Python modify list while being iterated

Content:

Just saw a post on LinkedIn warning against in Python modifying a list while iterating over it.

Good advice: the results of doing so are indeed surprising to the inexperienced.

Example:

items = [ 1, 2, 2, 3, 4 ]
for item in items:
    if item == 2:
        items.remove(item)
print(items)

[1, 2, 3, 4]

Java and C# throw an exception in such cases.

package september;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class UpdItList {
    public static void main(String[] args) {
        List<Integer> items = new ArrayList<Integer>(Arrays.asList(1, 2, 2, 3, 4 ));
        for(Integer item : items) {
            if(item == 2) {
                items.remove(item);
            }
        }
        System.out.println(items);
    }
}

Exception in thread "main" java.util.ConcurrentModificationException
    at java.base/java.util.ArrayList$Itr.checkForComodification(ArrayList.java:1013)
    at java.base/java.util.ArrayList$Itr.next(ArrayList.java:967)
    at september.UpdItList.main(UpdItList.java:10)

using System;
using System.Collections.Generic;

namespace UpdItList
{
    public class Program
    {
        public static void Main(string[] args)
        {
            IList<int> items = new List<int> { 1, 2, 2, 3, 4 };
            foreach(int item in items)
            {
                if(item == 2) 
                {
                    items.Remove(item);
                }
            }
            Console.WriteLine(string.Join(",", items));
            Console.ReadKey();
        }
    }
}

System.InvalidOperationException: Collection was modified; enumeration operation may not execute.

   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at UpdItList.Program.Main(String[] args) in c:\IDEProjects\SharpDevelop5\UpdItList\UpdItList\Program.cs:line 11

I very much prefer the exception.

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