Closures and Loops in Python

Question

Suppose I have the following code

callbacks = []
for i in range(10):
    callbacks.append(lambda x: i)

all functions in callbacks will return the final value of i. How can I create callbacks that return the current value for i at creation time?

Asked By: duckworthd

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Source

Answer 1

for i in range(10):
  callbacks.append(lambda x = i : x)

Answered By: gefei

Answer 2

In [113]: callbacks=[]

In [114]: for i in range(10):
    callbacks.append(lambda x=i:x**2)
   .....:     
   .....:     

In [117]: callbacks[0]()
Out[117]: 0

In [118]: callbacks[1]()
Out[118]: 1

In [119]: callbacks[2]()
Out[119]: 4

In [120]: callbacks[4]()
Out[120]: 16

Answered By: Ashwini Chaudhary

Closures and Loops in Python

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