Deleting all elements from a table

[Nick Gammon <nick@...>]

My apologies if this has been answered, couldn't see a specific  
reference to it.


I want to delete all elements from a table (any sort of keys, not  
just numeric).

However I don't want to just to do this:

t = {}  -- make fresh, empty table


The reason for that is some of my sub-modules may have stored the  
reference to the table in a local variable, creating a new table  
won't empty those out. The original table needs to have its entries  
removed.


Is this OK?

t = { a = 1, b = 2, c = 3, 4 = 4}

for k in pairs (t) do
  t [k] = nil
end -- for


It *seems* to work however I seem to recall that you aren't supposed  
to change keys during a table traversal (like, doing a "tostring" on  
them). However does deleting a key count as changing it?

Or, do I need to create a second table with all the keys in it, and  
traverse the second table, deleting elements from the first table,  
and then remove the second table? Sounds like a messier way of doing it.

- Nick