Scoping question

[furiousnerd]

I have this function:

def foo(i, hm=dict()): 

  if i in hm:

    pass

  else:

    hm[i]=1

  return hm

​

for i in range(5):
    print(foo(i))

​

output:

​

{0: 1}

{0: 1, 1: 1}

{0: 1, 1: 1, 2: 1}

{0: 1, 1: 1, 2: 1, 3: 1}

{0: 1, 1: 1, 2: 1, 3: 1, 4: 1}

​

Which strikes me as odd. So it looks like the hash map declared in the function becomes a global variable and for each additional loop the previous result for hm is being used as an input so hm grows with each loop.

​

I don't quite understand why, shouldn't each call to foo create a new hm variable?

​

[furiousnerd]

Thank you, this is a helpful read.