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Diffstat (limited to 'tcl/doc/CrtCommand.3')
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diff --git a/tcl/doc/CrtCommand.3 b/tcl/doc/CrtCommand.3 new file mode 100644 index 00000000000..a2946854ac3 --- /dev/null +++ b/tcl/doc/CrtCommand.3 @@ -0,0 +1,143 @@ +'\" +'\" Copyright (c) 1989-1993 The Regents of the University of California. +'\" Copyright (c) 1994-1997 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: @(#) $Id$ +'\" +.so man.macros +.TH Tcl_CreateCommand 3 "" Tcl "Tcl Library Procedures" +.BS +.SH NAME +Tcl_CreateCommand \- implement new commands in C +.SH SYNOPSIS +.nf +\fB#include <tcl.h>\fR +.sp +Tcl_Command +\fBTcl_CreateCommand\fR(\fIinterp, cmdName, proc, clientData, deleteProc\fR) +.SH ARGUMENTS +.AS Tcl_CmdDeleteProc **deleteProcPtr +.AP Tcl_Interp *interp in +Interpreter in which to create new command. +.AP char *cmdName in +Name of command. +.AP Tcl_CmdProc *proc in +Implementation of new command: \fIproc\fR will be called whenever +\fIcmdName\fR is invoked as a command. +.AP ClientData clientData in +Arbitrary one-word value to pass to \fIproc\fR and \fIdeleteProc\fR. +.AP Tcl_CmdDeleteProc *deleteProc in +Procedure to call before \fIcmdName\fR is deleted from the interpreter; +allows for command-specific cleanup. If NULL, then no procedure is +called before the command is deleted. +.BE + +.SH DESCRIPTION +.PP +\fBTcl_CreateCommand\fR defines a new command in \fIinterp\fR and associates +it with procedure \fIproc\fR such that whenever \fIcmdName\fR is +invoked as a Tcl command (via a call to \fBTcl_Eval\fR) the Tcl interpreter +will call \fIproc\fR to process the command. +It differs from \fBTcl_CreateObjCommand\fR in that a new string-based +command is defined; +that is, a command procedure is defined that takes an array of +argument strings instead of objects. +The object-based command procedures registered by \fBTcl_CreateObjCommand\fR +can execute significantly faster than the string-based command procedures +defined by \fBTcl_CreateCommand\fR. +This is because they take Tcl objects as arguments +and those objects can retain an internal representation that +can be manipulated more efficiently. +Also, Tcl's interpreter now uses objects internally. +In order to invoke a string-based command procedure +registered by \fBTcl_CreateCommand\fR, +it must generate and fetch a string representation +from each argument object before the call +and create a new Tcl object to hold the string result returned by the +string-based command procedure. +New commands should be defined using \fBTcl_CreateObjCommand\fR. +We support \fBTcl_CreateCommand\fR for backwards compatibility. +.PP +The procedures \fBTcl_DeleteCommand\fR, \fBTcl_GetCommandInfo\fR, +and \fBTcl_SetCommandInfo\fR are used in conjunction with +\fBTcl_CreateCommand\fR. +.PP +\fBTcl_CreateCommand\fR will delete an existing command \fIcmdName\fR, +if one is already associated with the interpreter. +It returns a token that may be used to refer +to the command in subsequent calls to \fBTcl_GetCommandName\fR. +If \fIcmdName\fR contains any \fB::\fR namespace qualifiers, +then the command is added to the specified namespace; +otherwise the command is added to the global namespace. +If \fBTcl_CreateCommand\fR is called for an interpreter that is in +the process of being deleted, then it does not create a new command +and it returns NULL. +\fIProc\fR should have arguments and result that match the type +\fBTcl_CmdProc\fR: +.CS +typedef int Tcl_CmdProc( + ClientData \fIclientData\fR, + Tcl_Interp *\fIinterp\fR, + int \fIargc\fR, + char *\fIargv\fR[]); +.CE +When \fIproc\fR is invoked the \fIclientData\fR and \fIinterp\fR +parameters will be copies of the \fIclientData\fR and \fIinterp\fR +arguments given to \fBTcl_CreateCommand\fR. +Typically, \fIclientData\fR points to an application-specific +data structure that describes what to do when the command procedure +is invoked. \fIArgc\fR and \fIargv\fR describe the arguments to +the command, \fIargc\fR giving the number of arguments (including +the command name) and \fIargv\fR giving the values of the arguments +as strings. The \fIargv\fR array will contain \fIargc\fR+1 values; +the first \fIargc\fR values point to the argument strings, and the +last value is NULL. +.VS +Note that the argument strings should not be modified as they may +point to constant strings or may be shared with other parts of the +interpreter. +.VE +.PP +\fIProc\fR must return an integer code that is either \fBTCL_OK\fR, \fBTCL_ERROR\fR, +\fBTCL_RETURN\fR, \fBTCL_BREAK\fR, or \fBTCL_CONTINUE\fR. See the Tcl overview man page +for details on what these codes mean. Most normal commands will only +return \fBTCL_OK\fR or \fBTCL_ERROR\fR. In addition, \fIproc\fR must set +the interpreter result to point to a string value; +in the case of a \fBTCL_OK\fR return code this gives the result +of the command, and in the case of \fBTCL_ERROR\fR it gives an error message. +The \fBTcl_SetResult\fR procedure provides an easy interface for setting +the return value; for complete details on how the the interpreter result +field is managed, see the \fBTcl_Interp\fR man page. +Before invoking a command procedure, +\fBTcl_Eval\fR sets the interpreter result to point to an empty string, +so simple commands can return an empty result by doing nothing at all. +.PP +The contents of the \fIargv\fR array belong to Tcl and are not +guaranteed to persist once \fIproc\fR returns: \fIproc\fR should +not modify them, nor should it set the interpreter result to point +anywhere within the \fIargv\fR values. +Call \fBTcl_SetResult\fR with status \fBTCL_VOLATILE\fR if you want +to return something from the \fIargv\fR array. +.PP +\fIDeleteProc\fR will be invoked when (if) \fIcmdName\fR is deleted. +This can occur through a call to \fBTcl_DeleteCommand\fR or \fBTcl_DeleteInterp\fR, +or by replacing \fIcmdName\fR in another call to \fBTcl_CreateCommand\fR. +\fIDeleteProc\fR is invoked before the command is deleted, and gives the +application an opportunity to release any structures associated +with the command. \fIDeleteProc\fR should have arguments and +result that match the type \fBTcl_CmdDeleteProc\fR: +.CS +typedef void Tcl_CmdDeleteProc(ClientData \fIclientData\fR); +.CE +The \fIclientData\fR argument will be the same as the \fIclientData\fR +argument passed to \fBTcl_CreateCommand\fR. +.PP + +.SH "SEE ALSO" +Tcl_CreateObjCommand, Tcl_DeleteCommand, Tcl_GetCommandInfo, Tcl_SetCommandInfo, Tcl_GetCommandName, Tcl_SetObjResult + +.SH KEYWORDS +bind, command, create, delete, interpreter, namespace |