When is del useful in python?

Question

I can\'t really think of any reason why python needs the del keyword (and most languages seem to not have a similar keyword). For instance, rather than deletin

Answer 1

To add a few points to above answers: del x

Definition of x indicates r -> o (a reference r pointing to an object o) but del x changes r rather than o. It is an operation on the reference (pointer) to object rather than the object associated with x. Distinguishing between r and o is key here.

• It removes it from locals().
• Removes it from globals() if x belongs there.
• Removes it from the stack frame (removes the reference physically from it, but the object itself resides in object pool and not in the stack frame).
• Removes it from the current scope. It is very useful to limit the span of definition of a local variable, which otherwise can cause problems.
• It is more about declaration of the name rather than definition of content.
• It affects where x belongs to, not where x points to. The only physical change in memory is this. For example if x is in a dictionary or list, it (as a reference) is removed from there(and not necessarily from the object pool). In this example, the dictionary it belongs is the stack frame (locals()), which overlaps with globals().