python 2.7 interpreter):

class E(Exception):
    pass
e = E()

raise Exception, e
Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
__main__.E

raise Exception(e)
Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
Exception

raise (Exception, e)
Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
Exception

Thank!

Answer 1

raisesupports up to three arguments; the first two are the type and value, the third is the trace object to use for exclusion. Line:

raise Exception, value

usually exactly equivalent:

raise Exception(value)

therefore, we create an instance Exception()by passing the second value as an argument to the exception constructor.

, , E, Exception , , :

raise Exception, e

:

raise e

:

raise E, ()

None:

raise E, None

E ; , E; None raise E().

, raise Exception Python , .

raise:

, . : , . , ; None, , . , , .

, , . , raise Python 3, . PEP 3109 - Python 3000.