7.2 Example Trace Handler

This is an example of a self-contained Trace Handler object. It checks for the existence of a text file called TracingOn.txt and if found will install itself at run time and a trace file will be created. Any trace statements coded in to into the application will be output to this trace file.

Copy and paste the source in to into a new RDMLX reusable part. Save and compile.

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     Function Options(*DIRECT)

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     Begin_

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Com Role(*

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EXTENDS #PRIM_OBJT *implements #prim_app.iTraceHandler)

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     Define Field(#FilHandle)

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 Type(*dec)

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 Length(3)

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 Decimals(0)

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     Define_

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Com Class(#prim_alph)

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 Name(#Tab)

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     Evtroutine Handling(#Com_Owner.CreateInstance)

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     #Tab :=

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 (09).asChar 
     

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#Com_owner.InstallTracing 
     

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Endroutine 
     Mthroutine Name(InstallTracing)

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 Help('

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Plug in the trace handler to the Application')

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 Access(*private)

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     * This example uses a text file as the trigger to implement user tracing. 
     * Alternately you might consider using a registry entry

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     If (#Com_owner.FileExists( (*Sys_dir  "TracingOn.txt") )) 
     

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* Set this object as the system help handler 
     

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#Sys_appln.TraceHandler <= #Com_owner 
     

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Endif 
     

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Endroutine 
     

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Mthroutine Name(Initialize) Options(*redefine) Access(*private) 
     

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#Com_owner.OpenTraceFile 
     

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Endroutine 
     

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Mthroutine Name(Terminate) Options(*redefine) Access(*private) 

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     #Com_owner.CloseTraceFile

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     Endroutine 
     Mthroutine Name(TraceMessage) Help('Executed whenever #sys_appln.TraceMessageData or #sys_appln.TraceMessageText is used') Options(*redefine) Access(*private)
     

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#Com_owner.WriteToFile( #ComponentName #Description #LineNumber #MessageText ) 
     Endroutine 
     Mthroutine Name(OpenTraceFile) Help('Create a new trace outputfile') Access(*private) 
     

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Use Builtin(Stm_File_Open) With_Args(#Com_owner.GetNextFile Append N Y) To_Get(#FilHandle #io$sts) 
     

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Endroutine 
     

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Mthroutine Name(WriteToFile) Help('Write an entry in the trace output file') Access(*private)

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     Define_Map For(*Input) Class(#prim_alph) Name(#ComponentName) 
     

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Define_Map For(*Input) Class(#prim_alph) Name(#Description) 
     

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Define_Map For(*Input) Class(#prim_nmbr) Name(#LineNumber) 
     

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Define_Map For(*Input) Class(#prim_alph) Name(#MessageText) 
     

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Define_Com Class(#prim_Dat) Name(#Now) 
     

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#MessageText := Now.now.AsLocalizedDateTime.AsString  #Tab  #ComponentName  #Tab  #LineNumber.asstring  #Tab  #MessageText 
     

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Use Builtin(Stm_File_Write) With_Args(#FilHandle #MessageText) To_Get(#io$sts) 
     

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Endroutine 
     

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Mthroutine Name(CloseTraceFile) Access(*private) 
     

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Use Builtin(Stm_File_Close) With_Args(#FilHandle) To_Get(#io$sts) 

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     Endroutine 

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     Mthroutine Name(TracingState) Options(*redefine) 

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#MessageTracingActive := True 

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     Endroutine 
     Mthroutine Name(GetNextFile) Access(*Private)

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     Define_Map For(*Result) Class(#Prim_alph) Name(#Result) 
     

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Define_Com Class(#prim_nmbr) Name(#Extension) 
     

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Begin_Loop Using(#Extension) 
     

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#Result := *Sys_dir  "UserTrace"  "."  #Extension.asstring.rightAdjust( 3 "0" ) 
     

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Leave If(*Not #Com_owner.FileExists( #Result )) 

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     End_Loop 
     

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Endroutine 
     

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Mthroutine Name(FileExists) Access(*private) 
     

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Define_Map For(*input) Class(#prim_alph) Name(#Path) 
     

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Define_Map For(*result) Class(#prim_boln) Name(#Result) 
     

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Use Builtin(OV_FILE_SERVICE) With_Args(Check_File #Path) To_Get(#io$sts) 
     

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#Result := (#io$sts = OK) 
     

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Endroutine 
     End_Com