pkg_mkIndex(3tcl)                                              Tcl Built-In Commands                                             pkg_mkIndex(3tcl)

__________________________________________________________________________________________________________________________________________________

NAME

       pkg_mkIndex - Build an index for automatic loading of packages

SYNOPSIS

       pkg_mkIndex ?-direct?  ?-lazy?  ?-load pkgPat? ?-verbose? dir ?pattern pattern ...?
_________________________________________________________________

DESCRIPTION

       Pkg_mkIndex  is  a  utility procedure that is part of the standard Tcl library.  It is used to create index files that allow packages to be
       loaded automatically when package require commands are executed.  To use pkg_mkIndex, follow these steps:

       [1]    Create the package(s).  Each package may consist of one or more Tcl script files or binary files.  Binary files must be suitable for
              loading  with  the  load  command with a single argument;  for example, if the file is test.so it must be possible to load this file
              with the command load test.so.  Each script file must contain a package provide command to declare the package and  version  number,
              and each binary file must contain a call to Tcl_PkgProvide.

       [2]    Create  the index by invoking pkg_mkIndex.  The dir argument gives the name of a directory and each pattern argument is a glob-style
              pattern that selects script or binary files in dir.  The default pattern is *.tcl and *.[info sharedlibextension].

              Pkg_mkIndex will create a file pkgIndex.tcl in dir with package information about all the files given by the pattern arguments.   It
              does  this  by loading each file into a slave interpreter and seeing what packages and new commands appear (this is why it is essen-
              tial to have package provide commands or Tcl_PkgProvide calls in the files, as described above).  If you have a package split  among
              scripts and binary files, or if you have dependencies among files, you may have to use the -load option or adjust the order in which
              pkg_mkIndex processes the files.  See COMPLEX CASES below.

       [3]    Install the package as a subdirectory of one of the directories given by the tcl_pkgPath variable.  If  $tcl_pkgPath  contains  more
              than one directory, machine-dependent packages (e.g., those that contain binary shared libraries) should normally be installed under
              the first directory and machine-independent packages (e.g., those that contain only Tcl scripts) should be installed under the  sec-
              ond  directory.  The subdirectory should include the package's script and/or binary files as well as the pkgIndex.tcl file.  As long
              as the package is installed as a subdirectory of a directory in $tcl_pkgPath it will automatically be found during  package  require
              commands.

              If  you install the package anywhere else, then you must ensure that the directory containing the package is in the auto_path global
              variable or an immediate subdirectory of one of the directories in auto_path.  Auto_path contains a list  of  directories  that  are
              searched by both the auto-loader and the package loader; by default it includes $tcl_pkgPath.  The package loader also checks all of
              the subdirectories of the directories in auto_path.  You can add a directory to auto_path explicitly in your application, or you can
              add  the directory to your TCLLIBPATH environment variable:  if this environment variable is present, Tcl initializes auto_path from
              it during application startup.

       [4]    Once the above steps have been taken, all you need to do to use a package is to invoke package require.  For  example,  if  versions
              2.1, 2.3, and 3.1 of package Test have been indexed by pkg_mkIndex, the command package require Test will make version 3.1 available
              and the command package require -exact Test 2.1 will make version 2.1 available.  There may be many versions of  a  package  in  the
              various  index  files  in auto_path, but only one will actually be loaded in a given interpreter, based on the first call to package
              require.  Different versions of a package may be loaded in different interpreters.

OPTIONS

       The optional switches are:

       -direct        The generated index will implement direct loading of the package upon package require.  This is the default.

       -lazy          The generated index will manage to delay loading the package until the use of one of the commands provided by  the  package,
                      instead  of  loading  it immediately upon package require.  This is not compatible with the use of auto_reset, and therefore
                      its use is discouraged.

       -load pkgPat   The index process will pre-load any packages that exist in the current interpreter and match pkgPat into  the  slave  inter-
                      preter  used  to  generate the index.  The pattern match uses string match rules, but without making case distinctions.  See
                      COMPLEX CASES below.

       -verbose       Generate output during the indexing process.  Output is via the tclLog procedure, which by default prints to stderr.

       --             End of the flags, in case dir begins with a dash.

PACKAGES AND THE AUTO-LOADER
       The package management facilities overlap somewhat with the auto-loader, in that both arrange for files to be loaded  on-demand.   However,
       package  management is a higher-level mechanism that uses the auto-loader for the last step in the loading process.  It is generally better
       to index a package with pkg_mkIndex rather than auto_mkindex because the package mechanism provides version control:  several versions of a
       package  can  be made available in the index files, with different applications using different versions based on package require commands.
       In contrast, auto_mkindex does not understand versions so it can only handle a single version of each package.  It is probably not  a  good
       idea  to  index  a given package with both pkg_mkIndex and auto_mkindex.  If you use pkg_mkIndex to index a package, its commands cannot be
       invoked until package require has been used to select a version;  in contrast, packages indexed with auto_mkindex can be  used  immediately
       since there is no version control.

HOW IT WORKS

       Pkg_mkIndex  depends  on  the package unknown command, the package ifneeded command, and the auto-loader.  The first time a package require
       command is invoked, the package unknown script is invoked.  This is set by Tcl initialization to a script that evaluates all of the  pkgIn-
       dex.tcl  files  in  the  auto_path.   The  pkgIndex.tcl files contain package ifneeded commands for each version of each available package;
       these commands invoke package provide commands to announce the availability of the package, and they setup auto-loader information to  load
       the  files  of the package.  If the -lazy flag was provided when the pkgIndex.tcl was generated, a given file of a given version of a given
       package is not actually loaded until the first time one of its commands is invoked.  Thus, after invoking package require you may  not  see
       the package's commands in the interpreter, but you will be able to invoke the commands and they will be auto-loaded.

DIRECT LOADING

       Some  packages,  for instance packages which use namespaces and export commands or those which require special initialization, might select
       that their package files be loaded immediately upon package require instead of delaying the actual loading to the first use of one  of  the
       package's command. This is the default mode when generating the package index.  It can be overridden by specifying the -lazy argument.

COMPLEX CASES

       Most  complex cases of dependencies among scripts and binary files, and packages being split among scripts and binary files are handled OK.
       However, you may have to adjust the order in which files are processed by pkg_mkIndex.  These issues are described in detail below.

       If each script or file contains one package, and packages are only contained in one file, then things are easy.   You  simply  specify  all
       files to be indexed in any order with some glob patterns.

       In  general,  it  is OK for scripts to have dependencies on other packages.  If scripts contain package require commands, these are stubbed
       out in the interpreter used to process the scripts, so these do not cause problems.  If scripts call into other packages  in  global  code,
       these  calls  are  handled  by a stub unknown command.  However, if scripts make variable references to other package's variables in global
       code, these will cause errors.  That is also bad coding style.

       If binary files have dependencies on other packages, things can become tricky because it is not possible to stub out C-level APIs  such  as
       Tcl_PkgRequire  API  when  loading  a  binary  file.   For  example, suppose the BLT package requires Tk, and expresses this with a call to
       Tcl_PkgRequire in its Blt_Init routine.  To support this, you must run pkg_mkIndex in an interpreter that has Tk loaded.  You  can  achieve
       this  with  the  -load  pkgPat option.  If you specify this option, pkg_mkIndex will load any packages listed by info loaded and that match
       pkgPat into the interpreter used to process files.  In most cases this will satisfy the Tcl_PkgRequire calls made by binary files.

       If you are indexing two binary files and one depends on the other, you should specify the one that has dependencies last.  This way the one
       without  dependencies  will  get  loaded and indexed, and then the package it provides will be available when the second file is processed.
       You may also need to load the first package into the temporary interpreter used to create the index by using the -load flag;  it  will  not
       hurt to specify package patterns that are not yet loaded.

       If you have a package that is split across scripts and a binary file, then you should avoid the -load flag. The problem is that if you load
       a package before computing the index it masks any other files that provide part of the same package.  If you must use -load, then you  must
       specify the scripts first; otherwise the package loaded from the binary file may mask the package defined by the scripts.

SEE ALSO

       package(3tcl)

KEYWORDS

       auto-load, index, package, version

Tcl                                                                     8.3                                                      pkg_mkIndex(3tcl)