Why do they enclose code within "useless" do statements?

[Duugu]

While reviewing code I sometimes come across things like

do 
	function testfunction()
		--stuff
	end
end

Everytime I saw this I asked myself what this may be good for.
Why these useless do statements?

Could someone please enlight me? Thank you very much.

[Seerah]

Because they're not useless. A do block can limit scope just as a function or if statement can.

http://www.lua.org/pil/4.2.html

[Rilgamon]

http://lua-users.org/wiki/ScopeTutorial

[Duugu]

Oke. That sounds logical. Thank you very much.

But ... shouldn't it be

do 
	local function testfunction()
		--stuff
	end
end

instead of

do 
	function testfunction()
		--stuff
	end
end

?

Isn't the version without the global function the same as without the do/end??

[Seerah]

A global variable is a global variable. But the local function is only valid for that do block. (ie, you could have another variable of the same name elsewhere)

/edit: unless I'm showing my noviceness here

[NitraMo]

Based on my limited lua knowledge, if there only is:

do
  function fn()
    -- Yeah, whatever here...
  end
end

Then the do should be useless, as the OP is pointing out, unless there is something magical done then. The do is just wrapping the function and the do scope will contain nothing as fn() is global.
Anyone know this?

[Torhal]

Here's an example:

local MyComplexFunction
do
	local count = 0

	function MyComplexFunction() 
		count = count + 1
		print(("MyComplexFunction was called %d times!"):format(count))
	end
end

Since MyComplexFunction was previously declared as a file-local variable, the definition within the do-block is now assigned to it. Had I prepended the definition within the do-block with the "local" keyword, then the function would have become a new variable which was only in scope within the do-block. Had I not declared the file-scope variable before the do-block definition, MyComplexFunction would have been declared and defined within the global environment table.

Using this mechanism, I can be sure that the variable "count" is only ever used for the implementation of MyComplexFunction, and can not be altered elsewhere.

[Nobgul]

I may be showing my noviceness, and or lack of understanding of the OP point but. Also incoming text crit =P

Err brain fart. but something like....

If Nobgul = isin $1 then
function Send_hello()
------stuff here.
else do
function You_Are_Not_The_One()
------stuff here.
 
end 
end

I could have swore the "do" was just there to tell the command to fire. I am pretty sure that is the way it is in C++ anyway. meaning that the do command will always fire and the rest of the function will continue to work its self out. where if you used just a else then only 1 or the other would fire.

if Nobgul == isin $1 then do
 
function savename() then
-----something here
 
function ParseNameAndIssueCommand
-------- suff here

Basically what i am getting at is using the statment to
grab a name in chat
make sure the name matches a specific name, either way save the name
then if the name does match then issue the command or w/e
otherwise take the saved name and pass a diff command

else do
then do
etc..

Because there is also
do while


Anyway I think there may not be a need for it.

[Torhal]

Originally Posted by nobgul <snip> Anyway I think there may not be a need for it.

Did you even read what I posted? :P

[Nobgul]

you posted before me and i didn't refresh the page lol.

[Torhal]

Originally Posted by nobgul you posted before me and i didn't refresh the page lol.

D'oh! It all makes sense now!

[Duugu]

It's clear now. Thank's to everyone.

[Mischback]

*cough*

Sometimes... sometimes I simply add a "do ... end"-block to some code, just because that enables Notepad++ to collapse that block. Dirrrty hack there, I know, but since it won't hurt nobody...