Страницы справочника OS X

Эта страница руководства для  версии 10.9 Mac OS X

Читать страницы руководства

pkg_mkIndex(n)                              Tcl Built-In Commands                             pkg_mkIndex(n)



____________________________________________________________________________________________________________

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  exe-cuted. executed.
       cuted.  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  argu-ment; argument;
              ment;  for example, if the file is test.so it must be possible to load this file with the com-mand command
              mand 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  inter-preter interpreter
              preter  and  seeing what packages and new commands appear (this is why it is essential 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 vari-able. variable.
              able.  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 second 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 interpreter 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  con-trol. control.
       trol.

HOW IT WORKS
       Pkg_mkIndex  depends  on  the  package  unknown  command, the package ifneeded command, and the auto-loader. autoloader.
       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 pkgIndex.tcl files in the
       auto_path.  The pkgIndex.tcl files contain package ifneeded commands for each version of each  avail-able available
       able  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 pos-sible possible
       sible 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(n)

KEYWORDS
       auto-load, index, package, version



Tcl                                                  8.3                                      pkg_mkIndex(n)