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Diffstat (limited to 'doc/proc.n')
| -rw-r--r-- | doc/proc.n | 53 |
1 files changed, 33 insertions, 20 deletions
@@ -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: proc.n,v 1.5 2004/10/27 14:24:37 dkf Exp $ -'\" -.so man.macros .TH proc 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 @@ proc \- Create a Tcl procedure .SH SYNOPSIS \fBproc \fIname args body\fR .BE - .SH DESCRIPTION .PP The \fBproc\fR command creates a new Tcl procedure named @@ -35,20 +32,28 @@ elements specifies one argument. Each argument specifier is also a list with either one or two fields. If there is only a single field in the specifier then it is the name of the argument; if there are two fields, then -the first is the argument name and the second is its default value. +the first is the argument name and the second is its default value. +Arguments with default values that are followed by non-defaulted +arguments become required arguments. In 8.6 this will be considered an +error. .PP When \fIname\fR is invoked a local variable will be created for each of the formal arguments to the procedure; its value will be the value of corresponding argument in the invoking command or the argument's default value. +Actual arguments are assigned to formal arguments strictly in order. Arguments with default values need not be specified in a procedure invocation. However, there must be enough actual arguments for all the -formal arguments that don't have defaults, and there must not be any extra -actual arguments. There is one special case to permit procedures with +formal arguments that do not have defaults, and there must not be any extra +actual arguments. +Arguments with default values that are followed by non-defaulted +arguments become required arguments (in 8.6 it will be considered an +error). +There is one special case to permit procedures with variable numbers of arguments. If the last formal argument has the name \fBargs\fR, then a call to the procedure may contain more actual arguments -than the procedure has formals. In this case, all of the actual arguments +than the procedure has formal arguments. In this case, all of the actual arguments starting at the one that would be assigned to \fBargs\fR are combined into a list (as if the \fBlist\fR command had been used); this combined value is assigned to the local variable \fBargs\fR. @@ -57,41 +62,49 @@ When \fIbody\fR is being executed, variable names normally refer to local variables, which are created automatically when referenced and deleted when the procedure returns. One local variable is automatically created for each of the procedure's arguments. -Global variables can only be accessed by invoking -the \fBglobal\fR command or the \fBupvar\fR command. -Namespace variables can only be accessed by invoking -the \fBvariable\fR command or the \fBupvar\fR command. +Other variables can only be accessed by invoking one of the \fBglobal\fR, +\fBvariable\fR, \fBupvar\fR or \fBnamespace upvar\fR commands. +The current namespace when \fIbody\fR is executed will be the +namespace that the procedure's name exists in, which will be the +namespace that it was created in unless it has been changed with +\fBrename\fR. +'\" We may change this! It makes [variable] unstable when renamed and is +'\" frankly pretty crazy, but doing it right is harder than it looks. .PP The \fBproc\fR command returns an empty string. When a procedure is invoked, the procedure's return value is the value specified in a -\fBreturn\fR command. If the procedure doesn't execute an explicit +\fBreturn\fR command. If the procedure does not execute an explicit \fBreturn\fR, then its return value is the value of the last command executed in the procedure's body. If an error occurs while executing the procedure body, then the procedure-as-a-whole will return that same error. .SH EXAMPLES +.PP This is a procedure that accepts arbitrarily many arguments and prints them out, one by one. +.PP .CS \fBproc\fR printArguments args { - foreach arg $args { - puts $arg - } + foreach arg $args { + puts $arg + } } .CE .PP This procedure is a bit like the \fBincr\fR command, except it multiplies the contents of the named variable by the value, which defaults to \fB2\fR: +.PP .CS \fBproc\fR mult {varName {multiplier 2}} { - upvar 1 $varName var - set var [expr {$var * $multiplier}] + upvar 1 $varName var + set var [expr {$var * $multiplier}] } .CE - .SH "SEE ALSO" info(n), unknown(n) - .SH KEYWORDS argument, procedure +'\" Local Variables: +'\" mode: nroff +'\" End: |