Solution: Direct access to Printer I/O lines

jkndeja at my-deja.com jkndeja at my-deja.com
Mon Dec 18 14:44:57 CET 2000


Hi Alex,

OK, without (yet...) going too deep into the more-generalised-and-
interesting patterns discussion developing here:

If I/you/we don't want singleton objects, but _do_ want to avoid having
multiple processes accessing a single port, how about this:

class directlpt:
    def __init__(self, LPTNum):
        # gives me access to an LPT port
        ...
    def inb(self, offset):
        # I'm always allowed to read the port
        ...
    def inw(self, offset):
        # likewise
        ...
    def claim(self, timeout = ??):
        # I have to claim the resource to be able to write to it
        ...
    def outb(self, offset)
        # otherwise I get an exception (IOERrror?) here...
    def outb(self, offset)
        # and here

    def release(self):
        # I release it for other processes as soon as I'm done



    Thanks
    Jon N


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