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library(n)		     Tcl Built-In Commands		    library(n)

______________________________________________________________________________

NAME
       auto_execok,  auto_import,  auto_load,  auto_mkindex, auto_mkindex_old,
       auto_qualify,  auto_reset,  tcl_findLibrary,   parray,	tcl_endOfWord,
       tcl_startOfNextWord,    tcl_startOfPreviousWord,	   tcl_wordBreakAfter,
       tcl_wordBreakBefore - standard library of Tcl procedures

SYNOPSIS
       auto_execok cmd
       auto_import pattern
       auto_load cmd
       auto_mkindex dir	pattern	pattern	...
       auto_mkindex_old	dir pattern pattern ...
       auto_qualify command namespace
       auto_reset
       tcl_findLibrary basename	version	patch initScript enVarName varName
       parray arrayName	?pattern?
       tcl_endOfWord str start
       tcl_startOfNextWord str start
       tcl_startOfPreviousWord str start
       tcl_wordBreakAfter str start
       tcl_wordBreakBefore str start
______________________________________________________________________________

INTRODUCTION
       Tcl includes a library of Tcl procedures	for commonly-needed functions.
       The procedures defined in the Tcl library are generic ones suitable for
       use by many different applications.  The	location of the	Tcl library is
       returned	 by the	info library command.  In addition to the Tcl library,
       each application	will normally have its own library of  support	proce-
       dures  as  well;	 the location of this library is normally given	by the
       value of	the $app_library global	variable, where	app is the name	of the
       application.   For  example,  the location of the Tk library is kept in
       the variable $tk_library.

       To access the procedures	in the	Tcl  library,  an  application	should
       source  the file	init.tcl in the	library, for example with the Tcl com-
       mand
	      source [file join	[info library] init.tcl]
       If the library procedure	Tcl_Init  is  invoked  from  an	 application's
       Tcl_AppInit   procedure,	 this  happens	automatically.	 The  code  in
       init.tcl	will define the	unknown	procedure and arrange  for  the	 other
       procedures to be	loaded on-demand using the auto-load mechanism defined
       below.

COMMAND	PROCEDURES
       The following procedures	are provided in	the Tcl	library:

       auto_execok cmd
	      Determines whether there is an executable	file or	shell  builtin
	      by  the  name  cmd.  If so, it returns a list of arguments to be
	      passed to	exec to	execute	the executable file or	shell  builtin
	      named by cmd.  If	not, it	returns	an empty string.  This command
	      examines the directories in the current search  path  (given  by
	      the  PATH	 environment variable) in its search for an executable
	      file named cmd.  On Windows platforms, the  search  is  expanded
	      with  the	 same directories and file extensions as used by exec.
	      Auto_execok remembers information	about previous searches	in  an
	      array  named  auto_execs;	 this avoids the path search in	future
	      calls for	the same cmd.  The command auto_reset may be  used  to
	      force auto_execok	to forget its cached information.

       auto_import pattern
	      Auto_import is invoked during namespace import to	see if the im-
	      ported commands specified	by pattern reside in an	autoloaded li-
	      brary.   If  so,	the  commands  are loaded so that they will be
	      available	to the interpreter for creating	the import links.   If
	      the commands do not reside in an autoloaded library, auto_import
	      does nothing.  The pattern matching is  performed	 according  to
	      the matching rules of namespace import.

       auto_load cmd
	      This  command  attempts to load the definition for a Tcl command
	      named cmd.  To do	this, it searches an auto-load path, which  is
	      a	 list of one or	more directories.  The auto-load path is given
	      by the global variable $auto_path	if it exists.  If there	is  no
	      $auto_path variable, then	the TCLLIBPATH environment variable is
	      used, if it exists.  Otherwise the auto-load  path  consists  of
	      just  the	 Tcl  library directory.  Within each directory	in the
	      auto-load	path there must	be a file tclIndex that	describes  one
	      or more commands defined in that directory and a script to eval-
	      uate to load each	of the commands.  The tclIndex file should  be
	      generated	 with the auto_mkindex command.	 If cmd	is found in an
	      index file, then the appropriate script is evaluated  to	create
	      the  command.   The  auto_load command returns 1 if cmd was suc-
	      cessfully	created.  The command returns 0	if there was no	 index
	      entry for	cmd or if the script did not actually define cmd (e.g.
	      because index information	is out of date).  If an	 error	occurs
	      while  processing	 the  script,  then  that  error  is returned.
	      Auto_load	only reads the index information once and saves	it  in
	      the  array  auto_index;  future calls to auto_load check for cmd
	      in the array rather than re-reading the index files.  The	cached
	      index  information  may  be deleted with the command auto_reset.
	      This will	force the next auto_load command to reload  the	 index
	      database from disk.

       auto_mkindex dir	pattern	pattern	...
	      Generates	 an  index suitable for	use by auto_load.  The command
	      searches dir for all files whose names match any of the  pattern
	      arguments	(matching is done with the glob	command), generates an
	      index of all the Tcl  command  procedures	 defined  in  all  the
	      matching files, and stores the index information in a file named
	      tclIndex in dir. If no pattern is	given a	pattern	of *.tcl  will
	      be assumed.  For example,	the command
		     auto_mkindex foo *.tcl

	      will  read all the .tcl files in subdirectory foo	and generate a
	      new index	file foo/tclIndex.

	      Auto_mkindex parses the Tcl scripts  by  sourcing	 them  into  a
	      slave interpreter	and monitoring the proc	and namespace commands
	      that  are	 executed.   Extensions	 can  use  the	(undocumented)
	      auto_mkindex_parser  package to register other commands that can
	      contribute to the	auto_load index. You will have to read through
	      auto.tcl to see how this works.

	      Auto_mkindex_old	parses	the  Tcl scripts in a relatively unso-
	      phisticated way:	if any line contains  the  word	 proc  as  its
	      first characters then it is assumed to be	a procedure definition
	      and the next word	of the line is taken as	the procedure's	 name.
	      Procedure	 definitions that do not appear	in this	way (e.g. they
	      have spaces before the proc)  will  not  be  indexed.   If  your
	      script  contains "dangerous" code, such as global	initialization
	      code or procedure	names with special characters like $, *, [  or
	      ], you are safer using auto_mkindex_old.

       auto_reset
	      Destroys	 all   the   information  cached  by  auto_execok  and
	      auto_load.  This information will	be re-read from	disk the  next
	      time  it	is  needed.   Auto_reset  also	deletes	any procedures
	      listed in	the auto-load index, so	that fresh copies of them will
	      be loaded	the next time that they	are used.

       auto_qualify command namespace
	      Computes a list of fully qualified names for command.  This list
	      mirrors the path a standard Tcl interpreter follows for  command
	      lookups:	 first	it  looks for the command in the current name-
	      space, and then in the global namespace.	Accordingly,  if  com-
	      mand  is relative	and namespace is not ::, the list returned has
	      two elements:  command scoped by namespace, as if	it were	a com-
	      mand  in	the  namespace	namespace; and command as if it	were a
	      command in the global namespace.	Otherwise, if  either  command
	      is  absolute  (it	 begins	with ::), or namespace is ::, the list
	      contains only command as if it were  a  command  in  the	global
	      namespace.

	      Auto_qualify is used by the auto-loading facilities in Tcl, both
	      for producing auto-loading indexes such as pkgIndex.tcl, and for
	      performing the actual auto-loading of functions at runtime.

       tcl_findLibrary basename	version	patch initScript enVarName varName
	      This is a	standard search	procedure for use by extensions	during
	      their initialization.  They call	this  procedure	 to  look  for
	      their  script library in several standard	directories.  The last
	      component	of the name of the library directory is	normally base-
	      nameversion (e.g., tk8.0), but it	might be "library" when	in the
	      build hierarchies.  The initScript file will be sourced into the
	      interpreter  once	it is found.  The directory in which this file
	      is found is stored into the global variable  varName.   If  this
	      variable	is already defined (e.g., by C code during application
	      initialization) then no searching	is done.  Otherwise the	search
	      looks  in	these directories: the directory named by the environ-
	      ment variable enVarName; relative	to the Tcl library  directory;
	      relative to the executable file in the standard installation bin
	      or bin/arch directory; relative to the executable	 file  in  the
	      current  build tree; relative to the executable file in a	paral-
	      lel build	tree.

       parray arrayName	?pattern?
	      Prints on	standard output	the names and values of	all  the  ele-
	      ments  in	the array arrayName, or	just the names that match pat-
	      tern (using the matching rules of	string match) and their	values
	      if  pattern  is given.  ArrayName	must be	an array accessible to
	      the caller of parray.  It	may be either local or global.

       tcl_endOfWord str start
	      Returns the index	of the first end-of-word location that	occurs
	      after  a starting	index start in the string str.	An end-of-word
	      location is defined to be	the first non-word character following
	      the  first  word character after the starting point.  Returns -1
	      if there are no more end-of-word locations  after	 the  starting
	      point.   See  the	 description of	tcl_wordchars and tcl_nonword-
	      chars below for more details on how Tcl determines which charac-
	      ters are word characters.

       tcl_startOfNextWord str start
	      Returns  the  index of the first start-of-word location that oc-
	      curs after a starting index start	in the string str.   A	start-
	      of-word  location	is defined to be the first word	character fol-
	      lowing a non-word	character.  Returns -1 if there	 are  no  more
	      start-of-word locations after the	starting point.

       tcl_startOfPreviousWord str start
	      Returns  the  index of the first start-of-word location that oc-
	      curs before a starting index start in the	string	str.   Returns
	      -1  if  there  are  no  more  start-of-word locations before the
	      starting point.

       tcl_wordBreakAfter str start
	      Returns the index	of the first word boundary after the  starting
	      index  start in the string str.  Returns -1 if there are no more
	      boundaries after the starting point in the  given	 string.   The
	      index  returned  refers to the second character of the pair that
	      comprises	a boundary.

       tcl_wordBreakBefore str start
	      Returns the index	of the first word boundary before the starting
	      index  start in the string str.  Returns -1 if there are no more
	      boundaries before	the starting point in the given	 string.   The
	      index  returned  refers to the second character of the pair that
	      comprises	a boundary.

VARIABLES
       The following global variables are defined or used by the procedures in
       the Tcl library:

       auto_execs
	      Used by auto_execok to record information	about whether particu-
	      lar commands exist as executable files.

       auto_index
	      Used by auto_load	to save	the index information read from	disk.

       auto_noexec
	      If set to	any value, then	unknown	will not attempt to  auto-exec
	      any commands.

       auto_noload
	      If  set to any value, then unknown will not attempt to auto-load
	      any commands.

       auto_path
	      If set, then it must contain a valid Tcl list giving directories
	      to  search  during  auto-load operations.	 This variable is ini-
	      tialized during startup to contain, in  order:  the  directories
	      listed  in  the  TCLLIBPATH  environment variable, the directory
	      named by the $tcl_library	 variable,  the	 parent	 directory  of
	      $tcl_library,  the  directories listed in	the $tcl_pkgPath vari-
	      able.

       env(TCL_LIBRARY)
	      If set, then it specifies	the location of	the directory contain-
	      ing library scripts (the value of	this variable will be assigned
	      to the tcl_library variable and therefore	returned by  the  com-
	      mand  info library).  If this variable is	not set	then a default
	      value is used.

       env(TCLLIBPATH)
	      If set, then it must contain a valid Tcl list giving directories
	      to  search  during  auto-load  operations.   Directories must be
	      specified	in Tcl format, using "/" as the	 path  separator,  re-
	      gardless	of platform.  This variable is only used when initial-
	      izing the	auto_path variable.

       tcl_nonwordchars
	      This variable contains a regular expression that is used by rou-
	      tines like tcl_endOfWord to identify whether a character is part
	      of a word	or not.	 If the	pattern	matches	a character, the char-
	      acter  is	 considered  to	 be  a non-word	character.  On Windows
	      platforms, spaces, tabs, and newlines  are  considered  non-word
	      characters.  Under Unix, everything but numbers, letters and un-
	      derscores	are considered non-word	characters.

       tcl_wordchars
	      This variable contains a regular expression that is used by rou-
	      tines like tcl_endOfWord to identify whether a character is part
	      of a word	or not.	 If the	pattern	matches	a character, the char-
	      acter  is	 considered  to	be a word character.  On Windows plat-
	      forms, words are comprised of any	character that is not a	space,
	      tab,  or	newline.   Under Unix, words are comprised of numbers,
	      letters or underscores.

SEE ALSO
       info(n),	re_syntax(n)

KEYWORDS
       auto-exec, auto-load, library, unknown, word, whitespace

Tcl				      8.0			    library(n)

NAME | SYNOPSIS | INTRODUCTION | COMMAND PROCEDURES | VARIABLES | SEE ALSO | KEYWORDS

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