Enum and Union

[AsianSensation]

I'm having trouble understanding enum and union syntax, what do they do, and how do I use them efficently?

[Dan]

well the enum things is a litte odd in turing.

here is an expale i made to output colors:

code:

type colors : enum (red, green, blue, black, white, lightGreen, lightBlue, lightRed) var c : colors := colors.red put c for i : 1 .. 7     c := succ (c)     put c end for

honstety i dont realy see the point of them, in most progames this whould be realy needed. (can do same thing esaer with an array of strings).

As for union:

turing doc's say this about them:

A union type (also called a variant record) is like a record in which there is a run time choice among sets of accessible fields. This choice is made by the tag statement, which deletes the current set of fields and activates a new set.

basicly they have to do with recoreds, i dont know much about them since i have never used them in turing.

[AsianSensation]

I just wanted to check on this union thing, because I was reading a tutorial somewhere, here, http://www.doc.ic.ac.uk/lab/firstyear/turing_lecture_notes/turing_lecture_9.html to be exact, and it says that union could be used to simulate polymorphism.

Except the example was to confusing, hopefully someone will explain it to me.

[Catalyst]

u dont have to simulate polymorphism in turing
it can be implemented using the deferred key word

[rizzix]

well technincally the union is not used too often in the mordern world.
it was used in the past, since at that time memory was an issue.

a union lets u declare different variables to use a common memory area. well at least thats what a union means in c