diff options
Diffstat (limited to 'doc/uplevel.n')
| -rw-r--r-- | doc/uplevel.n | 27 |
1 files changed, 15 insertions, 12 deletions
diff --git a/doc/uplevel.n b/doc/uplevel.n index ee4f6c7..a96f729 100644 --- a/doc/uplevel.n +++ b/doc/uplevel.n @@ -5,10 +5,8 @@ '\" See the file "license.terms" for information on usage and redistribution '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. '\" -'\" RCS: @(#) $Id: uplevel.n,v 1.5 2004/10/27 14:43:54 dkf Exp $ -'\" -.so man.macros .TH uplevel n "" Tcl "Tcl Built-In Commands" +.so man.macros .BS '\" Note: do not modify the .SH NAME line immediately below! .SH NAME @@ -16,7 +14,6 @@ uplevel \- Execute a script in a different stack frame .SH SYNOPSIS \fBuplevel \fR?\fIlevel\fR?\fI arg \fR?\fIarg ...\fR? .BE - .SH DESCRIPTION .PP All of the \fIarg\fR arguments are concatenated as if they had @@ -43,28 +40,32 @@ at top-level (only global variables will be visible). The \fBuplevel\fR command causes the invoking procedure to disappear from the procedure calling stack while the command is being executed. In the above example, suppose \fBc\fR invokes the command +.PP .CS \fBuplevel\fR 1 {set x 43; d} .CE +.PP where \fBd\fR is another Tcl procedure. The \fBset\fR command will modify the variable \fBx\fR in \fBb\fR's context, and \fBd\fR will execute at level 3, as if called from \fBb\fR. If it in turn executes the command +.PP .CS \fBuplevel\fR {set x 42} .CE +.PP then the \fBset\fR command will modify the same variable \fBx\fR in \fBb\fR's context: the procedure \fBc\fR does not appear to be on the call stack -when \fBd\fR is executing. The command ``\fBinfo level\fR'' may +when \fBd\fR is executing. The \fBinfo level\fR command may be used to obtain the level of the current procedure. .PP \fBUplevel\fR makes it possible to implement new control constructs as Tcl procedures (for example, \fBuplevel\fR could be used to implement the \fBwhile\fR construct as a Tcl procedure). .PP -\fBnamespace eval\fR is another way (besides procedure calls) -that the Tcl naming context can change. -It adds a call frame to the stack to represent the namespace context. +The \fBnamespace eval\fR and \fBapply\fR commands offer other ways +(besides procedure calls) that the Tcl naming context can change. +They add a call frame to the stack to represent the namespace context. This means each \fBnamespace eval\fR command counts as another call level for \fBuplevel\fR and \fBupvar\fR commands. For example, \fBinfo level 1\fR will return a list @@ -78,6 +79,7 @@ control constructs. This example shows how (without error handling) it can be used to create a \fBdo\fR command that is the counterpart of \fBwhile\fR except for always performing the test after running the loop body: +.PP .CS proc do {body while condition} { if {$while ne "while"} { @@ -92,9 +94,10 @@ proc do {body while condition} { } } .CE - .SH "SEE ALSO" -namespace(n), upvar(n) - +apply(n), namespace(n), upvar(n) .SH KEYWORDS -context, level, namespace, stack frame, variables +context, level, namespace, stack frame, variable +.\" Local Variables: +.\" mode: nroff +.\" End: |