SYS(2335) - Unattended Server Mode
Enables or disables modal states for distributable Visual FoxPro .exe automation servers.
SYS(2335 [, 0 | 1])
Return Value
Character
Parameters
0
Enables unattended mode. When unattended mode is enabled, a Visual FoxPro error is generated whenever a modal state occurs. Your .exe automation server can trap for these errors with an ON ERROR routine.1
(Default) Disables unattended mode. Modal states, which require user intervention, can occur. Unattended mode is disabled at startup.
Remarks
Use SYS(2335) to enable or disable modal states in Visual FoxPro .exe automation servers. Automation servers are created with the Project Manager. For additional information about using Visual FoxPro to create .exe automation servers, see Sharing Information and Adding OLE.
Modal states occur when dialogs or errors messages are displayed, requiring input from a user to exit the dialog or error message and continue program execution. Modal states can be undesirable in .exe servers that are deployed remotely, possibly without intervention from a user. Program execution is halted, and requires intervention for program execution to continue.
The following table lists some typical examples of modal states that can occur in an .exe server.
Modal State |
Examples |
|---|---|
WAIT command or MESSAGEBOX( ) function |
Can occur in program code. |
Visual FoxPro errors such as "File access is denied" or "Allowed DO nesting level exceeded" |
Can occur in program code. |
Open dialog boxes |
Can occur when files included in a SQL statement cannot be located. |
SQL Connection Login dialog box |
Can occur after a connection cannot be established. |
SYS(2335 ,0) should be executed as soon as possible in unattended .exe automation server program code because a modal state can occur anytime after program execution begins.
Note that SYS(2335) applies only to .exe automation servers for which the StartMode property equals 2 or 4. Unattended mode is always enabled for in-process .dll automation servers (for which the StartMode property equals 3).
Issuing SYS(2335) without an argument in a runtime application returns its current setting.
Example
The following example allows you to run several test cases to show the results of SYS(2335) settings in an application that invokes modal user interface elements.
CLEAR
SET SAFETY OFF
DIMENSION aTestCase[3]
aTestCase[1]="TestMessageBox"
aTestCase[2]="LocateFileDialog"
aTestCase[3]="SafetyDialog"
TEXT TO cstr TEXTMERGE
PROCEDURE Temp(UIMode as string,cTestCase as string)
* command line parms are strings
SYS(2335,VAL(UIMode)) && allow or disallow UI
SET SAFETY OFF
TRY
_screen.Caption="UIMode = "+UIMode+" "+cTestCase+" Startmode="+TRANSFORM(_vfp.StartMode)
DO CASE
CASE cTestCase="<<aTestCase[1]>>"
MESSAGEBOX("UI is allowed. UIMode = "+UIMode,0, cTestCase)
CASE cTestCase="<<aTestCase[2]>>"
*Try this scenario which will bring up a dialog
SELECT * FROM NonExistFile
CASE cTestCase="<<aTestCase[3]>>"
*Cause "Overwrite existing file dialog to appear"
SET SAFETY ON
CREATE TABLE temp (name c(10),data m)
CREATE TABLE temp (name c(10),data m) && Create table again to cause Overwrite dialog?
OTHERWISE
MESSAGEBOX("Unknown test case. UIMode = "+UIMode+" "+cTestCase)
ENDCASE
CATCH TO oEx
SYS(2335,1) && Allow UI
MESSAGEBOX("Err caught UIMode = "+UIMode+":"+oEx.Message + " " +oEx.details,48,"Exception "+cTestCase)
ENDTRY
ENDTEXT
STRTOFILE(cstr,"temp.prg")
BUILD PROJECT temp FROM temp
BUILD EXE temp FROM temp
FOR nTestCase=1 TO ALEN(aTestCase)
FOR uiMode=1 TO 0 STEP -1
?"UIMode=",uiMode,aTestCase[nTestCase]
cCmd="temp "+TRANSFORM(uiMode)+" "+aTestCase[nTestCase]
! &cCmd
ENDFOR
EXIT && comment this to run the other test cases
ENDFOR