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Diffstat (limited to 'itcl/itcl/doc/body.n')
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1 files changed, 124 insertions, 0 deletions
diff --git a/itcl/itcl/doc/body.n b/itcl/itcl/doc/body.n new file mode 100644 index 00000000000..a01470140fe --- /dev/null +++ b/itcl/itcl/doc/body.n @@ -0,0 +1,124 @@ +'\" +'\" Copyright (c) 1993-1998 Lucent Technologies, Inc. +'\" +'\" See the file "license.terms" for information on usage and redistribution +'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES. +'\" +'\" RCS: $Id$ +'\" +.so man.macros +.TH body n 3.0 itcl "[incr\ Tcl]" +.BS +'\" Note: do not modify the .SH NAME line immediately below! +.SH NAME +body \- change the body for a class method/proc +.SH SYNOPSIS +\fBbody \fIclassName\fB::\fIfunction args body\fR +.BE + +.SH DESCRIPTION +.PP +The \fBbody\fR command is used outside of an \fB[incr\ Tcl]\fR +class definition to define or redefine the body of a class +method or proc. This facility allows a class definition +to have separate "interface" and "implementation" parts. +The "interface" part is a \fBclass\fR command with declarations +for methods, procs, instance variables and common variables. +The "implementation" part is a series of \fBbody\fR and +\fBconfigbody\fR commands. If the "implementation" part +is kept in a separate file, it can be sourced again and +again as bugs are fixed, to support interactive development. +When using the "tcl" mode in the \fBemacs\fR editor, the +"interface" and "implementation" parts can be kept in the +same file; as bugs are fixed, individual bodies can be +highlighted and sent to the test application. +.PP +The name "\fIclassName\fB::\fIfunction\fR" +identifies the method/proc being changed. +.PP +If an \fIargs\fR list was specified when the \fIfunction\fR was +defined in the class definition, the \fIargs\fR list for the +\fBbody\fR command must match in meaning. Variable names +can change, but the argument lists must have the same required +arguments and the same default values for optional arguments. +The special \fBargs\fR argument acts as a wildcard when included +in the \fIargs\fR list in the class definition; it will match +zero or more arguments of any type when the body is redefined. +.PP +If the \fIbody\fR string starts with "\fB@\fR", it is treated +as the symbolic name for a C procedure. The \fIargs\fR list +has little meaning for the C procedure, except to document +the expected usage. (The C procedure is not guaranteed to +use arguments in this manner.) If \fIbody\fR does not start +with "\fB@\fR", it is treated as a Tcl command script. When +the function is invoked, command line arguments are matched +against the \fIargs\fR list, and local variables are created +to represent each argument. This is the usual behavior for +a Tcl-style proc. +.PP +Symbolic names for C procedures are established by registering +procedures via \fBItcl_RegisterC()\fR. This is usually done +in the \fBTcl_AppInit()\fR procedure, which is automatically called +when the interpreter starts up. In the following example, +the procedure \fCMy_FooCmd()\fR is registered with the +symbolic name "foo". This procedure can be referenced in +the \fBbody\fR command as "\fC@foo\fR". +.CS +int +Tcl_AppInit(interp) + Tcl_Interp *interp; /* Interpreter for application. */ +{ + if (Itcl_Init(interp) == TCL_ERROR) { + return TCL_ERROR; + } + + if (Itcl_RegisterC(interp, "foo", My_FooCmd) != TCL_OK) { + return TCL_ERROR; + } +} +.CE + +.SH EXAMPLE +In the following example, a "File" class is defined to represent +open files. The method bodies are included below the class +definition via the \fBbody\fR command. Note that the bodies +of the constructor/destructor must be included in the class +definition, but they can be redefined via the \fBbody\fR command +as well. +.CS +class File { + private variable fid "" + constructor {name access} { + set fid [open $name $access] + } + destructor { + close $fid + } + + method get {} + method put {line} + method eof {} +} + +body File::get {} { + return [gets $fid] +} +body File::put {line} { + puts $fid $line +} +body File::eof {} { + return [::eof $fid] +} + +# +# See the File class in action: +# +File x /etc/passwd "r" +while {![x eof]} { + puts "=> [x get]" +} +delete object x +.CE + +.SH KEYWORDS +class, object, procedure |