I have a class below:
class Test:
def alpha(self):
a = 5
return a
def bravo(self):
alp = self.alpha()
c = 2
solution = alp + c
print(solution)
return solution
and I am trying to write a new class that calls Test.bravo(),
but having an error due to Test.alpha inside of it.
How can I write a new class? below is what I did:
class Test2:
def charlie(self):
call_bravo = Test.bravo(self)
print(call_bravo)
def main():
tst = Test()
tst.bravo()
tst2 = Test2()
tst2.charlie()
if __name__ == '__main__':
main()
The solution below works correctly.
class Test:
def alpha(self):
a = 5
return a
def bravo(self):
alp = self.alpha()
c = 2
solution = alp + c
print(solution)
class Test2:
def charlie(self):
call_bravo = Test()
res = call_bravo.bravo()
print(res)
def main():
tst = Test()
tst.bravo()
tst2 = Test2()
tst2.charlie()
if __name__ == '__main__':
main()
I expect that your error is because you're trying to invoke a method of class Test to operate on an object of Test2.
tst2.Charlie() invokes
Test.bravo(tst2), which invokes
tst2.alpha()
Your problem is that there is no such routine: the only alpha in your design is a method of Test; there is no alpha method for Test2.
In short, you have a fatal design error. Sort out what functionality you want in each class.
Related
I just began the long and painful journey in Python Class Objects and try this:
class UgcObject:
def __init__(self, strPlateformeOld, strIdOld):
self.strPlateformeOld = strPlateformeOld
self.strIdOld = strIdOld
def GetApiUpdatedMetadata(self):
if self.strPlateforme == "youtube":
return True
def GetblnUpdatePossible(self):
return GetApiUpdatedMetadata()
if __name__ == '__main__':
ugc_test = UgcObject("youtube","id")
print(ugc_test.GetblnUpdatePossible())
I got an error message: NameError: name 'GetApiUpdatedMetadata' is not defined
I don't get why considering that I believe the GetApiUpdatedMetadata is declared and above the method that calls it.
What did I did wrong?
If you are trying to call another method in the same class it should have self. in front of it, and the variable name self.strPlateforme is wrong:
class UgcObject:
def __init__(self, strPlateformeOld, strIdOld):
self.strPlateformeOld = strPlateformeOld
self.strIdOld = strIdOld
def GetApiUpdatedMetadata(self):
if self.strPlateformeOld == "youtube":
return True
def GetblnUpdatePossible(self):
return self.GetApiUpdatedMetadata()
if __name__ == '__main__':
ugc_test = UgcObject("youtube","id")
print(ugc_test.GetblnUpdatePossible())
I'm new to python and the main() method and class def's are confusing me. I'm trying to create a bloom filter and my program keeps terminating because I don't think I'm calling things correctly.
class BloomFilter(object):
def __init__(self, numBits, numHashFunctions):
self.numBits = numBits
self.bitArray = [0] * numBits
self.hash = bloomFilterHash(numBits, numHashFunctions)
def insert(self, key):
def lookup(self, key):
def rand_inserts(self,num):
def main(): #not sure if i should put this inside or outside class
bloomfilter = BloomFilter(100,5)
bloomfilter.rand_inserts(15)
if __name__ == '__main__':
BloomFilter().main()
So if I wanted to create a bloom filter with 100 numBits and 5 hash functions, should i call that under the if __name__ == '__main__' or under def main()? I'm not sure if I'm calling these correctly as I'm much more familiar with Java. thanks!
def main():
bloomfilter = BloomFilter(100,5)
bloomfilter.rand_inserts(15)
the name == '__main__' clause is to make sure your code only runs when the module is called directly, not, for instance, if you are importing something from the module in another module. main() is not a special method for a python class, so I believe your objective here, in a simplified way, is the following:
class BloomFilter(object):
def __init__(self, numBits, numHashFunctions):
self.numBits = numBits
self.bitArray = [0] * numBits
self.hash = bloomFilterHash(numBits, numHashFunctions)
if __name__ == '__main__':
# creates an instance of the class
bloomfilter = BloomFilter(100,5)
# apply some method to instance...
bloomfilter.rand_inserts(15)
You would want to put main() outside the class:
class BloomFilter(object):
def __init__(self, numBits, numHashFunctions):
self.numBits = numBits
self.bitArray = [0] * numBits
self.hash = bloomFilterHash(numBits, numHashFunctions)
def insert(self, key):
def lookup(self, key):
def rand_inserts(self,num):
def main():
some_value = Bloomfilter(100, 5)
some_value.rand_inserts(15)
main()
I have a class file. Let's call it "C1.py". The sample code looks like below.
class C1(object):
def __init__(self):
self.greeting = "Hello, world!"
def M1(ans):
if ans == 1 or ans == 2:
return True
else:
return False
Now, I have another python file in the same folder, which will access the class file shown above.
from trial import C1
def getAns(class1):
while True:
ans = input("Answer: ")
if class1.M1(ans):
return ans
break
sample = C1()
print sample.greeting
ans = getAns(sample)
print ans
When I run those files, sample.greeting prints fine. Everything is fine until when the execution reaches the line "ans = getAns(C1)", which gives the error "M1() takes exactly 1 argument (2 given)".
So, where in the code should I change so that I can call that method successfully?
Note here that the above code is only the abstraction of my whole program to highlight my problem. It sounds stupid with just the code above alone. So, please, please bear with that for me.
M1 is currently defined as a method of C1, as such it needs to have an additional self argument which would be the instance of the class. I.e
class C1(object):
def __init__(self):
self.greeting = "Hello, world!"
def M1(self, ans):
if ans == 1 or ans == 2:
return True
else:
return False
In other languages such as C++ or Java the presence of self (or this) is implicit, but in python it's explicit.
alternatively if you don't want or need M1 to access C1's state you could make M1 static via #staticmethod i.e.
class C1(object):
def __init__(self):
self.greeting = "Hello, world!"
#staticmethod
def M1(ans):
if ans == 1 or ans == 2:
return True
else:
return False
How the below program execute my member A.fun without calling stackless.run() in the program?
import stackless
class A:
def __init__(self,name):
self.name = name
self.ch = stackless.channel()
stackless.tasklet(self.fun)()
def __call__(self,val):
self.ch.send(val)
def fun(self):
while 1:
v = self.ch.receive()
print "hi" , v
if __name__ == "__main__":
obj = A("sh")
obj(6)
output:
hi 6
I've never used stackless, but I'm guessing from the documentation that calling channel.send makes the scheduler call the other tasklet.
I have some python 3.4 code that works fine:
def run():
m = 0
while m != 1:
p = input('Please choose p: ')
p = makeInt(p)
#Some other code
print(p)
m = makeInt(input('Enter 1 if you would like to quit: '))
def makeInt(i):
try:
i = int(i)
except ValueError:
i = input('Incorrect input! Enter your answer: ')
i = makeInt(i)
return i
#Some other functions
if __name__ == '__main__':
run()
I want to put all this code in a class (Except possibly if __name__ ==...) When I put all the code including if __name__ ==... in a class like so:
class Foo(object):
def run(self):
m = 0
while m != 1:
p1 = input('Please choose p: ')
p1 = self.makeInt(p1)
#Some other code
print(p1)
m = self.makeInt(input('Enter 1 if you would like to quit: '))
def makeInt(self, i):
try:
i = int(i)
except ValueError:
i = input('Incorrect input! Enter your answer: ')
i = self.makeInt(i)
return i
#Some other functions and stuff
if __name__ == '__main__':
run()
I get the following error: TypeError: run() missing 1 required positional argument: 'self'. When I remove the self argument from run() it runs until makeInt() is called and then I get: NameError: name 'makeInt' is not defined. I get the same error if I take the if statement out of the class and call Foo.run(). I have some other code earlier in this program that works when I call functions of a class from another function in that same class. I realize I don't have to put all my code in a class, but in this case I want to. Why am I getting these errors and what can I do to put my working code in a class?
As others mentioned, by putting your functions in a class, you've made them methods, that means they need an instance of this class as first argument. So you can indeed call your run method using Foo().run() as Foo() will create an instance of Foo.
Another way (e.g. if you don't need the class for anything else than encapsulation) is to make them static, using the staticmethod decorator:
class Foo(object):
#staticmethod
def run():
...
#staticmethod
def makeInt(i):
...
if __name__ == '__main__':
Foo.run() # don't need an instance as run is static
In Python, a method can be static, i.e. no need for any special argument, a class method, i.e. first argument is the class itself, or a standard method, i.e. the first argument is an instance of the class.
Since you wrap your code within a class, your run() is a method now. You should remove your main from your class by unindenting it and initialize an instance of your class:
if __name__ == '__main__':
Foo().run()
It thinks the guard is a part of your class due to the indentation: you have your guard indented to the same level as the other class members. Unindent the
if __name__ == '__main__'
Also change it to be
if __name__ == '__main__':
main()
and then instantiate a new object of type Foo in your newly created main() function
def main():
newFoo = Foo()
newFoo.run()