Q141868: INFO: Visual FoxPro Language Tips and Tricks
Article: Q141868
Product(s): Microsoft FoxPro
Version(s):
Operating System(s):
Keyword(s): kbnokeyword kbHWMAC kbvfp300 kbvfp500 kbvfp600
Last Modified: 09-AUG-1999
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The information in this article applies to:
- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 6.0
- Microsoft Visual FoxPro for Macintosh, version 3.0b
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SUMMARY
=======
This article briefly describes some of the changes found in Visual FoxPro 3.0
and how to use the new features.
MORE INFORMATION
================
_SCREEN and activeControl Property
----------------------------------
In previous versions of FoxPro, you may have used the FoxPro system variable
_CUROBJ to refer to the object that currently had the focus. Although the
_CUROBJ variable has been retained for backward compatibility, Microsoft
recommends that you now refer to an object or control on a form by using the
_SCREEN reference and activeControl property. To return the name of the control
that has the focus use this code:
_SCREEN.activeform.activecontrol.name
-or-
thisform.activecontrol.name
-or- (if the form is part of a formset)
thisformset.thisform.activecontrol.name
To return the name of the current control, use this code:
CurControl=_SCREEN.activeform.activecontrol.name or
-or-
CurControl=thisform.activecontrol.name
-or- (if the form is part of a formset)
thisformset.CurControl=thisform.activecontrol.name
To set the caption of the current control, use this code:
_SCREEN.activeform.activecontrol.caption="my caption"
-or-
thisform.activecontrol.caption="my caption"
-or- (if the form is part of a formset)
thisformset.thisform.activecontrol.caption="my caption"
To move the cursor to a control, use this code:
_screen.activeform.<controlname>.setfocus
-or-
thisform.<controlname>.setfocus
-or- (if the form is part of a formset)
thisformset.thisform.<controlname>.setfocus
NOTE: <controlname> is the name of the control you wish to become active.
/N Parameter on the RUN Command
-------------------------------
The RUN command is available on the Windows platform only. The RUN command in
FoxPro for Windows has a /N parameter that allows you to launch a Windows-based
application. In fact, FoxPro for Windows introduced the /N option for executing
windows-based applications from FoxPro. This functionality is retained in Visual
FoxPro. The following command launches Word for Windows, and opens the readme
document.
RUN /N <drive><path>WINWORD.EXE README.DOC
The Microsoft Windows Control Panel contains many utilities that you can use in
your applications. You can also call these utilities using the RUN command:
RUN /N CONTROL COLOR
RUN /N CONTROL PRINTERS
RUN /N CONTROL DESKTOP
You can include an optional numeric value immediately after /N to specify how the
Windows-based application is opened. Do not include any spaces between /N and
the numeric value. The following table lists the numeric value you can include
and describes the state of the Windows-based application when opened.
Value Application attributes
------------------------------------------------
1 Active and normal size
2 Active and minimized
3 Active and maximized
4 Inactive and normal (won't work with Windows 95)
7 Inactive and minimized
Drives and Directories
----------------------
Several FoxPro functions can be used to obtain information about drives and
directories. Compare the returned values after issuing the command SET DEFAULT
TO C:\VFP.
Drive:
SYS(5) returns C:
SET('DEFAULT') returns C:
Directories:
CURDIR()returns \VFP\
SYS(2003) returns \VFP
FULL(SET('DEFA')) returns C:\VFP\
You can also use the ADIR() function to see if a specific directory exists. The
following example returns 0 only if the path name does not exist. Remember that
the path to a network server may not exist if the network connection is broken.
? ADIR(temparr,'C:\VFP\*.*','D')
returns 0
USE Command
-----------
You can run the USE IN 0 command to open a table or .dbf file in the first
available work area. This command does not select that work area in which it
opened the table or .dbf file. You must use the SELECT command to do this. You
can issue the command USE IN <alias> to close a table or .dbf file without
selecting its work area.
A new SHARED clause for the USE command allows you to open a table or .dbf file
for shared use without using the SET EXCLUSIVE command. For more information
about the USE command, refer to the USE topic in the Help file.
Cross-Tab Output to Spreadsheets
--------------------------------
Genxtab has been replaced by the Fpxtab program and is called from the code
created by the Query Wizard. After running the Query Wizard select the Cross-Tab
Wizard from the first screen, and follow the instructions to create a table that
can then be exported or copied to spreadsheets.
Custom Messages
---------------
You can display custom messages in the FoxPro status bar. To do this, type the
following in the Command window:
SET TALK OFF
SET MESSAGE TO <expC>
Where <expC> is the message. (You can pass a null string to display
nothing.) SET MESSAGE TO without a parameter will restore the status bar to its
normal functionality.
Preprocessor Directives
-----------------------
Do not use _WINDOWS, _DOS, _MAC, or _UNIX with preprocessor directives (that is,
#IF...#ENDIF). These are designed to be runtime variables. For example the
following will NOT work:
#define _DOS .t.
#define _WINDOWS .f.
* For code compiled in MS-DOS, the following would not work:
DO CASE
CASE _DOS
? "Running in MS-DOS"
CASE _WINDOWS
? "Running in Windows"
ENDCASE
This code would not work because _DOS would be changed to .T. and _WINDOWS would
be changed to .F. so that the code could never work properly again. Instead use
the following:
#if "Win" $ VERS()
#define WINDOWS_CODE .t.
#elif "Mac" $ VERS()
#define MAC_CODE .t.
#elif "Unix" $ VERS()
#define UNIX_CODE .t.
#else
#define DOS_CODE .t.
#ENDIF
#if WINDOWS_CODE
? "Compiled under WINDOWS"
#elif DOS_CODE
? "Compiled under MS-DOS"
#ENDIF
Preprocessor Substitution in Text Strings
-----------------------------------------
In FoxPro 2.6, #define prevented preprocessor substitution in text strings. This
has been remedied in Visual FoxPro. The following code will work as expected
returning the text 'test' from the function call. In FoxPro 2.x this would have
resulted in a 'NOSUB not found error' message. This is because of the way the
'[]' characters were evaluated.
#DEFINE nosub 1
DECLARE an_array(3)
an_array(nosub)='test'
? afunc[an_array[nosub]]
FUNCTION afunc
PARAMETER x
RETURN x
Development Tools
-----------------
The Foxtools.fll file, which is located in your FoxPro for Windows root
directory, contains a variety of functions you can use to enhance your
applications. Many of these functions provide access to API routines and
Microsoft Windows functions. You can view these by using the DISPLAY STATUS
command (after you use SET LIBRARY TO foxtools). Use of the window API routines
is also supported through the use of the DECLARE statement.
Additional query words:
======================================================================
Keywords : kbnokeyword kbHWMAC kbvfp300 kbvfp500 kbvfp600
Technology : kbHWMAC kbOSMAC kbVFPsearch kbAudDeveloper kbVFP300bMac kbVFP300 kbVFP300b kbVFP500 kbVFP600
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