TCL_STDERR channel not working
in [TCL]
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From: sandy on 2 Jul 2008 23:56 Hello, I'm trying to embed tcl interepreter in my c code and wanted to redirect stdout and stderr to different files. stdout works fine but stderr (errlog.txt) is always empty( even though tcl script contain errors). I am trying this first time, please suggest. ---- Here is the code --- main (int argc, char *argv[]) { Tcl_Interp *interp; int code, temp; interp = Tcl_CreateInterp(); Tcl_Channel stdconsoleChannel; stdconsoleChannel = Tcl_OpenFileChannel(interp, "outlog.txt", "w+", 777); Tcl_SetStdChannel(stdconsoleChannel, TCL_STDOUT); Tcl_Channel errconsoleChannel; errconsoleChannel = Tcl_OpenFileChannel(interp, "errlog.txt", "w+", 777); Tcl_SetStdChannel(errconsoleChannel, TCL_STDERR); code = Tcl_EvalFile(interp, argv[1]); Tcl_DeleteInterp(interp); exit(0); }
From: Alexandre Ferrieux on 3 Jul 2008 04:24 On Jul 3, 5:56 am, sandy <motif_u...(a)yahoo.com> wrote: > Hello, > > I'm trying to embed tcl interepreter in my c code and wanted to > redirect stdout and stderr to > different files. stdout works fine but stderr (errlog.txt) is always > empty( even though tcl script > contain errors). I am trying this first time, please suggest. > > ---- Here is the code --- > > main (int argc, char *argv[]) > { > Tcl_Interp *interp; > int code, temp; > > interp = Tcl_CreateInterp(); > > Tcl_Channel stdconsoleChannel; > stdconsoleChannel = Tcl_OpenFileChannel(interp, "outlog.txt", > "w+", 777); > Tcl_SetStdChannel(stdconsoleChannel, TCL_STDOUT); > > Tcl_Channel errconsoleChannel; > errconsoleChannel = Tcl_OpenFileChannel(interp, "errlog.txt", > "w+", 777); > Tcl_SetStdChannel(errconsoleChannel, TCL_STDERR); > > code = Tcl_EvalFile(interp, argv[1]); > > Tcl_DeleteInterp(interp); > > exit(0); > > } The fact that the script has errors doesn't imply immediate output to stderr. Instead, Tcl_EvalFile will return TCL_ERROR, the interp's result containing the error message, and it is up to the caller to provide an outer "last chance handler". So, my bet is that Tcl_SetStdChannel(TCL_STDERR) works fine, and you can verify this prediction by adding into your script: puts stderr Hey! flush stderr before any error. Once this is verified, either write the outer handler at the C level as suggested above, or in Tcl by wrapping your script in a [catch]. By the way, tclsh and wish both provide excellent outer handlers. Are you sure you really want to embed, instead of extending Tcl ? Please describe your situation. -Alex
From: sandy on 4 Jul 2008 05:47 On Jul 3, 1:24 pm, Alexandre Ferrieux <alexandre.ferri...(a)gmail.com> wrote: > On Jul 3, 5:56 am, sandy <motif_u...(a)yahoo.com> wrote: > > > > > > > Hello, > > > I'm trying to embed tcl interepreter in my c code and wanted to > > redirect stdout and stderr to > > different files. stdout works fine but stderr (errlog.txt) is always > > empty( even though tcl script > > contain errors). I am trying this first time, please suggest. > > > ---- Here is the code --- > > > main (int argc, char *argv[]) > > { > > Tcl_Interp *interp; > > int code, temp; > > > interp = Tcl_CreateInterp(); > > > Tcl_Channel stdconsoleChannel; > > stdconsoleChannel = Tcl_OpenFileChannel(interp, "outlog.txt", > > "w+", 777); > > Tcl_SetStdChannel(stdconsoleChannel, TCL_STDOUT); > > > Tcl_Channel errconsoleChannel; > > errconsoleChannel = Tcl_OpenFileChannel(interp, "errlog.txt", > > "w+", 777); > > Tcl_SetStdChannel(errconsoleChannel, TCL_STDERR); > > > code = Tcl_EvalFile(interp, argv[1]); > > > Tcl_DeleteInterp(interp); > > > exit(0); > > > } > > The fact that the script has errors doesn't imply immediate output to > stderr. Instead, Tcl_EvalFile will return TCL_ERROR, the interp's > result containing the error message, and it is up to the caller to > provide an outer "last chance handler". > > So, my bet is that Tcl_SetStdChannel(TCL_STDERR) works fine, and you > can verify this prediction by adding into your script: > > puts stderr Hey! > flush stderr > > before any error. > Once this is verified, either write the outer handler at the C level > as suggested above, or in Tcl by wrapping your script in a [catch]. > > By the way, tclsh and wish both provide excellent outer handlers. > Are you sure you really want to embed, instead of extending Tcl ? > Please describe your situation. > > -Alex- Hide quoted text - > > - Show quoted text - Thanks Alex, Just, one more question. In my application I want to send device commands through serial port. Suppose I am sending device commands through tcl loop, how can i make tcl loop executes only as fast as my serial device can handle it? What I have observed is that tcl loop finished much faster then the device and data gets lost. Thanks, sandy
From: Alexandre Ferrieux on 4 Jul 2008 06:00 On Jul 4, 11:47 am, sandy <motif_u...(a)yahoo.com> wrote: > On Jul 3, 1:24 pm, Alexandre Ferrieux <alexandre.ferri...(a)gmail.com> > wrote: > > > > > On Jul 3, 5:56 am, sandy <motif_u...(a)yahoo.com> wrote: > > > > Hello, > > > > I'm trying to embed tcl interepreter in my c code and wanted to > > > redirect stdout and stderr to > > > different files. stdout works fine but stderr (errlog.txt) is always > > > empty( even though tcl script > > > contain errors). I am trying this first time, please suggest. > > > > ---- Here is the code --- > > > > main (int argc, char *argv[]) > > > { > > > Tcl_Interp *interp; > > > int code, temp; > > > > interp = Tcl_CreateInterp(); > > > > Tcl_Channel stdconsoleChannel; > > > stdconsoleChannel = Tcl_OpenFileChannel(interp, "outlog.txt", > > > "w+", 777); > > > Tcl_SetStdChannel(stdconsoleChannel, TCL_STDOUT); > > > > Tcl_Channel errconsoleChannel; > > > errconsoleChannel = Tcl_OpenFileChannel(interp, "errlog.txt", > > > "w+", 777); > > > Tcl_SetStdChannel(errconsoleChannel, TCL_STDERR); > > > > code = Tcl_EvalFile(interp, argv[1]); > > > > Tcl_DeleteInterp(interp); > > > > exit(0); > > > > } > > > The fact that the script has errors doesn't imply immediate output to > > stderr. Instead, Tcl_EvalFile will return TCL_ERROR, the interp's > > result containing the error message, and it is up to the caller to > > provide an outer "last chance handler". > > > So, my bet is that Tcl_SetStdChannel(TCL_STDERR) works fine, and you > > can verify this prediction by adding into your script: > > > puts stderr Hey! > > flush stderr > > > before any error. > > Once this is verified, either write the outer handler at the C level > > as suggested above, or in Tcl by wrapping your script in a [catch]. > > > By the way, tclsh and wish both provide excellent outer handlers. > > Are you sure you really want to embed, instead of extending Tcl ? > > Please describe your situation. > > > -Alex- Hide quoted text - > > > - Show quoted text - > > Thanks Alex, > > Just, one more question. > > In my application I want to send device commands through serial port. > > Suppose I am sending device commands through tcl loop, how can i make > tcl loop executes only as fast as my serial device can handle it? What > I have observed is that tcl loop finished much faster then the device > and data gets lost. The problem is not with the event loop, it has to do with low-level flow control being enabled or not. When you [puts] to a channel in Tcl, sonner or later a write() syscall will occur. For a socket, pipe, or file, you have a stream semantics, in that no data is lost: the write is done either in blocking or nonblocking mode, but in the latter case data not immediately writte are retried later. For a serial port, if flow control is enabled, it should work the same. But maybe this requires the physical device on the other side to cooperate... Now you didn't answer *my* question ;-) -Alex
From: sandy on 4 Jul 2008 08:16
On Jul 4, 3:00 pm, Alexandre Ferrieux <alexandre.ferri...(a)gmail.com> wrote: > On Jul 4, 11:47 am, sandy <motif_u...(a)yahoo.com> wrote: > > > > > > > On Jul 3, 1:24 pm, Alexandre Ferrieux <alexandre.ferri...(a)gmail.com> > > wrote: > > > > On Jul 3, 5:56 am, sandy <motif_u...(a)yahoo.com> wrote: > > > > > Hello, > > > > > I'm trying to embed tcl interepreter in my c code and wanted to > > > > redirect stdout and stderr to > > > > different files. stdout works fine but stderr (errlog.txt) is always > > > > empty( even though tcl script > > > > contain errors). I am trying this first time, please suggest. > > > > > ---- Here is the code --- > > > > > main (int argc, char *argv[]) > > > > { > > > > Tcl_Interp *interp; > > > > int code, temp; > > > > > interp = Tcl_CreateInterp(); > > > > > Tcl_Channel stdconsoleChannel; > > > > stdconsoleChannel = Tcl_OpenFileChannel(interp, "outlog.txt", > > > > "w+", 777); > > > > Tcl_SetStdChannel(stdconsoleChannel, TCL_STDOUT); > > > > > Tcl_Channel errconsoleChannel; > > > > errconsoleChannel = Tcl_OpenFileChannel(interp, "errlog.txt", > > > > "w+", 777); > > > > Tcl_SetStdChannel(errconsoleChannel, TCL_STDERR); > > > > > code = Tcl_EvalFile(interp, argv[1]); > > > > > Tcl_DeleteInterp(interp); > > > > > exit(0); > > > > > } > > > > The fact that the script has errors doesn't imply immediate output to > > > stderr. Instead, Tcl_EvalFile will return TCL_ERROR, the interp's > > > result containing the error message, and it is up to the caller to > > > provide an outer "last chance handler". > > > > So, my bet is that Tcl_SetStdChannel(TCL_STDERR) works fine, and you > > > can verify this prediction by adding into your script: > > > > puts stderr Hey! > > > flush stderr > > > > before any error. > > > Once this is verified, either write the outer handler at the C level > > > as suggested above, or in Tcl by wrapping your script in a [catch]. > > > > By the way, tclsh and wish both provide excellent outer handlers. > > > Are you sure you really want to embed, instead of extending Tcl ? > > > Please describe your situation. > > > > -Alex- Hide quoted text - > > > > - Show quoted text - > > > Thanks Alex, > > > Just, one more question. > > > In my application I want to send device commands through serial port. > > > Suppose I am sending device commands through tcl loop, how can i make > > tcl loop executes only as fast as my serial device can handle it? What > > I have observed is that tcl loop finished much faster then the device > > and data gets lost. > > The problem is not with the event loop, it has to do with low-level > flow control being enabled or not. When you [puts] to a channel in > Tcl, sonner or later a write() syscall will occur. For a socket, pipe, > or file, you have a stream semantics, in that no data is lost: the > write is done either in blocking or nonblocking mode, but in the > latter case data not immediately writte are retried later. > > For a serial port, if flow control is enabled, it should work the > same. But maybe this requires the physical device on the other side to > cooperate... > > Now you didn't answer *my* question ;-) > > -Alex- Hide quoted text - > > - Show quoted text - thanks again Alex, In my situations i am trying to provide tcl support to a MFC application, hence thinking of embedding and not extending. I hope i am not wrong ;-) Regards, Sandy |