Variable declaration?

[Tim Kiebert]

Re: Variable declaration?

Okay, so I have a button on a form that starts off a data collection process. One of the first things that happens is that several SHARED variables are DIMmed and then assigned values (mostly logical False, but a few are blank character vars).

Three or four forms are called. Each one, in its INIT event, DIMs those shared variables again so that they can be used by the form. (I collect data to variables rather than directly enter data into a table in order to check the data and for other manipulation prior to placing the information into the record.)

My question is this: I originally used fields copied from a form that IS directly accessing/showing the data, and converted the source from a table/field to a variable. But it seems that the form doesn't see the variables that I DIMmed in the INIT event.

I have to create a "new" variable rather than assign an existing one to the data object. Am I doing something wrong?

......
These are also DIMmed in the OnPush event of the button that, among other things, calls the form in question.

I want to use these variables in the Field property of several check boxes on the form. However, when I go to choose them they are not listed as available variables. I have to enter them again as new variables. I know I'm doing something wrong, I just can't figure out what that something is.

It seems like this thread is heading into the subject of when a variable is available to share its data.

However the original question seems to be more along the lines of having access to the variable in design mode of the form.

Declaring a variable of any scope in any event of a form will not make it available to the form in design mode.(the exception is if you have declared it as global, try to run the form and then put it back into design mode.

If you want a bunch of variables available in your form then yes you need to create them in the variable-defining-thing-a-majiggy found by using the large 'V' toolbar button (when choosing new variable from the objects property dialog you get a different looking thing-a-mjiggy but the vars are defined in the same place)

You will probably have more questions but hopefully this gets you to the next step. :)

This is a good page on variables and scope
Be sure to check out the See Also links at the bottom of the page.

Mike. I think that page might be at odds with your thoughts on shared variables between forms.

[MikeC]

Re: Variable declaration?

Hi Tim,
I don't see it that way---the boxes there all seem to be same as my analogy in how I see it. I know what I stated is simplistic but has gotten me quite far in the actual way in which variable scoping works....that was my intention basically--to have something simple that will help lead others to understanding more about scope.

Once the simplistic idea is understood, then when checking out Peter Wayne's and Ira Perlow's tips on variables, their more advanced concepts/thoughts will make much more sense. I know that prior to thinking of variables with this and other analogies and understanding the basic concepts that they instill, both Peter's and Ira's explanations went over my head very quickly. :D (yeah, I know...really setting myself up here for your amusement haven't I! :D )

[csda1]

Re: Variable declaration?

Hi Mike, et al,

Once the simplistic idea is understood, then when checking out Peter Wayne's and Ira Perlow's tips on variables, their more advanced concepts/thoughts will make much more sense.

As it turns out, no matter what the scope of a variable is, you can use that variable if you have a pointer to it (which is like having a secret, direct microphone/speaker in the office or area that you can hear/speak IOW, read/write). The variable scopes of Alpha allow you to access the items at the same scope without prefacing them with pointers as a prefix. If DIM'd in the current code, it will use that scope for that dim'd variable rather than the default one of local. Without a DIM, it will search for a matching name 1st at Local, then Shared (Session), then Global and use the 1st one it finds. A layout like a form or browse runs in it's own session (same as thread), and has it's own unique shared space. If you preface variable references with pointers to other variable spaces, then you can read and write to those spaces directly.

Just to confuse you further, a variable pointer can be a pointer to any variable space, but the scope of the pointer variable doesn't have to be the same (and in fact, ideally, as most variables, should be local). For those who haven't read it, see my tips page on variable scope.