Re: Removing while iterating through table

[Jack Christensen <jack@...>]

It seems that assigning nil to a non-existant entry 'can' cause an error.

Try the following code:

list = { a = 1, b = 2, c = 3, d = 4, e = 5, f = 6 }

for k, v in pairs( list ) do
    print( "key: " .. k .. " value: " .. v )
    list[ k ] = nil
    list[ "some key" ] = nil
end

I get an invalid key for 'next' error everytime. But interestingly enough, merely change "some key" to "some non-existant key" and it doesn't crash.

I have not been able to reproduce a crash where setting an existant key caused an error (yet?).

Jack



Wim Couwenberg wrote:

Is this 'official'?
    

Yes, I think.  :-)  At least the manual only states
that assigning to a *non-existent* key in a table
results in undefined behaviour during traversal. (See
the entry for `next').

Assigning nil to *any* key (existing or not) is also
OK, though I'm not sure if tbis is `official' or only
documented by ltable.c ...  :-)

--
Wim



	
		
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