library (n)
standard library of Tcl procedures
SYNOPSIS
auto_execok cmd
auto_load cmd
auto_mkindex dir pattern pattern ...
auto_mkindex_old dir pattern pattern ...
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 application 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 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 by the name cmd.
This command examines the directories in the current search path
(given by the PATH environment variable) to see if there is an
executable file named cmd in any of those directories.
If so, it returns 1; if not it returns 0. Auto_exec
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_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
created.
The command returns 0 if there was no index entry for cmd
or if the script didn't 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
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 init.tcl to see how this works.
Auto_mkindex_old parses the Tcl scripts in a relatively
unsophisticated 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 don't appear in this way (e.g. they
have spaces before the proc) will not be indexed.
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're used.
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 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_nonwordchars below
for more details on how Tcl determines which characters are word
characters.
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
following 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
boundary.
VARIABLES
KEYWORDS
auto-exec, auto-load, library, unknown, word, whitespace
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