On Oct 10, 11:39 am, Ramon Crehuet <[EMAIL PROTECTED]> wrote: > Dear all, > I have a Fortran programming background and I have some difficulties in > understading how function wrappers work. I have delved into the subject > because of the new decorators, but I understand the decorator syntax. My > ignorance is more profound... Here is an example without decorators:
Functions are first-class values: this means they can be passed around, used in expressions, and returned from other functions in just the same way that ints, floats and other more obvious types. All a decorator is a function that takes the function you give it, and returns a new function. In your 'require_int' example, it returns the nested function 'wrapper'. The clever bit is that 'wrapper' remembers the argument to the decorator - func - (with value p1 in your example), and can call it later. Think of the 'def' statement as constructing an object which happens to be a function. It has a dictionary which is used for variable lookup so that it can remember 'func'. The def statement also binds this function object to a name: the name of the function. You can see some of the gory details if you go: def f(): print 42 dir(f) ... list of attributes of the function object. -- Paul Hankin -- http://mail.python.org/mailman/listinfo/python-list
