python function call syntax ... result = foo() ['abc']

number = droid.readPhoneState()['result']['incomingNumber']

What are 'result' and 'incomingNumber' in this syntax -- are they not parameters?开发者_如何学JAVA

How are they related to the function readPhoneState?

import android

droid = android.Android()
droid.startTrackingPhoneState()

number = droid.readPhoneState()['result']['incomingNumber']

if number != None:
  droid.speak('Call from '+str(number))
else:
  droid.makeToast('No incoming call')

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droid.readPhoneState() returns a dict of dicts. Equivalent code:

outerDict = droid.readPhoneState()
innerDict = outerDict['result']
number = innerDict['incomingNumber']

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result and incomingNumber are keys to a dictionary or an instance of a class that implements method __getitem__. This means that readPhoneState() returns a dictionary object, which supposed to have a key result and the corresponding value is a dictionary object which supposed to have a key incomingNumber.

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the interpretation is that droid.readPhoneState() returns a dict, whose value corresponding to the key 'result' is another dict.

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readPhoneState() is the method and it returns a dictionary object.

The dictionary object contains the property result which is also a dictionary object containing the property incomingNumber

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Supposedly, readPhoneState() returns a dictionary where values are, again, dictionaries.

With this syntax, you get the dictionary - returned by readPhoneState() - associated with key 'result' and ask it for the value whose key is 'incomingNumber'.