NAME
auto_execok, auto_import, auto_load, auto_mkindex,
auto_mkindex_old, auto_qualify, auto_reset, tcl_findLi
brary, parray, tcl_endOfWord, tcl_startOfNextWord,
tcl_startOfPreviousWord, tcl_wordBreakAfter, tcl_word
BreakBefore - 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 differ
ent 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 applica
tion 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 automat
ically. The code in init.tcl will define the unknown pro
cedure 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:
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 Win
dows platforms, the search is expanded with the
same directories and file extensions as used by
exec. Auto_exec remembers information about previ
ous 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 imported commands specified by pattern
reside in an autoloaded library. If so, the com
mands 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.
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. Other
wise 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 gener
ated 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
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 com
mands 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 rela
tively 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. 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're used.
auto_qualify command namespace
Computes a list of fully qualified names for com
mand. 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 com
mand is relative and namespace is not ::, the list
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 runtime.
tcl_findLibrary basename version patch initScript
enVarName var Name
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 inter
preter once it is found. The directory in which
this file is found is stored into the global vari
able 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 par
ray. 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. |
start | |
Returns the index of the first start-of-word loca |
tion 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 loca |
tion 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
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 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.
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 giv
ing directories to search during auto-load opera
tions. 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 variable, the parent
directory of $tcl_library, the directories listed
in the $tcl_pkgPath variable.
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 isn't set then a
default value is used.
env(TCLLIBPATH)
If set, then it must contain a valid Tcl list giv
ing directories to search during auto-load opera
tions. Directories must be specified in Tcl for
mat, using "/" as the path separator, regardless 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 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 consid |
ered 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 under |
scores.
unknown_pending
Used by unknown to record the command(s) for which
unknown recurses on itself infinitely. The vari
able is unset before unknown returns.
SEE ALSO
info(n), re_syntax(n)
KEYWORDS
auto-exec, auto-load, library, unknown, word, whitespace
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