Dot variables

[John Marrone]

Hi
Can someone explain dot variables. Are these created on the fly and you just add properties at will. Can you dim them or assign pointers to them. I have been programming in vb6 and I can not get my brain to grasp these type of variables. In the manual it looks like you create them on the fly and you add properties to them on the fly. Any help in understanding them would be helpful.

Thanks
John Marrone

P.S. I hopr within a few days I will have less questions to bother you folks with. I am really thankful for the help all of you have given so far.

[Stan Mathews]

RE: Dot variables

Take a look here first. Then you might want to post more specific questions.

[John Marrone]

RE: Dot variables

Thanks Stan, that ws a very good article. What it didn't cover was if you can create one on the fly. But I have in the Interactive window so I would say you can.

Also I read in an article that Alpha 5 does not have multi deminsional arrays. Will I be able to do this:

Type RaceRecord
Date as c
Race as c
Track as c
End Type

Dim RC(100) as RaceRecord

And then use it like this:

tbl.Date = RC(1).Date
tbl.Race = RC(1).Race
tbl.Track = RC(1).Track

and so forth.

If I can this would solve all my problems with not having multi deminsional arrays.

[Stan Mathews]

RE: Dot variables

I read the syntax as

Dim RC[100] as {RaceRecord}

Then I'm not sure whether you mean

tbl.Date = RC(1).Date
tbl.Race = RC(1).Race
tbl.Track = RC(1).Track
this fills table fields with the array values, assuming you have populated the array

or

RC(1).Date = tbl.Date
RC(1).Race = tbl.Race
RC(1).Track =tbl.Track
this assigns record values to the array elements.

Either set of statements could be valid bsed on context and other statements, such as putting the table in enter or change mode before "tbl.Date = RC(1).Date".

[John Marrone]

RE: Dot variables

I think your answer was yes. Sorry to confuse you I see now that A5 uses "[]" for arrays. But I create a type variable and I can then create variables of that type like this:

Dim MyVar[100] as RaceRecord ??

Does RaceRecord have to be enclosed in "{}" and is this the rule anytime you dim a variable with a User Define Ttype, so I should do it like this:

Dim MyVar[100] as {RaceRecord}

I quess what I am asking is if the curly brackets are required. If I can do what I need to do like this it is even better than having multi deminsional arrays.

John

[Stan Mathews]

RE: Dot variables

I think my answer was yes, as well.

I'm trying to lend a hand here, but probably not giving you what you want. I've never used the features you are inquiring about, just somewhat familiar with the docs. The following is cut and paste from the documentation

' Declaring Variables Using a Structure
' Define the structure.
type customer
name as C
company as C
phone as C
age as N
end type

dim custs[10] as {customer}
? properties_enum(custs[1] )

= "NAME
COMPANY
PHONE
AGE
"

So it seems the curlies are required.

[Jim Chapman]

RE: Dot variables

Hello John,

Check out the Type.... End Type in the documentation. Basically you are creating a pointer, which can have many subelements (variables) of different type. Really just a cleaner way to define dot variables. Also check out collections.

As to multi-dimensional arrays, unless our definitions are different, Alpha certainly has this capability, ie: the above Type...End Type command.

Good luck,

Jim

[Blake]

RE: Dot variables

You can also skip the array syntax entirely, if you wish. It's somewhat more cumbersome to evaluate, but somewhat more flexible as far as range. And since there's little serious type-checking in A5 and you're using all character fields, you could just as well do it this way:

A.1.Race = "5th"
A.1.Date = today
A.1.Track = "Santa Anita"

You can use a variable to index this pseudo-array:

eval("A."+N+".Race") = "5th"
eval("A."+N+".Date") = today

If you do this sort of thing a lot, you could make a function:

ASet("A", N, "Race", "5th")

or even:

ASet(N, "Race", "5th")

if you were working with a single pointer variable or one that you changed infrequently, and so could use a global.

I find having to set array limits to fixed values to be a bit of a pain, so I usually opt for using pointer variables.