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

NAME
       load - Load machine code and initialize new commands.

SYNOPSIS
       llooaadd fileName
       llooaadd fileName packageName
       llooaadd fileName packageName interp



DESCRIPTION
       This  command  loads  binary  code  from  a file into the application's
       address space and calls an initialization procedure in the  package  to
       incorporate  it  into an interpreter.  fileName is the name of the file
       containing the code;  its exact form varies from system to  system  but
       on  most  systems  it  is  a  shared  library, such as a ..ssoo file under
       Solaris or a DLL under Windows.  packageName is the name of  the  pack-
       age,  and  is  used to compute the name of an initialization procedure.
       interp is the path name of the interpreter into which to load the pack-
       age (see the iinntteerrpp manual entry for details); if interp is omitted, it
       defaults to the interpreter in which the llooaadd command was invoked.

       Once the file has been loaded into the application's address space, one
       of two initialization procedures will be invoked in the new code.  Typ-
       ically the initialization procedure will add  new  commands  to  a  Tcl
       interpreter.  The name of the initialization procedure is determined by
       packageName and whether or not the target interpreter is  a  safe  one.
       For  normal  interpreters the name of the initialization procedure will
       have the form pkgIInniitt, where pkg is the  same  as  packageName  except
       that  the first letter is converted to upper case and all other letters
       are converted to lower case.  For example, if  packageName  is  ffoooo  or
       FFOOoo, the initialization procedure's name will be FFooooIInniitt.

       If  the  target interpreter is a safe interpreter, then the name of the
       initialization procedure will be pkgSSaaffeeIInniitt instead of pkgIInniitt.  The
       pkgSSaaffeeIInniitt  function should be written carefully, so that it initial-
       izes the safe interpreter only with partial functionality  provided  by
       the  package  that is safe for use by untrusted code. For more informa-
       tion on Safe-Tcl, see the ssaaffee manual entry.

       The initialization procedure must match the following prototype:
              typedef int TclPackageInitProc(TclInterp *interp);
       The interp argument identifies the interpreter in which the package  is
       to  be  loaded.   The  initialization  procedure  must return TTCCLLOOKK or
       TTCCLLEERRRROORR to indicate whether or not it completed successfully;  in the
       event of an error it should set the interpreter's result to point to an
       error message.  The result of the  llooaadd  command  will  be  the  result
       returned by the initialization procedure.

       The  actual  loading of a file will only be done once for each fileName
       in an application.  If a given fileName is loaded into multiple  inter-
       preters,  then  the first llooaadd will load the code and call the initial-
       ization procedure;  subsequent llooaadds will call the initialization  pro-
       cedure without loading the code again.  It is not possible to unload or
       reload a package.

       The llooaadd command also supports packages that are statically linked with
       the  application, if those packages have been registered by calling the
       TTccllSSttaattiiccPPaacckkaaggee procedure.  If fileName  is  an  empty  string,  then
       packageName must be specified.

       If packageName is omitted or specified as an empty string, Tcl tries to
       guess the name of the package.  This may be done differently on differ-
       ent  platforms.   The  default  guess, which is used on most UNIX plat-
       forms, is to take the last element of fileName,  strip  off  the  first
       three  characters if they are lliibb, and use any following alphabetic and |
       underline characters as the module name.  For example, the command llooaadd
       lliibbxxyyzz44..22..ssoo  uses the module name xxyyzz and the command llooaadd bbiinn//llaasstt..ssoo
       {{}} uses the module name llaasstt.

       If fileName is an empty string, then  packageName  must  be  specified. |
       The  llooaadd  command  first searches for a statically loaded package (one |
       that has been registered by calling the TTccllSSttaattiiccPPaacckkaaggee procedure) by |
       that  name;  if  one is found, it is used.  Otherwise, the llooaadd command |
       searches for a dynamically loaded package by that name, and uses it  if |
       it  is found.  If several different files have been llooaadded with differ- |
       ent versions of the package, Tcl picks the file that was loaded  first.


PPOORRTTAABBIILLIITTYY IISSSSUUEESS
       WWiinnddoowwss
              When  a  load  fails  with "library not found" error, it is also
              possible that a dependent library was not  found.   To  see  the
              dependent  libraries,  type  ``dumpbin -imports '' in a
              DOS console to see what the library must import.  When loading a
              DLL  in  the  current directory, Windows will ignore ``./'' as a
              path specifier and use  a  search  heuristic  to  find  the  DLL
              instead.  To avoid this, load the DLL with
                  load [file join [pwd] mylib.DLL]


BUGS
       If  the  same  file is llooaadded by different fileNames, it will be loaded
       into the process's address space multiple times.  The behavior of  this
       varies  from  system  to  system (some systems may detect the redundant
       loads, others may not).


SEE ALSO
       info sharedlibextension, TclStaticPackage(3), safe(n)


KKEEYYWWOORRDDSS
       binary code, loading, safe interpreter, shared library



Tcl                                   7.5                              load(n)