xbasic for everyone Dr Wayne

[Peter.Wayne]

Re: xbasic for everyone Dr Wayne

Marcel,
That's a problem with the help files, not with the book!
- Peter

[Marcel Kollenaar]

Re: xbasic for everyone Dr Wayne

Marcel,
That's a problem with the help files, not with the book!
- Peter

;) Peter, you are a good salesman.

[dik_coleman]

Re: xbasic for everyone Dr Wayne

Ran into an interesting situation on page 147....
The script (to be put on a button) to change font color...

Using 'option strict' as written and exactly typing the script kept getting an error.
The error was on 'line 10' (may be different in yours)
the line is : for i=1 to count
the error is : variable not found....

after a bit of sleuthing, I found out that you either have to eliminate the 'option strict' OR dim the variable i -- dim i as n

With that all works fine...

Just info
D

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

Dr. Wayne,

I spotted a typo on page 69. it's simply a typographical error. In the last main paragraph there is a sentence that reads:

If you use queries, you never have to worry about what indexes are present; and if you find that a frequently used script runs slowly and believe that an index will speed it up, then the proper approach is to add the index and left Alpha Five use it to optimize the query.

Looks like you meant let...

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

on pgs. 76-77 the emty_all() function at the bottom of the page doesn't close the tables it opens anywhere. Isn't this a bad thing?

it reads:

on error goto failure
for i=1 to 5
      tbl=table.open(table_names[i],file_rw_exclusive)
      tbl.zap(.t.)
next i
 
[COLOR=blue][U]with the error handler reading:[/U][/COLOR]
 
failure:
empty_all=.f.
on error goto 0
exit function

looks like it should read:

on error goto failure
for i=1 to 5
      tbl=table.open(table_names[i],file_rw_exclusive)
      tbl.zap(.t.)
      [COLOR=red]if is_object(tbl) then 
           tbl.close()[/COLOR]
next i
 
[COLOR=blue][U]with the error handler reading:[/U][/COLOR]
 
failure:
empty_all=.f.
[COLOR=red]if is_object(tbl) then 
    tbl.close()[/COLOR]
end if 
on error goto 0
exit function

Am I off base here?

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

pg. 78 the nextMeeting() fuction has an error:

The use of the nth_dow() Alpha 5 function is incorrect. It reads:

' get second wednesday of month
trial_date=nth_dow("friday",m,y,2) 'built-in Alpha Five function

did you spot the error?

it should have read:

' get second [COLOR=red]wednesday[/COLOR] of month
trial_date=nth_dow("[COLOR=red]wednesday[/COLOR]",m,y,2) 'built-in Alpha Five function

[Finian Lennon]

Re: xbasic for everyone Dr Wayne

The code in the " on error goto " trap is designed to fire if (1) there was an error on the "for i = " line and/or (2) if the table.open fails to get exclusive access to the table.

Putting a close after the error would simply cause another error since in neither case was the table opened.

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

pg. 81 in the aged accounts receivable example when the query filter is set as:

query.filter="Invoice_Balance>0.01"

shouldn't it be:

query.filter="Invoice_Balance[COLOR=red]>=[/COLOR]0.01"

....nevermind. :) I hadn't read the next page when I posted this one. my bad.

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

The code in the " on error goto " trap is designed to fire if (1) there was an error on the "for i = " line and/or (2) if the table.open fails to get exclusive access to the table.

Putting a close after the error would simply cause another error since in neither case was the table opened.

the "on error goto" trap should go off if "ANY" error occurs. this would include the case where the tbl.zap(.t.) fails wouldn't it? If yes, then when the zap() fails the table would be left open.

In addition, the close() statement is not used at all in the function. Five tables get opened but never closed...?

Furthermore, I use:

if is_object(tbl) then 
           tbl.close()

to test the tbl pointer to see if it still references a valid object. I close() the table if and only if the table pointer is still pointing to an object.

[Finian Lennon]

Re: xbasic for everyone Dr Wayne

It all depends on your approach.

In the code you cite, the "on error goto" is anticipating a reasonably expected error over which the coder has no control, namely the table.open requiring exclusive access. Once the table is open, you wouldn't reasonably expect the .zap to cause an error. If you do, then you might as well set a trap for every Alpha action in every script.

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

It all depends on your approach.

In the code you cite, the "on error goto" is anticipating a reasonably expected error over which the coder has no control, namely the table.open requiring exclusive access. Once the table is open, you wouldn't reasonably expect the .zap to cause an error. If you do, then you might as well set a trap for every Alpha action in every script.

although a zap isn't likely to fail it can happen. Wouldn't it be a "best practice" to make sure the table gets closed?

My main point in my post was really that the tables were being explicitly opened by the script but never closed. Am I wrong on this point? Are the tables being closed as the script ends and the table_names[5] variable goes out of scope?

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

Another peculiarity... I've noticed that many of the scripts in this book will declare a bunch of variables, some of which have their DIM and type portion of their declarations capitalized while others don't. The reasoning isn't very apparent to me. XBasic is case-insensitive right?

Example: pg.127

dim Balance as [COLOR=red]N[/COLOR]
dim t as p
dim search as c
     .
     .
     .

Example: pg.91

[COLOR=red]'[/COLOR]DIM SHARED lastname as C  [COLOR=red]<-- is that ' a typo? or was it intended?[/COLOR]
DIM SHARED firstname as C
DIM SHARED varC_result as C
[COLOR=red]dim[/COLOR] ok_enabled as [COLOR=red]l[/COLOR]

Dr. Wayne? :)

[Peter.Wayne]

Re: xbasic for everyone Dr Wayne

Thanks to everyone for pointing out errors and inconsistencies. Some of these are simple, like the change from "wednesday" to "friday", or "left" instead of "let", but I appreciate close readers! It makes me feel someone is actually studying the scripts!
And yes, I goofed up on a couple of scripts which I wrote and debugged but then added "option strict" to and forgot to DIM a variable.
Re closing tables: Xbasic scripts automatically close tables when the script closes, unless tbl.persist() is used. Nevertheless, I agree it's always good practice to explicitly close tables.
As for the capitalizations, I'm not very consistent in my scripts. I tend to use lower case but the code editor, when you ask it to DIM unDIMmed variables, uses upper case, so many of my scripts use a mix of cases for variable types and names. Very sloppy and unprofessional but that's what you get when you buy a book written by a nonprofessional programmer!

[Jeff@Listbrokers]

Re: xbasic for everyone Dr Wayne

Thanks for clearing things up. I can definitely live with a few typos, your book is a very informative, easy read. Glad you wrote it. :)

[dik_coleman]

Re: xbasic for everyone Dr Wayne

to Jeff --

I think that alot of the capitalization of things like 'DIM' is caused when programmers use the Action Scripting Genie while in XBasic mode....

I have noticed that only some of the words that make up an XDialog box are capitalized and most (maybe all) are words that the genie has to put into the code based on the choices made by the programmer...

Anyone else have ideas??

D