Forgotten () use

[jcfuller]

While dredging through some old code I ran across the below snippet that uses () around a STRING variable
to force the transformation to the required ASCIIZ.
I had a remembering flash that I once used this quite extensively in early PBDLL days but it somehow faded
into the dark recesses.
Recently if I needed this functionality I've used BYVAL STRPTR(S1)

Is this computer 101,PB 101 ....?

James

#COMPILE EXE
#DIM ALL
DECLARE FUNCTION MessageBox LIB "USER32.DLL" ALIAS "MessageBoxA" (BYVAL hWnd AS DWORD, lpText AS ASCIIZ, lpCaption AS ASCIIZ, BYVAL dwType AS DWORD) AS LONG
FUNCTION PBMAIN () AS LONG
    LOCAL S1      AS STRING
    LOCAL hDlg    AS LONG
    S1 = "James"
    MessageBox hDlg,(S1),"Title",IIF&(hDlg, 0, %MB_TOPMOST OR %MB_SETFOREGROUND)
END FUNCTION

[Patrice Terrier]

James,

I still use it quite often!

...

[Cliff Nichols]

I always thought it was some sort of typo. (Especially after server changes)

Never realized it was on purpose.

[Eddy Van Esch]

I did not even know that this feature existed ....
Is this mentioned somewhere in the help file?

Kind regards

[Michael Mattias]

In BASIC, using parens around a lone variable or an expression has always meant "the value of" ... kind of a shorthand "BYVAL" I guess.

I'm pretty sure I've seen something in help re using parens to force an evaluation, I can't find it now (not that I looked all that hard... it's not on the page pointed to by "(" in the index, which only talks about operator precedence).

[Edwin Knoppert]

If you self-declare..

DECLARE FUNCTION MessageBox LIB "USER32.DLL" ALIAS "MessageBoxA" (BYVAL hWnd AS DWORD, ByVal lpText AS String, ByVal lpCaption AS String, BYVAL dwType AS DWORD) AS LONG

[Paul Dixon]

From the help manual entry for CALL:

http://www.powerbasic.com/support/help/pbcc/call_statement.htm

Another way to force BYCOPY is to enclose a variable name in parentheses, so it will appear to the compiler as an expression, rather than just a single variable.

Paul.

[Michael Mattias]

I thought I'd seen use of parens documented "somewhere. "

Shouldn't that little piece of info also be found in the index entry for "(" too?

I'll send in a "documentation improvement suggestion. "

MCM

[Michael Mattias]

I sent this. I added the index entry idea for "()" based on this thread's title.

6/3/09

Gentlemen;

In PB/CC 5.0.1 and PB/Win 9.0.1 help for the CALL statement this explanation
appears in the sections with the "BYCOPY" caption:

" Another way to force BYCOPY is to enclose a variable name in parentheses,
so it will appear to the compiler as an expression, rather than just a
single variable. "

Yet, this same explanation does NOT appear in the help file entry linked to
the index entry for the left and right parens, which link only to the
'operator precedence' page.

I think you need to add a paragraph or something to show the use of parens
as "value forcing" in a page linked to the index entries for these symbols.

Or maybe better, add an index entry for the PAIR of parens "()" showing the
various uses of paired parens:
1. To establish explicit operator precedence (link to current page)
2. To enclose procedure parameters
3. To specify array subscripts
4. To force evaluation of a variable as an expression to take advantage of
the compiler's ability to make point-of-call data type conversions

You should also think about adding a comment about the use of parens as a
possibile cure for the 482 data type mismatch error in the "Errors" section
of the help file.

Michael C. Mattias
Tal Systems Inc.
Racine WI
[email protected]

[Patrice Terrier]

The BYCOPY () feature also exists in other languages

[Bob Zale]

Actually, PowerBASIC recommends you avoid the use of parentheses for this purpose. The functionality was added many years ago just for compatibility with that "ancient" compiler, qb for DOS. It has persisted only to avoid unnecessary problems moving from version to version with PowerBASIC. We removed documentation in order to foster adoption of other alternatives, specifically the BYCOPY override option. This provides the identical functionality, yet makes the purpose obvious when you visit the code later.

Best regards,

Bob Zale
PowerBASIC Inc.

[Michael Mattias]

Actually, PowerBASIC recommends you avoid the use of parentheses for this purpose

I don't suppose a futher documentation improvement suggestion to cancel my suggestion from yesterday and replace it with a suggestion to REMOVE the "helpful BYCOPY hint" in the doc for CALL is necessary.

Is it?