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| author | dkf <donal.k.fellows@manchester.ac.uk> | 2009-03-19 16:14:38 (GMT) |
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| committer | dkf <donal.k.fellows@manchester.ac.uk> | 2009-03-19 16:14:38 (GMT) |
| commit | e77ab61acdd95f64d2222c71c72f2b2db1a39f65 (patch) | |
| tree | b84994282b432a0c5746273b4c2b06b0386b44cd | |
| parent | 538c2afa4a7741c3a8a459feb9c27f13848b9e7b (diff) | |
| download | tcl-e77ab61acdd95f64d2222c71c72f2b2db1a39f65.zip tcl-e77ab61acdd95f64d2222c71c72f2b2db1a39f65.tar.gz tcl-e77ab61acdd95f64d2222c71c72f2b2db1a39f65.tar.bz2 | |
Added documentation for tailcall.
| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | doc/tailcall.n | 69 |
2 files changed, 73 insertions, 0 deletions
@@ -1,3 +1,7 @@ +2009-03-19 Donal K. Fellows <dkf@users.sf.net> + + * doc/tailcall.n: Added documentation for tailcall command. + 2009-03-18 Don Porter <dgp@users.sourceforge.net> * win/tclWinFile.c (TclpObjNormalizePath): Corrected Tcl_Obj leak. diff --git a/doc/tailcall.n b/doc/tailcall.n new file mode 100644 index 0000000..2f8a305 --- /dev/null +++ b/doc/tailcall.n @@ -0,0 +1,69 @@ +'\" +'\" Copyright (c) 1993 The Regents of the University of California. +'\" Copyright (c) 1994-1996 Sun Microsystems, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" RCS: @(#) $Id: tailcall.n,v 1.1 2009/03/19 16:14:52 dkf Exp $ +'\" +.so man.macros +.TH tailcall n 8.6 Tcl "Tcl Built-In Commands" +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +tailcall \- Replace the current procedure with another command +.SH SYNOPSIS +\fBtailcall \fIcommand\fR ?\fIarg ...\fR? +.BE +.SH DESCRIPTION +.PP +The \fBtailcall\fR command replaces the currently executing procedure, lambda +application, or method with another command. The \fIcommand\fR, which will +have \fIarg ...\fR passed as arguments if they are supplied, will be looked up +in the current namespace context, not in the caller's. Apart from that +difference in resolution, it is equivalent to: +.PP +.CS +uplevel 1 [list \fIcommand\fR ?\fIarg ...\fR?] +.CE +.PP +This command may not be invoked from within an \fBuplevel\fR into a procedure. +.SH EXAMPLE +.PP +Compute the factorial of a number. +.PP +.CS +proc factorial {n {accum 1}} { + if {$n < 2} { + return $accum + } + \fBtailcall\fR factorial [expr {$n - 1}] [expr {$accum * $n}] +} +.CE +.PP +Print the elements of a list with alternating lines having different +indentations. +.PP +.CS +proc printList {theList} { + if {[llength $theList]} { + puts "> [lindex $theList 0]" + \fBtailcall\fR printList2 [lrange $theList 1 end] + } +} +proc printList2 {theList} { + if {[llength $theList]} { + puts "< [lindex $theList 0]" + \fBtailcall\fR printList [lrange $theList 1 end] + } +} +.CE +.SH "SEE ALSO" +apply(n), proc(n), uplevel(n) +.SH KEYWORDS +call, recursion, tail recursion +'\" Local Variables: +'\" mode: nroff +'\" fill-column: 78 +'\" End: |