Playing "tricks" with strings

[sgerber]

I inherited some coding that used to work in an old version of Alpha. Can someone tell me if/how this is implemented today.

A string variable contains values to be used in an expression. Let's call the string variable CONTAINER. There are two fields FLD1 and FLD2 which will eventually be used in an expression.

DIM GLOBAL CONTAINER AS C

At some point in the logic we have set CONTAINER = "FLD1<\"2\".AND.FLD2>\"6\""

Our expression requires us to have FLD1 <"2" .AND. FLD2 >"6" as tests.

How do we remove these field tests from the string variable that has them "trapped"? In Alpha 1 the following actually works: QCNT2>=VAR->VCNT2.OR.QVAL2>=VAR->VTOT2).AND." + CONTAINER + "

Sometimes in version 11 this syntax works and sometimes it seems to throw invalid expression errors. Any thoughts about how to handle this?

Thanks ... Sam

[Stan Mathews]

Re: Playing &quot;tricks&quot; with strings

Sometimes in version 11 this syntax works and sometimes it seems to throw invalid expression errors.

As I suggested to you earlier....

Whether or not the value of a variable is available has everything to do with the scope of the variable. If you

dim vcnt2 as N
vcnt2 = 7

and then reference the variable in another script, it will not have a value or be known.

In many instances Alpha will try to resolve shared and global variables in a filter string but you should strive to avoid having to.

Instead of

"state = var->ste"

you should use

"state = "+quote(var->state)

[sgerber]

Re: Playing &quot;tricks&quot; with strings

Whether or not the value of a variable is available has everything to do with the scope of the variable. If you

dim vcnt2 as N
vcnt2 = 7

Stan, I DIM all variables as GLOBAL so they'll pass between scripts and forms, reports, etc. Did you think I wasn't?

In many instances Alpha will try to resolve shared and global variables in a filter string but you should strive to avoid having to.

Instead of
"state = var->ste"
you should use
"state = "+quote(var->state)

Sorry but I don't understand this. I guess I'm a bit dense right now but I'm not getting the point.

[Stan Mathews]

Re: Playing &quot;tricks&quot; with strings

A quoted string is literal text.

"state = var->ste"
this is essentially no different than
"state = Maine"

Built into Alpha is functionality that will attempt to substitute the value of a variable into a quoted string in place of the variable name. That functionality is not perfect and does not apply to local variables.

You can be a hero and assist Alpha when you want that variable substitution leaving nothing to be interpreted.

"state = "+quote(var->ste)
This statement says take the quoted character string "state = " and concatenate the current value, quoted, of the variable ste.

Try it in the interactive window where the auto substitution does not work.

dim global ste as C
ste = "Maine"

? "state = var->ste"
= "state = var->ste"

? "state = "+quote(var->ste)
= state = "Maine"

[sgerber]

Re: Playing &quot;tricks&quot; with strings

Stan, I'll bet you're tired of me by now. If you are then please just ignore this post.

I just spent more than an hour in the "Interactive Window" All I really seem to have proved is that I can't use your technique which returns a string from the character variable. The string doesn't work inside a filter expression. I further proved that the old Alpha Five V1 syntax for the variable works fine in the interactive window, as it did in the Operations Genie. It just doesn't seem to work in Report or Label record filters. Here's part of my session in the interactive window:

dim global vconmag as C
vconmag = "CONLON<\"2\".AND.MAGIC<\"2\""

? "result="+quote(var->vconmag)
= result="CONLON<\"2\".AND.MAGIC<\"2\""

? vconmag
= CONLON<"2".AND.MAGIC<"2"

? ".NOT.DELETED().AND.PSW=\"2\".OR.(.NOT.(PSW=\"0\").AND.QLDATE>=VAR->VLDATE.OR.QCNT1>=VAR->VCNT1.OR.QVAL1>=VAR->VTOT1.OR.QCNT2>=VAR->VCNT2.OR.QVAL2>=VAR->VTOT2)"
= .NOT.DELETED().AND.PSW="2".OR.(.NOT.(PSW="0").AND.QLDATE>=VAR->VLDATE.OR.QCNT1>=VAR->VCNT1.OR.QVAL1>=VAR->VTOT1.OR.QCNT2>=VAR->VCNT2.OR.QVAL2>=VAR->VTOT2)

? ".NOT.DELETED().AND.(PSW=\"2\".OR.(.NOT.(PSW=\"0\").AND.QLDATE>=VAR->VLDATE.OR.QCNT1>=VAR->VCNT1.OR.QVAL1>=VAR->VTOT1.OR.QCNT2>=VAR->VCNT2.OR.QVAL2>=VAR->VTOT2).AND."+ VCONMAG +""
= .NOT.DELETED().AND.(PSW="2".OR.(.NOT.(PSW="0").AND.QLDATE>=VAR->VLDATE.OR.QCNT1>=VAR->VCNT1.OR.QVAL1>=VAR->VTOT1.OR.QCNT2>=VAR->VCNT2.OR.QVAL2>=VAR->VTOT2).AND.CONLON<"2".AND.MAGIC<"2"

I DIMmed my real life variable and set it to values exactly as my script does. The first thing you'll see is that your +quote returns unresolved characters \"2\" and the extra syntax of result=.

The next thing you'll see is that simply entering the character variable returns its contents without quotes and with the escape characters resolved. That's exactly what I want because it will work in a filter expression.

The next item is my real life filter expression without the troublesome vconmag variable and then you'll see my complete filter, including vconmag. You'll see that the 17 year old Alpha V1 syntax works like a charm in the filter.

Why it's problematic in some layout record filters is beyond me. I also cannot seem to obtain approval from the Alphaholics that it's OK sometimes to use things that worked in Version 1, although clearly the Alphaholics make fun of me for sticking with some of the things I learned in 1996. I've even had one person suggest I forget everything I ever knew about V1 and start over. Stan, that's crap and if I had done that I'd be nowhere converting my application, despite your very good nature and all the assistance I've received from you here.

I'll stop ranting and just leave you with the result of my session in the interactive window.

Also, Stan I still cannot get Alpha to save my query, as a query, so that the Label and Reports can specify it as such. I'll eventually get a resolution for that but it's been a real time drain. Can't believe how bad the documentation sucks. Give me 2 or 3 books with the software and the assistance of the forums and they can keep their ill-conceived and partly DEPRECATED (their term) documentation.

My best to you Stan. I'm not a happy camper today but I am mostly done with my conversion in just a month and a half, thanks in large measure to your forbearance.

--- Sam

[Stan Mathews]

Re: Playing &quot;tricks&quot; with strings

You'll see that the 17 year old Alpha V1 syntax works like a charm in the filter.

Because that's the syntax, without the quote() that I suggested. (Stopping the string and concatenating the variable.) You can also see that the same syntax works without the trailing +""

..........).AND."+ VCONMAG +""
same as
...........).AND."+ VCONMAG

The quote() isn't needed in your instance because it shouldn't be quoted in the filter. I was demonstrating a case in which the variable to be substituted needed to be quoted.

Try your expression again in the interactive an establish values beforehand for

VAR->VLDATE
VAR->VCNT1
VAR->VTOT1
VAR->VCNT2
VAR->VTOT2

and see if it works the same way as VCONMAG.

[sgerber]

Re: Playing &quot;tricks&quot; with strings

Thanks for responding, Stan. Thought you might have needed a break for a while.

I just tried what you asked in the Interactive window and of course you were right. I wasn't looking at the syntax correctly and didn't realize that the extra +"" at the end wasn't necessary. In fact, Stan, that may be the reason my expression isn't working in some of the form or report filters. I appreciate your calling that to my attention.

That query we've been discussing can't be done in a report or label filter so far as I can see because the "vconmag" variable is built on the fly after the xbasic script takes variables from the user. Also, that query is used to print mailing labels at a later point in time. My son, who owns the business that uses A5, will run the query multiple times with different parameters. He does this so he can select a certain number of customers for his mailing. When he reaches that number he will then print the mailing labels which is done by another script I'm writing.

That's why it's important for me to save his last query. The script that prints the labels will need to use it.

Do you have any thoughts, Stan, as to what a developer must do to save a query as a query list, not an index? Should I open a new thread for that topic instead.

As always, Stan, thank you. --- Sam

[Stan Mathews]

Re: Playing &quot;tricks&quot; with strings

Not necessary doesn't mean it should cause any issues. Just that sometimes it clouds the visualization of what is really happening.

I can think of no reason why you shouldn't be able to save a query.

Is the query based on a table or a set? When you are attempting to find/use the query is the layout based on the same table/set?

Try to design and save a query in AlphaSports on the customer table and locate it for the record selection of the CustomerLabels label layout.