I wanted to know if is safe ( documented behaviour? ) to delete the domain space of an iterator in execution in Python.
Consider the code:
import os
import sys
sampleSpace = [ x*x for x in range( 7 ) ]
print sampleSpace
for dx in sampleSpace:
print str( dx )
if dx == 1:
del sampleSpace[ 1 ]
del sampleSpace[ 3 ]
elif dx == 25:
del sampleSpace[ -1 ]
print sampleSpace
'sampleSpace' is what I call 'the domain space of an iterator' ( if there is a more appropriate word/phrase, lemme know ).
What I am doing is deleting values from it while the iterator 'dx' is running through it.
Here is what I expect from the code :
Iteration versus element being pointed to (*):
0: [*0, 1, 4, 9, 16, 25, 36]
1: [0, *1, 4, 9, 16, 25, 36] ( delete 2nd and 5th element after this iteration )
2: [0, 4, *9, 25, 36]
3: [0, 4, 9, *25, 36] ( delete -1th element after this iteration )
4: [0, 4, 9, 25*] ( as the iterator points to nothing/end of list, the loop terminates )
.. and here is what I get:
[0, 1, 4, 9, 16, 25, 36]
0
1
9
25
[0, 4, 9, 25]
As you can see - what I expect is what I get - which is contrary to the behaviour I have had from other languages in such a scenario.
Hence - I wanted to ask you if there is some rule like "the iterator becomes invalid if you mutate its space during iteration" in Python?
Is it safe ( documented behaviour? ) in Python to do stuff like this?
