George Oliver wrote:
hi, I'm a Python beginner with a basic question. I'm writing a game
where I have keyboard input handling defined in one class, and command
execution defined in another class. The keyboard handler class
contains a dictionary that maps a key to a command string (like 'h':
'left') and the command handler class contains functions that do the
commands (like def do_right(self):),
I create instances of these classes in a list attached to a third,
'brain' class. What I'd like to have happen is when the player presses
a key, the command string is passed to the command handler, which runs
the function. However I can't figure out a good way to make this
happen.
I've tried a dictionary mapping command strings to functions in the
command handler class, but those dictionary values are evaluated just
once when the class is instantiated. I can create a dictionary in a
separate function in the command handler (like a do_command function)
but creating what could be a big dictionary for each input seems kind
of silly (unless I'm misunderstanding something there).
What would be a good way to make this happen, or is there a different
kind of architecture I should be thinking of?
You have lots of words, but no code, and no explanation of why you're
choosing this "architecture." So it's unclear just what to propose to
you, without sticking to generalities.
1) forget about getattr() unless you have hundreds of methods in your
map. The real question is why you need two maps. What good is the
"command string" doing you? Why not just map the keyvalues directly
into function objects?
2) Look at the following simple example, where I'm assuming that a
"keycode" is simply an ASCII character.
class Command(object):
def __init__(self):
pass
def doEnter(self):
print "Enter is done"
def doA(self):
print "A is done"
cmd = Command()
table = {
13: cmd.doEnter,
65: cmd.doA
}
print "trying 13"
key = 13
table[key]()
print "trying 65"
key = 65
table[key]()
3) As for rebuilding the dictionary, that just depends on where you
build it, and what it's lifetime is. If it's got enough lifetime, and
appropriate scope, you wouldn't have to rebuild anything.
4) Code up a first try, and when you get stuck, ask a specific question.
You said you're a beginner. So keep it as simple as possible.l
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