Where can I find a description of all the special variables such as "A_Field_Value". I can not find an explanation of "A_deleting_record" anywhere.
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RE: Special Variables
The A_deleting_record variable was added after the initial release. It's documented in the Xbasic Reference.PDF file - page 969 in my copy.
Here are the ones that I have in my list starting with "A_". Of course, there are many others with specific uses such as ui_ok_cancel, File_RO_Shared, etc.
These are also listed in the Xbasic Reference.chm file under "System Variables". (Since the first one is really only applicable to v1 programs or converted v1 programs, it's probably no longer officially supported.)
A_app_current_path (v1 - applies to Card Stacks only.)
A_can_do (The preferred method now is to use the cancel() command)
A_db_current
A_db_current_path
A_deleting_record
A_field_value
A_form_current
Most of these were available in version 4 - or earlier. If anybody can think of others, please post them here and I'm sure Ed will add them to the Help file - along with the A_deleting_record variable. Hint, hint!
By the way Ed, if you read this, thanks for adding my descriptive text to the A_db_current_path info. I hope it will save some time and trouble for other users.
From the PDF file:
The A_DELETING_RECORD Variable - Useful in Change and Save Events
To Alpha Five, changing the value in a field, and deleting a record, are both changes to the current record,
and both actions trigger the Change and Save record events. This makes it impossible to distinguish
between an effort by the user to change a record, or delete the current record. The reason for this is that a
record is "deleted" by changing the value in a special "hidden" field in the record.
The A_DELETING_RECORD variable allows you to distinguish between deleting and changing a value in a field. A_DELETING_RECORD is set to .T. during a record delete, and to .F. when the record is being edited.
With this variable, you can write scripts that do something when the user makes a change to a field value, but not when they delete the record.
For example, the following OnChange event script shows how you would use the variable:
if .not. A_DELETING_RECORD then
'....perform actions normally associated with a record change
end if
Cal's note: I'd use:
IF A_deleting_record
END
END IF
and, put the rest of the code afterward - but that's just personal preference. -
RE: Special Variables
Hmmm, I though it was created after the initial release but now I'm not sure because I couldn't find it in the release notes.Comment
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RE: Special Variables
Cal,
Thanks for your reply. When I was working with the examples on Page 121, figure 14-8 in Peter Wayne's Application Programming With XBasic In Alpha Five, I noticed how he would handle a deleted record. In his checkbook rebalancing scheme, he still needs to rebalance after the record is deleted. He does this by forcing the user to change an amount to zero and not allowing a delete unless it is zero. This change causes the checkbook to be rebalanced before the delete. When the delete takes place there is not need for a rebalance. I discovered that the record is still there during the "on save" event that follows a delete. The rebalancing logic requires that the rebalancing start with a date prior to the date of the record being deleted. If it is determined that a delete is taking place the date from the deleted record is available to be saved. Then if the table is indexed by date and a new file pointer is established with a (tbl)=table.open a fetch_find with the saved deleted date will find a record with an earlier date and the find will not include the deleted record. This works if one can count on the record being there initially and then not there when the file is indexed by date. My code is included below. It works as long as I can counnt the deleted record hanging around to the on-save event and not being included in the fetch_find.
im this_rec as n
dim tbl2 as p
dim bal as n
dim amt as n
dim shared old_date as d
dim current_date as d
dim rebalance_date as d
dim this_tbl as p
debug(1)
this_tbl=table.get("mycheckbook")
Current_date=this_tbl.date
select
case a_deleting_record=.t.
rebalance_date=current_date
case old_date={}
rebalance_date=current_date
case old_dateComment
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RE: Special Variables
Take a look at the index after going to the Programming Reference webhelp at http://support.alphasoftware.com/xbasic_reference/index.htmComment
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