use of variables in sets

[david smith]

I am a long-time user of ALPHA4 v6, and now I am considering updating to ALPA5. For that purpose I have downloaded a trial copy, and in the process of experimenting with it, I find that I am unable to use a variable in the Filter expression for any of the links to the various Tables in the Set that I have defined. From the Edit Set window, I defined a variable as global. Having done so, I was surprised to find out that the variable did not become listed in each of the Edit Structure windows for the various tables - so for each of those tables, I also defined the same variable as global. Having done that, I attempted to define filter expressions for the child tables.
The program accepted all the defined filter expressions; however, when I then viewed the Set, I found that all links resulted in in all linked fields being empty. I am positive that each child table does contain records for which the filters are "true", but they are not included in the view of the set. My syntax in the filter expressions for the variable (named ASOF) is "var->ASOF".
What am I doing wrong???/

[Ohlen Cartmell]

RE: use of variables in sets

When designing your links, have you already assigned a value to the variable. Your links will not be active until a value is assigned.

[Ken L Herrold]

RE: use of variables in sets

David;

Ohlen is right and you, of course know that using a variable based filter would require the variable to have a value. If that global variable is character, you can set its value thus ASOF="your value". The filters will then work.

Remember A4 when you declared a variable with a 'Set' statement, it would remain there for the entire alpha boot. The values could be overwritten, but that variable still existed until you closed the program. It's always been comforting to me to see the current value of any variable in A4 by pressing '[ALT][F3]V'. I know others have different methods but this one suits me because it is what I'm used to from A4. This method simulates, somewhat, the A4 regimen.

I declare a bunch of global variables on the 'Oninit' event of my first Menu. Some have values and some don't. If I need to either change one of the values or assign a value, I use a prompt at the time of need - just like A4, and assign it.

A quick way to check current global variables' values, is to select from the Alpha Main Toolbar/'View' then 'Code Editor' -Xbasic Explorer and open the 'Variables' tree.

IMPORTANT: When you do select 'Code Editor' that 'View' drop menu changes displaying 'Xbasic Explorer' -That MUST be checked to display to display the Explorer. I didn't realize this and couldn't find my friendly variables anywhere once. It was then that I discovered this [maybe nebulous] feature.

Watch for it. At times I would get everything up with the 'Code Editor' selection; close the Xbasic explorer with its windows' 'X' [leaving the code editor still visible]; then the next time Explorer wouldn't open simultaneously with the code editor. It was then that I observed the Drop Menu change and the need now for a check on the Explorer.

Just some thought from a recent newbie to a newer newbie.

Ken

[david smith]

RE: use of variables in sets

Ohlen:

Thank you very much for your reply.

In answer to your question, I knew the variable needs a value, and thought I had done so when I used the "default value" option on the "variable" section of the "Set definition" window. Evidently, that really doesn't assign the entered value whenever the user doesn't assign some other value. That, of course, raises the next question - when, if ever, is that assigned "default" value really used.

However, it now doesn't make any difference - because I now find that the time limit on my trial copy of Alpha 5 has expired, without having given me any advanced notice. Now I really don't know whether or not I want to buy a copy. The reason I am hesitant is that I find the documentation ("books" and on-line "Help") that came with my trial copy were totally inadequate - since I was unable to find in any of it how I might assign a variable value that will work in filter statements.

[david smith]

RE: use of variables in sets

Ken:

As I told ohlen,
"Thank you very much for your reply.

In answer to your question, I knew the variable needs a value, and thought I had done so when I used the "default value" option on the "variable" section of the "Set definition" window. Evidently, that really doesn't assign the entered value whenever the user doesn't assign some other value. That, of course, raises the next question - when, if ever, is that assigned "default" value really used.

However, it now doesn't make any difference - because I now find that the time limit on my trial copy of Alpha 5 has expired, without having given me any advanced notice. Now I really don't know whether or not I want to buy a copy. The reason I am hesitant is that I find the documentation ("books" and on-line "Help") that came with my trial copy were totally inadequate - since I was unable to find in any of it how I might assign a variable value that will work in filter statements."

Did you, per chance, receive any "hard copy" documentation, similar to the excellent manuals I received for Alpha 4 v6 ?? I know that the company offers to sell to books by a supposed independant author, but the cost of them is more that 50% more over the program price - which irks the heck out of me if they are the only way I can get decent documentation.

[Peter.Greulich]

RE: use of variables in sets

>>That, of course, raises the next question - when, if ever, is that assigned "default" value really used.>since I was unable to find in any of it how I might assign a variable value that will work in filter statements.ASOF="your value" should work. This is standard stuff that Alpha handles w/o problems. It should work for you too. You just need someone to walk you through it. Perhaps you can uninstall Alpha and reinsatll? If that doesn't work can you download another trial version? Where there is a will, there is a way. Alpha Five is a great product, believe it or not.

[david smith]

RE: use of variables in sets

Peter

Thanks for your comments. I believe the downloaded file for the trial copy deleted itself, or maybe I lost it. Since the site for donwloading it asked for my E-mail address, I suspect they won't allow me to downlosd another, but I admit I haven't tried.

As to defining my variable:

1) The default value I tried, and need for my intended purposes involved an expression rather than a simple value. I am positive that it didn't work, since I then used the method that Ken suggested for checking values of variables - my variable was there but it had a null value. I also tried using just a fixed value in the definition of the filter, and that DID work. I had planned, for exploratory purposes, to try assigning a fixed value for the variable and then using that in the filter definition. Unfortunately, my trial time expired before I did it.

2) I am aware of the statement for assigning a value to a variable, using the statement you mentioned. My problem was that I was unable to find, in any of the documentation available to me, just where and how I could enter that statement into my database.

[Peter.Greulich]

RE: use of variables in sets

David,
If you were entering an expression in the default value variable dialog box, that won't/can't work. Expressions always work in expression boxes (where all the functions are available to you by drag'n'drop or double clicking) or in the xbasic code editor.

As far as documentation goes, many of us have complained that it is less than desirable. But this board goes a long way in making up the difference. FWIW. I believe A5 v.5 will have more/better documentation as well as a new book to be released at the same time as v.5 by Peter Wayne.

There is a learning curve for sure, and it is not to be minimized, but hang in there. You may likely find that it was worth the effort.
Peter

[david smith]

RE: use of variables in sets

peter

Thanks. For now, I think I will wait for version 5 before I finally decide whether or not to switch from ALPHA 4 to ALPHA 5.