The LA Fox Developer Newsletter

April 1998

Thought for the Month...

Playing Together Nicely

by David Rose, VFUG Editor

This is a testimonial to the many FoxPro developers out there on the bleeding edge. Sometimes that edge is using new technology, but increasingly that bleeding edge happens where old technology meets new technology. As software grows more componentized, there will be more problems getting the components to play together nicely. Within a development environment, this can be solved with careful configuration management. The real world isn’t always so accommodating.

When the problems occur from combinations of components, experience is the best source of knowledge. By exchanging problems and solutions, that experience is being leveraged by you, the network of developers looking for real world solutions to real world problems. Work with the network: ask questions, apply the answers, give yours to other developer’s questions and thereby enhance the richness of the community. Those best able to capitalize on this network will be the value-added experts that “can do” to make these systems work.

Wand’rin Aroun’

Brad Drury

Reprinted from OCFDG’s c-Newsletter

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Prevent Multiple Instances

of a Fox Application

by James E. Blatta

This is a routine to prevent multiple instances of a Fox application. The program was written for FoxPro 2.6 for Windows but should work in VFP with a bit of work.

The call is as follows:

MODIFY WINDOW screen TITLE ‘Starting Program’ COLOR

RGB(O,O,O,1 92,1 92,192) NOCLOSE CLEAR

IF CK4RUN(PROGRAM’,.t.)

QUIT

ENDIF

MODIFY WINDOW screen TITLE ‘Program’ COLOR; RGB(O,O,O,1 92,192,192)

NOCLOSE

CLEAR

A bit of this is spurious but the general idea is that the 2nd attempt to start the application must have a different name than the running application (so that it is unique). I add ‘starting’ so that it will always tell the user the program is starting. Once the check is made the main window is renamed to the actual program name (designated by ‘PROGRAM’).

I have it as the first lines. You need to use the two

modify window statements to get the thing to work. Also you can’t use other modify window screen statements in your application or the routine will fail and allow extra iterations of your applicaton. You could get around this by adding extra cases to CK4RUN but IMHO it is best to leave the main window title alone. See below for the complete CK4RUN program.

PROCEDURE CK4RUN

PARAMETERS _agver,_switch

InFindWln,InShowWin,InHnd

IF PARAMETER()=1

_switch.f.

ENDIF

IlRunning.F.

_foxtfnd=.f.

IF I’FOXTOOLS’$SET(’LIBRARY’)

_foxtfnd.t.

SET LIBRARY TO SYS(2004)+’FOXTOOLS.FLL’ ADDITIVE

ENDIF

InFindWin=RegFn(”FindWindow”,”CC”,”I”)

InShowWin=RegFn(”ShowWindow”,”II”.”I”)

InHnd __ CaIIFn(InFindWln,O,_agver)

DO CASE

CASE InHnd#O AND _switch.t.

CaIlFn(InShowWin,InHnd,O)

CaIIFn(InShowWin,InHnd,9)

llRunning = .T. CASE InHnd#O AND _switch.f.

llRunning = .T.

ENDCASE

(Con’t, page 8)

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