Flexible Arrays in Procedures

[Silinter]

Alright, here is my problem, nice and short.
I want a procedure to take in a flexible array and change it; i.e.

Turing:

procedure doThis (var arrayToUse : flexible array 1 .. * of int)     new arrayToUse, 1 end doThis

however, it gives me a syntax error. Does Turing support taking in flexible arrays in procedures?

[richcash]

I don't believe so, but someone else may be able to confirm this as a fact.

You may already know that you can pass a flexible array as an argument if the parameter is a static array with an unknown upper bounds, but then during the procedure it will be treated as a static array.

code:

proc f (arr : array 1 .. * of int) end f var x : flexible array 1 .. 3 of int f (x)

But again, I'm not sure of how to change bounds of an array during a procedure. You could accomplish this by creating your own array class.

What is the situation you need this for? There may be an alternative.

[Silinter]

I wanted to create a procedure to take out elements from a flexible array, so I just thought it'd be easier if I made it into a procedure.
Now what's all this talk about "array class"?

[richcash]

Yeah, I don't think that can be done in turing. Unfortunately, you can't make a procedure to remove an element from an array.


But, you can make a class that represents a flexible array and solve most if not all limitations associated with flexible arrays in turing. Like this, for example :

code:

class Array     export ini, add, remove_element, value_at     var arr : flexible array 1 .. 0 of int     proc ini (arr_ : array 1 .. * of int)         new arr, upper (arr_)         for i : 1 .. upper (arr)             arr (i) := arr_ (i)         end for     end ini     proc add (n : int)         new arr, upper (arr) + 1         arr (upper (arr)) := n     end add     proc remove_element (n : int)         for i : n .. upper (arr) - 1             arr (i) := arr (i + 1)         end for         new arr, upper (arr) - 1     end remove_element     fcn value_at (n : int) : int         result arr (n)     end value_at end Array

You can pass an Array object as a parameter to a function, and with more methods than in my poor example, get the full functionality of a flexible array. Notice that now you don't need to make a procedure that removes an element because you can just make a method that does it for you.