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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_word-BreakAfter, tcl_wordBreakAfter,
       BreakAfter, 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
       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 appli-cation application
       cation will normally have its own library of support  procedures  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 command
              source [file join [info library] init.tcl]
       If  the  library procedure Tcl_Init is invoked from an application's Tcl_AppInit procedure, this hap-pens happens
       pens 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 directo-ries directories
              ries 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 direc-tories directories
              tories 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 infor-mation. information.
              mation.

       auto_import pattern
              Auto_import  is  invoked  during namespace import to see if the imported commands specified by
              pattern reside in an autoloaded library.  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  evaluate 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 successfully cre-ated. created.
              ated.  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  informa-tion information
              tion  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), gen-erates generates
              erates 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 unsophisticated way:  if any line con-tains contains
              tains 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
              namespace,  and  then in the global namespace.  Accordingly, if command is relative and names-pace namespace
              pace is not ::, the list returned has two elements:  command scoped by  namespace,  as  if  it
              were  a  command 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  run-time. runtime.
              time.

       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 basenameversion (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 environment 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 parallel build tree.

       parray arrayName
              Prints  on  standard  output  the names and values of all the elements in the array arrayName.
              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 fol-lowing following
              lowing  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_nonwordchars  below for more details on how Tcl determines which characters are word char-acters. characters.
              acters.

       tcl_startOfNextWord str start
              Returns the index of the first start-of-word location that occurs after a starting index start
              in the string str.  A start-of-word location is defined to be the first word character follow-ing following
              ing 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 occurs 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 bound-ary. boundary.
              ary.

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  particular  commands  exist  as  exe-cutable executable
              cutable 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 initialized during startup to contain, in order: the directories
              listed  in  the TCLLIBPATH environment variable, the directory named by the $tcl_library vari-able, variable,
              able, the parent directory of $tcl_library, the directories listed in the  $tcl_pkgPath  vari-able. variable.
              able.

       env(TCL_LIBRARY)
              If  set, then it specifies the location of the directory containing library scripts (the value
              of this variable will be assigned to the tcl_library variable and therefore  returned  by  the
              command 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,
              regardless  of platform.  This variable is only used when initializing the auto_path variable.

       tcl_nonwordchars
              This variable contains a regular expression that is used by  routines  like  tcl_endOfWord  to
              identify  whether  a  character is part of a word or not.  If the pattern matches a character,
              the character 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 underscores are considered non-word characters.

       tcl_wordchars
              This variable contains a regular expression that is used by  routines  like  tcl_endOfWord  to
              identify  whether  a  character is part of a word or not.  If the pattern matches a character,
              the character is considered to be a word character.  On Windows platforms, 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)