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.so man.macros

.TH library n "8.0" Tcl "Tcl Built-In Commands"

.BS

.SH NAME

library \- standard library of Tcl procedures

.SH SYNOPSIS

.nf

\fBauto_execok \fIcmd\fR

\fBauto_load \fIcmd\fR

\fBauto_mkindex \fIdir pattern pattern ...\fR

\fBauto_mkindex_old \fIdir pattern pattern ...\fR

\fBauto_reset\fR

\fBtcl_findLibrary \fIbasename version patch initScript enVarName varName\fR

\fBparray \fIarrayName\fR

.VS

\fBtcl_endOfWord \fIstr start\fR

\fBtcl_startOfNextWord \fIstr start\fR

\fBtcl_startOfPreviousWord \fIstr start\fR

\fBtcl_wordBreakAfter \fIstr start\fR

\fBtcl_wordBreakBefore \fIstr start\fR

.VE

.BE

.SH INTRODUCTION

.PP

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 \fBinfo library\fR

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 \fB$\fIapp\fB_library\fR

global variable, where \fIapp\fR is the name of the application.

For example, the location of the Tk library is kept in the variable

\fB$tk_library\fR.

.PP

To access the procedures in the Tcl library, an application should

source the file \fBinit.tcl\fR in the library, for example with

the Tcl command

.CS

\fBsource [file join [info library] init.tcl]\fR

.CE

If the library procedure \fBTcl_Init\fR is invoked from an application's

\fBTcl_AppInit\fR procedure, this happens automatically.

The code in \fBinit.tcl\fR will define the \fBunknown\fR procedure

and arrange for the other procedures to be loaded on-demand using

the auto-load mechanism defined below.

.SH "COMMAND PROCEDURES"

.PP

The following procedures are provided in the Tcl library:

.TP

\fBauto_execok \fIcmd\fR

Determines whether there is an executable file by the name \fIcmd\fR.

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 \fIcmd\fR in any of those directories.

If so, it returns 1;  if not it returns 0.  \fBAuto_exec\fR

remembers information about previous searches in an array

named \fBauto_execs\fR;  this avoids the path search in

future calls for the same \fIcmd\fR.  The command \fBauto_reset\fR

may be used to force \fBauto_execok\fR to forget its cached

information.

.TP

\fBauto_load \fIcmd\fR

This command attempts to load the definition for a Tcl command named

\fIcmd\fR.

To do this, it searches an \fIauto-load path\fR, which is a list of

one or more directories.

The auto-load path is given by the global variable \fB$auto_path\fR

if it exists.

If there is no \fB$auto_path\fR 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

\fBtclIndex\fR that describes one

or more commands defined in that directory

and a script to evaluate to load each of the commands.

The \fBtclIndex\fR file should be generated with the

\fBauto_mkindex\fR command.

If \fIcmd\fR is found in an index file, then the appropriate

script is evaluated to create the command.

The \fBauto_load\fR command returns 1 if \fIcmd\fR was successfully

created.

The command returns 0 if there was no index entry for \fIcmd\fR

or if the script didn't actually define \fIcmd\fR (e.g. because

index information is out of date).

If an error occurs while processing the script, then that error

is returned.

\fBAuto_load\fR only reads the index information once and saves it

in the array \fBauto_index\fR;  future calls to \fBauto_load\fR

check for \fIcmd\fR in the array rather than re-reading the index

files.

The cached index information may be deleted with the command

\fBauto_reset\fR.

This will force the next \fBauto_load\fR command to reload the

index database from disk.

.TP

\fBauto_mkindex \fIdir pattern pattern ...\fR

Generates an index suitable for use by \fBauto_load\fR.

The command searches \fIdir\fR for all files whose names match

any of the \fIpattern\fR arguments

(matching is done with the \fBglob\fR 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 \fBtclIndex\fR in \fIdir\fR.

If no pattern is given a pattern of \fB*.tcl\fR will be assumed.

For example, the command

.RS

.CS

\fBauto_mkindex foo *.tcl\fR

.CE

.LP

will read all the \fB.tcl\fR files in subdirectory \fBfoo\fR

and generate a new index file \fBfoo/tclIndex\fR.

.PP

\fBAuto_mkindex\fR 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.

.PP

\fBAuto_mkindex_old\fR parses the Tcl scripts in a relatively

unsophisticated way:  if any line contains the word \fBproc\fR

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 \fBproc\fR) will not be indexed.

.RE

.TP

\fBauto_reset\fR

Destroys all the information cached by \fBauto_execok\fR and

\fBauto_load\fR.

This information will be re-read from disk the next time it is

needed.

\fBAuto_reset\fR 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.

.TP

\fBtcl_findLibrary \fIbasename version patch initScript enVarName varName\fR

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 \fIbasenameversion\fP

(e.g., tk8.0), but it might be "library" when in the build hierarchies.

The \fIinitScript\fR 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 \fIvarName\fP.

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 \fIenVarName\fP;

relative to the Tcl library directory;

relative to the executable file in the standard installation

bin or bin/\fIarch\fP directory;

relative to the executable file in the current build tree;

relative to the executable file in a parallel build tree.

.TP

\fBparray \fIarrayName\fR

Prints on standard output the names and values of all the elements

in the array \fIarrayName\fR.

\fBArrayName\fR must be an array accessible to the caller of \fBparray\fR.

It may be either local or global.

.TP

\fBtcl_endOfWord \fIstr start\fR

.VS

Returns the index of the first end-of-word location that occurs after

a starting index \fIstart\fR in the string \fIstr\fR.  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 \fBtcl_wordchars\fR and \fBtcl_nonwordchars\fR below

for more details on how Tcl determines which characters are word

characters.

.TP

\fBtcl_startOfNextWord \fIstr start\fR

Returns the index of the first start-of-word location that occurs

after a starting index \fIstart\fR in the string \fIstr\fR.  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.

.TP

\fBtcl_startOfPreviousWord \fIstr start\fR

Returns the index of the first start-of-word location that occurs

before a starting index \fIstart\fR in the string \fIstr\fR.  Returns

\-1 if there are no more start-of-word locations before the starting

point.

.TP

\fBtcl_wordBreakAfter \fIstr start\fR

Returns the index of the first word boundary after the starting index

\fIstart\fR in the string \fIstr\fR.  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.

.TP

\fBtcl_wordBreakBefore \fIstr start\fR

Returns the index of the first word boundary before the starting index

\fIstart\fR in the string \fIstr\fR.  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.

.VE

.SH "VARIABLES"

.PP

The following global variables are defined or used by the procedures in

the Tcl library:

.TP

\fBauto_execs\fR

Used by \fBauto_execok\fR to record information about whether

particular commands exist as executable files.

.TP

\fBauto_index\fR

Used by \fBauto_load\fR to save the index information read from

disk.

.TP

\fBauto_noexec\fR

If set to any value, then \fBunknown\fR will not attempt to auto-exec

any commands.

.TP

\fBauto_noload\fR

If set to any value, then \fBunknown\fR will not attempt to auto-load

any commands.

.TP

\fBauto_path\fR

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 variable,

the parent directory of $tcl_library,

the directories listed in the $tcl_pkgPath variable.

.TP

\fBenv(TCL_LIBRARY)\fR

If set, then it specifies the location of the directory containing

library scripts (the value of this variable will be

assigned to the \fBtcl_library\fR variable and therefore returned by

the command \fBinfo library\fR).  If this variable isn't set then

a default value is used.

.TP

\fBenv(TCLLIBPATH)\fR

If set, then it must contain a valid Tcl list giving directories to

search during auto-load operations.

This variable is only used when

initializing the \fBauto_path\fR variable.

.TP

\fBtcl_nonwordchars\fR

.VS

This variable contains a regular expression that is used by routines

like \fBtcl_endOfWord\fR 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.

.TP

\fBtcl_wordchars\fR

This variable contains a regular expression that is used by routines

like \fBtcl_endOfWord\fR 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.

.VE

.TP

\fBunknown_active\fR

This variable is set by \fBunknown\fR to indicate that it is active.

It is used to detect errors where \fBunknown\fR recurses on itself

infinitely.

The variable is unset before \fBunknown\fR returns.

.SH KEYWORDS

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