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return puts "line 2" ;# This line will not be printed. } Next, an example of using return to set the value returned by the procedure. The procedure command behaves in its calling context as if it were the command return (with no arguments). The source command performs the same handling of the TCL_RETURN return code, which explains the similarity of return invocation during a source to return invocation within a procedure. What is Tk? have a peek here

In Tcl, a proc may return a value, but it always returns a status. However, unlike return, tailcall's continuation is not the caller. The return code of the return command itself triggers this special handling by procedure invocation. it's possible that a non-error situation in the script can give the return value of [catch] a value other than 0 for example, if you simply use a [return] to exit http://wiki.tcl.tk/1644

Tcl Error Command

Typically the info value is supplied from the value of -errorinfo in a return options dictionary captured by the catch command (or from the copy of that information stored in the Description editreturn creates an options dictionary which made available via catch and try. As documented above, the -code entry in the return options dictionary receives special treatment by Tcl. proc returnX {} {return X} puts [returnX] ;# prints "X" Next, a more complete example, using return -code error to report invalid arguments.

Theses failure codes are used as exit code of the C executable.Catching the close on the blocked command channel to the C executable let the exit code be stored in side The procedure command behaves in its calling context as if it were the command return (with no arguments). In Java, you can have a variety of exceptions, each represented by a different class, that signal different types of error conditions. Tcl Error Code Each procedure adds some information about the problem to the report.

The procedure command behaves in its calling context as if it were the command error result. When [lindex] is given only one argument, it interprets that as instruction to not perform any list indexing. Similarly, if a command expects a script, you'd better pass it a script.PYK 2013-12-10: However, if lindex is missing its second value, the first value can still be The recommendation frequently is to usecatch {exec somecommand &}However, what would be a strategy if you wanted to catch the output and somecommand's return code?HaO: Use open and a command pipe,

proc myBreak {} { return -code break } SEE ALSO break, catch, continue, error, proc, source, tclvars KEYWORDS break, catch, continue, error, procedure, return Copyright © 1993 The Regents of the Tcl Catch Exec An example is shown below − #!/usr/bin/tclsh catch {set file [open myNonexistingfile.txt]} result puts "ErrorMsg: $result" puts "ErrorCode: $errorCode" puts "ErrorInfo:\n$errorInfo\n" When the above code is executed, it produces the following If no -errorcode option is provided to return when the -code error option is provided, Tcl will set the value of the -errorcode entry in the return options dictionary to the But here is an example: # Attempt to catch the return code from f77 # set rc [catch { exec f77 -c myff2.f } msg ] set errc $errorCode; set erri

Tcl Error Handling

return (or 2) The return code of the procedure is 2 (TCL_RETURN). Continued All Rights Reserved. Tcl Error Command Incomplete and subject to change at short notice, but something is better than nothing. :-)trythrowreturnArts and crafts of Tcl-Tk programmingCategory Command HomeRecent changesHelpWhoAmI/LogoutCreate new pageRandom pagePrevious pageNext pageAdd commentsEditHistoryEdit summaryReferences Page Tcl Catch Example The following three commands all effectively instruct the caller to return normally from the current procedure (level 1):return return -level 0 -code return return -level 1 -code okThe return value is

If evaluation of the loop body returns the return code of TCL_BREAK or TCL_CONTINUE, the loop command can react in such a way as to give the break and continue commands navigate here By way of analogy: lindex interprets its first argument as a list, so you'd better only pass it valid lists. This behavior can lead to problems like this:# I've got an open socket whose handle's stored in fid catch { puts $fid "Here's my last message." close $fid } errIf the error message ?info? ?code? Tcl Errorinfo

finally ...KBK 2001-01-02: how to use return -code to implement a new control structure. The less common case is that a procedure implements a new control structure and needs act, within its caller, like break, continue, or error. In C, you would have received a NULL pointer, and without checking that, Segmentation Fault would be right around the corner. Check This Out The standard ARITH, CHILD*, NONE, and POSIX only cover a fraction of all possible error conditions.Tcl syntaxCategory Debugging HomeRecent changesHelpWhoAmI/LogoutCreate new pageRandom pagePrevious pageNext pageAdd commentsEditHistoryEdit summaryReferences Page contents SeeAlso Description

If varName is supplied, the value returned by script is placed in varName if the script successfully executes. Tcl Throw Error Error syntax error message info code In the above error command syntax, message is the error message, info is set in the global variable errorInfo and code is set in the DESCRIPTION In its simplest usage, the return command is used without options in the body of a procedure to immediately return control to the caller of the procedure.

No list indexing means no requirement to be a list.

In Tcl, they're like "little friends" - helpful (explaining the problem), not messing up everything (as a Segmentation Fault/Bus Error/Divide by Zero would do). Early throw Discussion editThe following discussion was held before Tcl 8.6 added try/throw:throw: The logical opposite to catching is throwing. See below for additional options. Tcl Try Catch Example In either case, a message will be placed in errorInfo, and the proc will generate an error.

Typically the list value is supplied from the value of -errorstack in a return options dictionary captured by the catch command (or from the copy of that information from info errorstack). go

When -level is 0, the default value of -code is return. http://colinmeldrum.com/tcl-error/tcl-error-out.html In other words, it needs return -level 1 ...

When source evaluates the contents of a file as a script, an invocation of the return command will cause script evaluation to immediately cease, and the value result (or an empty return -level 1 -code ok is the same as return. (TCL_OK)1errorAn error. break (or 3) The return code of the procedure is 3 (TCL_BREAK). break (3) The return code of the procedure is 3 (TCL_BREAK).

They are described in extenso in the man page on tclvars. Pretty natural, no? In the releases in between, due to some limitations in the bytecode compiler/execution machinery it could not be "whatever":braces still needed to be balancedCommands like set get byte-compiled early, so a EXAMPLES First, a simple example of using return to return from a procedure, interrupting the procedure body.