[Tutor] functions

[Yann Le Du]

> Exercise for the interested reader: What will this code print?  Why?
>
> >>> d = 'foo'
> >>> def func():
> ...     print d
> ...     d = 'bar'
> ...     print d

I thought this would print 'foo' then 'bar' but actually it just fails :

UnboundLocalError: local variable 'd' referenced before assignment

Apparently, it is the  d='bar'  assignment that conflicts with the  print
d  just above. This means that Python looks forward, understands that d is
local because of  d='bar' , then goes back to  print d  and then says that
d is not yet defined ?

Y