diff options
Diffstat (limited to 'doc/error.n')
| -rw-r--r-- | doc/error.n | 48 |
1 files changed, 27 insertions, 21 deletions
diff --git a/doc/error.n b/doc/error.n index 8c47ba3..77391e5 100644 --- a/doc/error.n +++ b/doc/error.n @@ -21,36 +21,42 @@ Returns a \fBTCL_ERROR\fR code, which causes command interpretation to be unwound. \fIMessage\fR is a string that is returned to the application to indicate what went wrong. .PP -If the \fIinfo\fR argument is provided and is non-empty, -it is used to initialize the global variable \fBerrorInfo\fR. -\fBerrorInfo\fR is used to accumulate a stack trace of what -was in progress when an error occurred; as nested commands unwind, -the Tcl interpreter adds information to \fBerrorInfo\fR. If the -\fIinfo\fR argument is present, it is used to initialize -\fBerrorInfo\fR and the first increment of unwind information -will not be added by the Tcl interpreter. In other +The \fB\-errorinfo\fR return option of an interpreter is used +to accumulate a stack trace of what was in progress when an +error occurred; as nested commands unwind, +the Tcl interpreter adds information to the \fB\-errorinfo\fR +return option. If the \fIinfo\fR argument is present, it is +used to initialize the \fB\-errorinfo\fR return options and +the first increment of unwind information +will not be added by the Tcl interpreter. +In other words, the command containing the \fBerror\fR command will not appear -in \fBerrorInfo\fR; in its place will be \fIinfo\fR. -This feature is most useful in conjunction with the \fBcatch\fR command: +in the stack trace; in its place will be \fIinfo\fR. +Historically, this feature had been most useful in conjunction +with the \fBcatch\fR command: if a caught error cannot be handled successfully, \fIinfo\fR can be used to return a stack trace reflecting the original point of occurrence of the error: .CS \fBcatch {...} errMsg -set savedInfo $errorInfo +set savedInfo $::errorInfo \&... error $errMsg $savedInfo\fR .CE +When working with Tcl 8.5 or later, the following code +should be used instead: +.CS +\fBcatch {...} errMsg options +\&... +return -options $options $errMsg\fR +.CE .PP If the \fIcode\fR argument is present, then its value is stored -in the \fBerrorCode\fR global variable. This variable is intended -to hold a machine-readable description of the error in cases where -such information is available; see the \fBtclvars\fR manual -page for information on the proper format for the variable. -If the \fIcode\fR argument is not -present, then \fBerrorCode\fR is automatically reset to -``NONE'' by the Tcl interpreter as part of processing the -error generated by the command. +in the \fB\-errorcode\fR return option. The \fB\-errorcode\fR +return option is intended to hold a machine-readable description +of the error in cases where such information is available; see +the \fBreturn\fR manual page for information on the proper format +for this option's value. .SH EXAMPLE Generate an error if a basic mathematical operation fails: .CS @@ -60,7 +66,7 @@ if {1+2 != 3} { .CE .SH "SEE ALSO" -catch(n), return(n), tclvars(n) +catch(n), return(n) .SH KEYWORDS -error, errorCode, errorInfo +error |