OpenEuphoria

Re: A better way to do this?

• Posted by Alexander Toresson <alexander.toresson at gmail.com> Feb 26, 2005
• 446 views

Brent W. Hughes wrote:
> Consider the following code which does not do what I want:
> --****************************************
> procedure Sub2(sequence MyList)
> 	MyList[900] = 5
> end procedure
> -----------------------------------------
> procedure Sub1()
> sequence List
> 	List = repeat(0,10000)
> 	Sub2(List)
> 	-- Here, I would like List[900] to be 5.
> 	-- But, of course, it's not; it's 0.
> end procedure
> ------------------------------------------
> Sub1()
> --****************************************
> I really wanted Sub2 to change the 900th element of List.
> Here are a couple of solutions that I don't like:
> --****************************************
> function Sub2(sequence MyList)
> 	MyList[900] = 5
> 	return MyList
> end function
> -----------------------------------------
> procedure Sub1()
> sequence List
> 	List = repeat(0,10000)
> 	List = Sub2(List)
> end procedure
> ------------------------------------------
> Sub1()
> --****************************************
> This has to copy 10000 elements to make one little change.
> Here's the other solution:
> --****************************************
> sequence List
> ------------------------------------------
> procedure Sub2()
> 	List[900] = 5
> end procedure
> ------------------------------------------
> procedure Sub1()
> 	List = repeat(0,10000)
> 	Sub2()
> end procedure
> ------------------------------------------
> Sub1()
> --****************************************
> I don't really like giving List such a wide scope in this way.
> 
> Is there another, more elegant, solution to this problem?
> 

Unfortunately, no. I've also noticed the problem. If you could do
pass-by-reference in euphoria, this would have been solved.

I used the same solution as you in an app of mine, however,
I had 6 big sequences. This means I had to duplicate the *same*
code 6 times, and I had to fix bugs 6 times, add features 6 times
etc, which was *very* unelegant. However, this sped up the program
by at least 100x. So if pass-by-reference would be implemented,
we'd get this advantage without this ugly hack.

Regards, Alexander Toresson