'\"
'\" Copyright (c) 2004-2010 Andreas Kupries <andreas_kupries@users.sourceforge.net>
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
.TH tm n 8.5 Tcl "Tcl Built-In Commands"
.\" The -*- nroff -*- definitions below are for supplemental macros used
.\" in Tcl/Tk manual entries.
.\"
.\" .AP type name in/out ?indent?
.\"	Start paragraph describing an argument to a library procedure.
.\"	type is type of argument (int, etc.), in/out is either "in", "out",
.\"	or "in/out" to describe whether procedure reads or modifies arg,
.\"	and indent is equivalent to second arg of .IP (shouldn't ever be
.\"	needed;  use .AS below instead)
.\"
.\" .AS ?type? ?name?
.\"	Give maximum sizes of arguments for setting tab stops.  Type and
.\"	name are examples of largest possible arguments that will be passed
.\"	to .AP later.  If args are omitted, default tab stops are used.
.\"
.\" .BS
.\"	Start box enclosure.  From here until next .BE, everything will be
.\"	enclosed in one large box.
.\"
.\" .BE
.\"	End of box enclosure.
.\"
.\" .CS
.\"	Begin code excerpt.
.\"
.\" .CE
.\"	End code excerpt.
.\"
.\" .VS ?version? ?br?
.\"	Begin vertical sidebar, for use in marking newly-changed parts
.\"	of man pages.  The first argument is ignored and used for recording
.\"	the version when the .VS was added, so that the sidebars can be
.\"	found and removed when they reach a certain age.  If another argument
.\"	is present, then a line break is forced before starting the sidebar.
.\"
.\" .VE
.\"	End of vertical sidebar.
.\"
.\" .DS
.\"	Begin an indented unfilled display.
.\"
.\" .DE
.\"	End of indented unfilled display.
.\"
.\" .SO ?manpage?
.\"	Start of list of standard options for a Tk widget. The manpage
.\"	argument defines where to look up the standard options; if
.\"	omitted, defaults to "options". The options follow on successive
.\"	lines, in three columns separated by tabs.
.\"
.\" .SE
.\"	End of list of standard options for a Tk widget.
.\"
.\" .OP cmdName dbName dbClass
.\"	Start of description of a specific option.  cmdName gives the
.\"	option's name as specified in the class command, dbName gives
.\"	the option's name in the option database, and dbClass gives
.\"	the option's class in the option database.
.\"
.\" .UL arg1 arg2
.\"	Print arg1 underlined, then print arg2 normally.
.\"
.\" .QW arg1 ?arg2?
.\"	Print arg1 in quotes, then arg2 normally (for trailing punctuation).
.\"
.\" .PQ arg1 ?arg2?
.\"	Print an open parenthesis, arg1 in quotes, then arg2 normally
.\"	(for trailing punctuation) and then a closing parenthesis.
.\"
.\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
.\"	# Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1 \\fI\\$2\\fP (\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1	\\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
.\"	# define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
.\"	# BS - start boxed text
.\"	# ^y = starting y location
.\"	# ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
.\"	# BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
.\"	# VS - start vertical sidebar
.\"	# ^Y = starting y location
.\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
.\"	# VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
.nf
.ti 0
.mk ^t
\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
.\"	# Special macro to handle page bottom:  finish off current
.\"	# box/sidebar if in box/sidebar mode, then invoked standard
.\"	# page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"	Draw three-sided box if this is the box's first page,
.\"	draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
.\}
.bp
'fi
.ev
.if \\n(^b \{\
.mk ^y
.nr ^b 2
.\}
.if \\n(^v \{\
.mk ^Y
.\}
..
.\"	# DS - begin display
.de DS
.RS
.nf
.sp
..
.\"	# DE - end display
.de DE
.fi
.RE
.sp
..
.\"	# SO - start of list of standard options
.de SO
'ie '\\$1'' .ds So \\fBoptions\\fR
'el .ds So \\fB\\$1\\fR
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
.\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\*(So manual entry for details on the standard options.
..
.\"	# OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
..
.\"	# CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
.\"	# CE - end code excerpt
.de CE
.fi
.RE
..
.\"	# UL - underline word
.de UL
\\$1\l'|0\(ul'\\$2
..
.\"	# QW - apply quotation marks to word
.de QW
.ie '\\*(lq'"' ``\\$1''\\$2
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\$2
..
.\"	# PQ - apply parens and quotation marks to word
.de PQ
.ie '\\*(lq'"' (``\\$1''\\$2)\\$3
.\"" fix emacs highlighting
.el (\\*(lq\\$1\\*(rq\\$2)\\$3
..
.\"	# QR - quoted range
.de QR
.ie '\\*(lq'"' ``\\$1''\\-``\\$2''\\$3
.\"" fix emacs highlighting
.el \\*(lq\\$1\\*(rq\\-\\*(lq\\$2\\*(rq\\$3
..
.\"	# MT - "empty" string
.de MT
.QW ""
..
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
tm \- Facilities for locating and loading of Tcl Modules
.SH SYNOPSIS
.nf
\fB::tcl::tm::path add \fR?\fIpath\fR...?
\fB::tcl::tm::path remove \fR?\fIpath\fR...?
\fB::tcl::tm::path list\fR
\fB::tcl::tm::roots \fR\fIpaths\fR
.fi
.BE
.SH DESCRIPTION
.PP
This document describes the facilities for locating and loading Tcl
Modules (see \fBMODULE DEFINITION\fR for the definition of a Tcl Module).
The following commands are supported:
.\" COMMAND: path
.\" METHOD: add
.TP
\fB::tcl::tm::path add \fR?\fIpath\fR...?
.
The paths are added at the head to the list of module paths, in order
of appearance. This means that the last argument ends up as the new
head of the list.
.RS
.PP
The command enforces the restriction that no path may be an ancestor
directory of any other path on the list. If any of the new paths
violates this restriction an error will be raised, before any of the
paths have been added. In other words, if only one path argument
violates the restriction then none will be added.
.PP
If a path is already present as is, no error will be raised and no
action will be taken.
.PP
Paths are searched later in the order of their appearance in the
list. As they are added to the front of the list they are searched in
reverse order of addition. In other words, the paths added last are
looked at first.
.RE
.\" METHOD: remove
.TP
\fB::tcl::tm::path remove \fR?\fIpath\fR...?
.
Removes the paths from the list of module paths. The command silently
ignores all paths which are not on the list.
.\" METHOD: list
.TP
\fB::tcl::tm::path list\fR
.
Returns a list containing all registered module paths, in the order
that they are searched for modules.
.\" COMMAND: roots
.TP
\fB::tcl::tm::roots \fR\fIpaths\fR
.
Similar to \fBpath add\fR, and layered on top of it. This command
takes a single argument containing a list of paths, extends each with
.QW "\fBtcl\fIX\fB/site-tcl\fR" ,
and
.QW "\fBtcl\fIX\fB/\fIX\fB.\fIy\fR" ,
for major version \fIX\fR of the
Tcl interpreter and minor version \fIy\fR less than or equal to the
minor version of the interpreter, and adds the resulting set of paths
to the list of paths to search.
.RS
.PP
This command is used internally by the system to set up the
system-specific default paths.
.PP
The command has been exposed to allow a build system to define
additional root paths beyond those described by this document.
.RE
.SH "MODULE DEFINITION"
.PP
A Tcl Module is a Tcl Package contained in a single file, and no other
files required by it. This file has to be \fBsource\fRable. In other
words, a Tcl Module is always imported via:
.PP
.CS
source module_file
.CE
.PP
The \fBload\fR command is not directly used. This restriction is not
an actual limitation, as some may believe.
Ever since 8.4 the Tcl \fBsource\fR command reads only until the first
^Z character. This allows us to combine an arbitrary Tcl script with
arbitrary binary data into one file, where the script processes the
attached data in any it chooses to fully import and activate the
package.
.PP
The name of a module file has to match the regular expression:
.PP
.CS
([_[:alpha:]][:_[:alnum:]]*)-([[:digit:]].*)\e.tm
.CE
.PP
The first capturing parentheses provides the name of the package, the
second clause its version. In addition to matching the pattern, the
extracted version number must not raise an error when used in the
command:
.PP
.CS
package vcompare $version 0
.CE
.SH "FINDING MODULES"
.PP
The directory tree for storing Tcl modules is separate from other
parts of the filesystem and independent of \fBauto_path\fR.
.PP
Tcl Modules are searched for in all directories listed in the result
of the command \fB::tcl::tm::path list\fR.
This is called the \fIModule path\fR. Neither the \fBauto_path\fR nor
the \fBtcl_pkgPath\fR variables are used.
All directories on the module path have to obey one restriction:
.RS
.PP
For any two directories, neither is an ancestor directory of the
other.
.RE
.PP
This is required to avoid ambiguities in package naming. If for
example the two directories
.QW "\fIfoo/\fR"
and
.QW "\fIfoo/cool\fR"
were on
the path a package named \fBcool::ice\fR could be found via the
names \fBcool::ice\fR or \fBice\fR, the latter potentially
obscuring a package named \fBice\fR, unqualified.
.PP
Before the search is started, the name of the requested package is
translated into a partial path, using the following algorithm:
.RS
.PP
All occurrences of
.QW "\fB::\fR"
in the package name are replaced by
the appropriate directory separator character for the platform we are
on. On Unix, for example, this is
.QW "\fB/\fR" .
.RE
.PP
Example:
.RS
.PP
The requested package is \fBencoding::base64\fR. The generated
partial path is
.QW "\fIencoding/base64\fR" .
.RE
.PP
After this translation the package is looked for in all module paths,
by combining them one-by-one, first to last with the partial path to
form a complete search pattern. Note that the search algorithm rejects
all files where the filename does not match the regular expression
given in the section \fBMODULE DEFINITION\fR. For the remaining
files \fIprovide scripts\fR are generated and added to the package
ifneeded database.
.PP
The algorithm falls back to the previous unknown handler when none of
the found module files satisfy the request. If the request was
satisfied the fall-back is ignored.
.PP
Note that packages in module form have \fIno\fR control over the
\fIindex\fR and \fIprovide script\fRs entered into the package
database for them.
For a module file \fBMF\fR the \fIindex script\fR is always:
.PP
.CS
package ifneeded \fBPNAME PVERSION\fR [list source \fBMF\fR]
.CE
.PP
and the \fIprovide script\fR embedded in the above is:
.PP
.CS
source \fBMF\fR
.CE
.PP
Both package name \fBPNAME\fR and package version \fBPVERSION\fR are
extracted from the filename \fBMF\fR according to the definition
below:
.PP
.CS
\fBMF\fR = /module_path/\fBPNAME\(fm\fR-\fBPVERSION\fR.tm
.CE
.PP
Where \fBPNAME\(fm\fR is the partial path of the module as defined in
section \fBFINDING MODULES\fR, and translated into \fBPNAME\fR by
changing all directory separators to
.QW "\fB::\fR" ,
and \fBmodule_path\fR is the path (from the list of paths to search)
that we found the module file under.
.PP
Note also that we are here creating a connection between package names
and paths. Tcl is case-sensitive when it comes to comparing package
names, but there are filesystems which are not, like NTFS. Luckily
these filesystems do store the case of the name, despite not using the
information when comparing.
.PP
Given the above we allow the names for packages in Tcl modules to have
mixed-case, but also require that there are no collisions when
comparing names in a case-insensitive manner. In other words, if a
package \fBFoo\fR is deployed in the form of a Tcl Module,
packages like \fBfoo\fR, \fBfOo\fR, etc. are not allowed
anymore.
.SH "DEFAULT PATHS"
.PP
The default list of paths on the module path is computed by a
\fBtclsh\fR as follows, where \fIX\fR is the major version of the Tcl
interpreter and \fIy\fR is less than or equal to the minor version of
the Tcl interpreter.
.PP
All the default paths are added to the module path, even those paths
which do not exist. Non-existent paths are filtered out during actual
searches. This enables a user to create one of the paths searched when
needed and all running applications will automatically pick up any
modules placed in them.
.PP
The paths are added in the order as they are listed below, and for
lists of paths defined by an environment variable in the order they
are found in the variable.
.SS "SYSTEM SPECIFIC PATHS"
.TP
\fBfile normalize [info library]/../tcl\fIX\fB/\fIX\fB.\fIy\fR
.
In other words, the interpreter will look into a directory specified
by its major version and whose minor versions are less than or equal
to the minor version of the interpreter.
.RS
.PP
For example for Tcl 8.4 the paths searched are:
.PP
.CS
\fB[info library]/../tcl8/8.4\fR
\fB[info library]/../tcl8/8.3\fR
\fB[info library]/../tcl8/8.2\fR
\fB[info library]/../tcl8/8.1\fR
\fB[info library]/../tcl8/8.0\fR
.CE
.PP
This definition assumes that a package defined for Tcl \fIX\fB.\fIy\fR
can also be used by all interpreters which have the same major number
\fIX\fR and a minor number greater than \fIy\fR.
.RE
.TP
\fBfile normalize EXEC/tcl\fIX\fB/\fIX\fB.\fIy\fR
.
Where \fBEXEC\fR is \fBfile normalize [info nameofexecutable]/../lib\fR
or \fBfile normalize [::tcl::pkgconfig get libdir,runtime]\fR
.RS
.PP
This sets of paths is handled equivalently to the set coming before,
except that it is anchored in \fBEXEC_PREFIX\fR.
For a build with \fBPREFIX\fR = \fBEXEC_PREFIX\fR the two sets are
identical.
.RE
.SS "SITE SPECIFIC PATHS"
.TP
\fBfile normalize [info library]/../tcl\fIX\fB/site-tcl\fR
.
Note that this is always a single entry because \fIX\fR is always a
specific value (the current major version of Tcl).
.SS "USER SPECIFIC PATHS"
.TP
\fB$::env(TCL\fIX\fB_\fIy\fB_TM_PATH)\fR
.
A list of paths, separated by either \fB:\fR (Unix) or \fB;\fR
(Windows). This is user and site specific as this environment variable
can be set not only by the user's profile, but by system configuration
scripts as well.
.TP
\fB$::env(TCL\fIX\fB.\fIy\fB_TM_PATH)\fR
.
Same meaning and content as the previous variable. However the use of
dot '.' to separate major and minor version number makes this name
less to non-portable and its use is discouraged. Support of this
variable has been kept only for backward compatibility with the
original specification, i.e. TIP 189.
.PP
These paths are seen and therefore shared by all Tcl shells in the
\fB$::env(PATH)\fR of the user.
.PP
Note that \fIX\fR and \fIy\fR follow the general rules set out
above. In other words, Tcl 9.1, for example, will look at these 4
environment variables:
.PP
.CS
\fB$::env(TCL9.1_TM_PATH)\fR  \fB$::env(TCL9_1_TM_PATH)\fR
\fB$::env(TCL9.0_TM_PATH)\fR  \fB$::env(TCL9_0_TM_PATH)\fR
.CE
.PP
Paths initialized from the environment variables undergo tilde
substitution (see \fBfilename\fR). Any path whose tilde substitution
fails because the user is unknown will be omitted from search paths.
.SH "SEE ALSO"
package(n), Tcl Improvement Proposal #189
.QW "\fITcl Modules\fR"
(online at https://core.tcl-lang.org/tips/doc/trunk/tip/189.md), Tcl Improvement Proposal #190
.QW "\fIImplementation Choices for Tcl Modules\fR"
(online at https://core.tcl-lang.org/tips/doc/trunk/tip/190.md)
.SH "KEYWORDS"
modules, package
.\" Local Variables:
.\" mode: nroff
.\" End:
