My script executes depending on user’s input, like this:
while option != e
option = input("What to do? ")
if option == 'l':
sh.send('lock')
elif 's1':
sh.send('start','program1')
elif 's2':
sh.send('start','program2)
The problem is that I can have over 15 different choices, so I would like to make it cleaner using dicts, but I can’t get it to work. This is what I did. In the class init for sh:
self.operations = {"l": lambda: self.send('lock'),
"s1": lambda x: self.send('start', x),
"s2": lambda x: self.send('start', x)}
And so on. Further down in the class:
def user_input(self, key):
return self.operations[key]
And finally the input part of my script is much cleaner
while option != e
option = input("What to do? ")
try:
sh.user_input(option)()
except KeyError:
print('Invalid Operation')
This is as far as I got, and while it works for options without parameters, how can I make it work also for commands that need a second parameter?
Advertisement
Answer
To create a dispatcher, you need to combine the function/dictionary/lambdas like this:
def operations(self, key, x):
return {
"l": lambda: self.send('lock'),
"s1": lambda: self.send('start', x),
"s2": lambda: self.send('start', x)
}.get(key, lambda: None)
which you can call with self.operations("s1", 2). To evaluate it and get the result, you may need to do self.operations("s1", 2)().
Or, you need a value evaluated and returned, you can also write the function with the () at the end:
def operations(self, key, x):
return {
"l": lambda: self.send('lock'),
"s1": lambda: self.send('start', x),
"s2": lambda: self.send('start', x)
}.get(key, lambda: None)()
lambda: None, is the default for what happens if no valid key is passed. It needs to be a lambda to avoid getting: TypeError: 'NoneType' object is not callable (because None itself isn’t), but you can change this to something that makes sense for your purpose.