The Trace library provides functions for tracing program execution and debugging code. It allows setting trace points to log events, control flow between functions, handle errors, and open an interactive debugger. The debugger allows stepping through code line-by-line, viewing variable values, and executing Ring code to debug programs. Breakpoints can be used to pause execution and enter the debugger.

1. Ring Documentation, Release 1.6
ok
ok
see nl + Copy("=",42) + nl
class myclass
func mymethod
see "Message from mymethod" + nl
Output:
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : After C Function
Line Number : 3
File Name : test1.ring
Function Name : ringvm_settrace
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 5
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
Hello, world!
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 6
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
Welcome
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 7
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
How are you?
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 8
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Function
Line Number : 8
File Name : test1.ring
68.24. Example - Using the Trace Functions 783

2. Ring Documentation, Release 1.6
Function Name : mytest
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 12
File Name : test1.ring
Function Name : mytest
Method or Function : Function
==========================================
Message from mytest
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 14
File Name : test1.ring
Function Name : mytest
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : Return
Line Number : 8
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 9
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 43
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : Before C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : After C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
68.24. Example - Using the Trace Functions 784

3. Ring Documentation, Release 1.6
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Function
Line Number : 9
File Name : test1.ring
Function Name : mymethod
Method or Function : Method
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 44
File Name : test1.ring
Function Name : mymethod
Method or Function : Method
==========================================
Message from mymethod
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : Return
Line Number : 9
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : Before C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : After C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : Before C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : After C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
Method or Function : Function
68.24. Example - Using the Trace Functions 785

4. Ring Documentation, Release 1.6
==========================================
====== The Trace function is Active ======
Trace Function Name : mytrace()
Trace Event : New Line
Line Number : 11
File Name : test1.ring
Function Name :
Method or Function : Command
==========================================
68.25 Example - The Trace Library
The next example uses the Trace functions provided by the Ring language to create the Trace library.
Using the Trace library we have nice Tracing tools and Interaction debugger too.
# Trace Events
TRACEEVENT_NEWLINE = 1
TRACEEVENT_NEWFUNC = 2
TRACEEVENT_RETURN = 3
TRACEEVENT_ERROR = 4
TRACEEVENT_BEFORECFUNC = 5
TRACEEVENT_AFTERCFUNC = 6
# Trace Data
TRACEDATA_LINENUMBER = 1
TRACEDATA_FILENAME = 2
TRACEDATA_FUNCNAME = 3
TRACEDATA_METHODORFUNC = 4
# Method of Function
TRACEDATA_METHODORFUNC_METHOD = TRUE
TRACEDATA_METHODORFUNC_NOTMETHOD = FALSE
TRACE_BREAKPOINTS = TRUE
TRACE_TEMPLIST = []
func Trace cType
switch trim(lower(cType))
on :AllEvents
ringvm_settrace("TraceLib_AllEvents()")
on :Functions
ringvm_settrace("TraceLib_Functions()")
on :PassError
ringvm_settrace("TraceLib_PassError()")
on :Debugger
ringvm_settrace("TraceLib_Debugger()")
on :LineByLine
ringvm_settrace("TraceLib_LineByLine()")
off
func TraceLib_AllEvents
if right(ringvm_tracedata()[TRACEDATA_FILENAME],13) = "tracelib.ring"
return
ok
see "====== The Trace function is Active ======" + nl +
68.25. Example - The Trace Library 786

5. Ring Documentation, Release 1.6
"Trace Function Name : " + ringvm_TraceFunc() + nl +
"Trace Event : "
switch ringvm_TraceEvent()
on TRACEEVENT_NEWLINE see "New Line"
on TRACEEVENT_NEWFUNC see "New Function"
on TRACEEVENT_RETURN see "Return"
on TRACEEVENT_ERROR see "Error"
on TRACEEVENT_BEFORECFUNC see "Before C Function"
on TRACEEVENT_AFTERCFUNC see "After C Function"
off
see nl +
"Line Number : " + ringvm_tracedata()[TRACEDATA_LINENUMBER] + nl +
"File Name : " + ringvm_tracedata()[TRACEDATA_FILENAME] + nl +
"Function Name : " + ringvm_tracedata()[TRACEDATA_FUNCNAME] + nl +
"Method or Function : "
if ringvm_tracedata()[TRACEDATA_METHODORFUNC] =
TRACEDATA_METHODORFUNC_METHOD
see "Method"
else
if ringvm_tracedata()[TRACEDATA_FUNCNAME] = NULL
see "Command"
else
see "Function"
ok
ok
see nl + Copy("=",42) + nl
func TraceLib_Functions
if right(ringvm_tracedata()[TRACEDATA_FILENAME],13) = "tracelib.ring"
return
ok
switch ringvm_TraceEvent()
on TRACEEVENT_NEWFUNC
see "Open Func : " +
ringvm_TraceData()[TRACEDATA_FUNCNAME] + nl
on TRACEEVENT_RETURN
see "Return to Func : " +
ringvm_TraceData()[TRACEDATA_FUNCNAME] + nl
off
func TraceLib_PassError
if right(ringvm_tracedata()[TRACEDATA_FILENAME],13) = "tracelib.ring"
return
ok
switch ringvm_TraceEvent()
on TRACEEVENT_ERROR
see nl
see "TraceLib : After Error !" + nl
ringvm_passerror()
off
func TraceLib_Debugger
if right(ringvm_tracedata()[TRACEDATA_FILENAME],13) = "tracelib.ring"
return
ok
switch ringvm_TraceEvent()
on TRACEEVENT_ERROR
_BreakPoint()
68.25. Example - The Trace Library 787

6. Ring Documentation, Release 1.6
off
func TraceLib_LineByLine
if right(ringvm_tracedata()[TRACEDATA_FILENAME],13) = "tracelib.ring" or
ringvm_TraceEvent() != TRACEEVENT_NEWLINE
return
ok
aList = ringvm_tracedata()
see "Before Line : " + aList[TRACEDATA_LINENUMBER] + nl
_BreakPoint()
func BreakPoint
if not TRACE_BREAKPOINTS
return
ok
_BreakPoint()
func _BreakPoint
see nl+nl+Copy("=",60) + nl +
Copy(" ",20)+"Interactive Debugger" + nl +
Copy("=",60) + nl +
"Command (Exit) : End Program" + nl +
"Command (Cont) : Continue Execution" + nl +
"Command (Locals) : Print local variables names" + nl +
"Command (LocalsData) : Print local variables data" + nl +
"Command (Globals) : Print global variables names" + nl +
"We can execute Ring code" + nl +
Copy("=",60) + nl
while true
see nl + "code:> "
give cCode
cmd = trim(lower(cCode))
if cmd = "exit" or cmd = "bye"
shutdown()
ok
nScope = ringvm_scopescount()-2
switch cmd
on "locals"
ringvm_EvalInScope(nScope,"see locals() callgc()")
loop
on "localsdata"
PrintLocalsData(nScope)
loop
on "globals"
ringvm_EvalInScope(nScope,"see globals() callgc()")
loop
on "cont"
ringvm_passerror()
exit
off
Try
ringvm_EvalInScope(nScope,cCode)
catch
see cCatchError
done
end
func NoBreakPoints
68.25. Example - The Trace Library 788

7. Ring Documentation, Release 1.6
TRACE_BREAKPOINTS = FALSE
func PrintLocalsData nScope
if nScope = 1 # Global
ringvm_Evalinscope(nScope,'TRACE_TEMPLIST = globals()')
else
ringvm_Evalinscope(nScope,'TRACE_TEMPLIST = locals() callgc()')
ok
see nl
aTempList = TRACE_TEMPLIST
TRACE_TEMPLIST = []
nSpaces = 5
for TRACE_ITEM in aTempList
if len(TRACE_ITEM) + 5 > nSpaces
nSpaces = len(TRACE_ITEM) + 5
ok
next
for TRACE_ITEM in aTempList
see "Variable : " + TRACE_ITEM
cVarName = TRACE_ITEM
see copy(" ",nSpaces-len(cVarName)) + " Type : "
ringvm_Evalinscope(nScope,"see type(" + TRACE_ITEM +")")
ringvm_Evalinscope(nScope,"see Copy(' ',fabs(15-len(type(" +
TRACE_ITEM +"))))")
see " Value : "
ringvm_Evalinscope(nScope,"see " + TRACE_ITEM)
see nl
next
68.25. Example - The Trace Library 789

8. CHAPTER
SIXTYNINE
THE TRACE LIBRARY AND THE INTERACTIVE DEBUGGER
In this chapter we will learn about the Trace Library and the Interactive Debugger
69.1 Loading the Trace library
To start using the Trace library, We must load it first!
load "tracelib.ring"
69.2 Trace All Events
The next example demonstrates the Trace library usage to trace all events.
# Trace All Events
trace(:AllEvents)
see "Hello, world!" + nl
see "Welcome" + nl
see "How are you?" +nl
mytest()
new myclass { mymethod() }
func mytest
see "Message from mytest" + nl
class myclass
func mymethod
see "Message from mymethod" + nl
69.3 Trace control flow between functions
The next example demonstrates the Trace library usage to trace the control flow between functions.
Trace(:Functions)
test1()
790

9. Ring Documentation, Release 1.6
func test1
see :test1 + nl
test2()
func test2
see :test2 + nl
see test3() + nl
func test3
see :test3 + nl
return "test 3 output"
69.4 Pass Error
The next example demonstrates the Trace library usage to pass an error!
Trace(:PassError)
test1()
func test1
x = 10
see :test1 + nl
test2() # Runtime Error!
see "We can continue!"
69.5 Interactive Debugger
The next example demonstrates the Trace library usage to use the Interactive Debugger
Trace(:Debugger)
test1()
see "good bye!" + nl
func test1
x = 10
see :test1 + nl
t = 12
test2() # Runtime Error!
see "After Error!" +nl
see "t = " see t see nl
see "x = " see x see nl
69.6 Execute Program Line by Line
The next example demonstrates the Trace library usage to execute the program line by line!
Trace(:LineByLine)
test1()
69.4. Pass Error 791

10. Ring Documentation, Release 1.6
func test1
x = 10
see :test1 + nl
t = 12
test2()
see "After Error!" +nl
see "t = " + t + nl
69.7 BreakPoint
The next example demonstrates the Trace library usage to stop at a breakpoint!
test1()
func test1
x = 10
see :test1 + nl
t = 12
BreakPoint()
see "After breakpoint!" +nl
see "t = " + t + nl
see "End of program!" + nl
69.8 Disable BreakPoints
The next example demonstrates the Trace library usage and how to disable the Breakpoints!
NoBreakPoints()
test1()
func test1
x = 10
see :test1 + nl
t = 12
BreakPoint()
see "After breakpoint!" +nl
see "t = " + t + nl
see "End of program!" + nl
69.9 Using the Interactive Debugger
The next example uses a Breakpoint to open the Interactive Debugger!
load "tracelib.ring"
test1()
func test1
x = 10
see :test1 + nl
t = 12
69.7. BreakPoint 792