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


       load - Load machine code and initialize new commands.

       load fileName
       load fileName packageName
       load fileName packageName interp

       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.   file-
       Name  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 .so file under Solaris  or	a
       DLL  under  Windows.   packageName  is the name of the package, and is used to compute the
       name of an initialization procedure.  interp is the path  name  of  the	interpreter  into
       which to load the package (see the interp manual entry for details); if interp is omitted,
       it defaults to the interpreter in which the load command was invoked.

       Once the file has been loaded into the application's address space, one of two initializa-
       tion  procedures  will be invoked in the new code.  Typically 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	pkg_Init,
       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
       foo or FOo, the initialization procedure's name will be Foo_Init.

       If  the target interpreter is a safe interpreter, then the name of the initialization pro-
       cedure will be pkg_SafeInit instead of pkg_Init.   The  pkg_SafeInit  function  should  be
       written carefully, so that it initializes the safe interpreter only with partial function-
       ality provided by the package that is safe for use by untrusted code. For more information
       on Safe-Tcl, see the safe manual entry.

       The initialization procedure must match the following prototype:
	      typedef int Tcl_PackageInitProc(Tcl_Interp *interp);
       The  interp argument identifies the interpreter in which the package is to be loaded.  The
       initialization procedure must return TCL_OK or TCL_ERROR 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 load 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 interpreters, then the first  load  will  load
       the  code  and call the initialization procedure;  subsequent loads will call the initial-
       ization procedure without loading the code again.  It is not possible to unload or  reload
       a package.

       The  load  command also supports packages that are statically linked with the application,
       if those packages have been registered by calling  the  Tcl_StaticPackage  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 different	platforms.   The  default  guess,
       which  is  used on most UNIX platforms, is to take the last element of fileName, strip off
       the first three characters if they are lib, and use any following alphabetic and underline |
       characters as the module name.  For example, the command load libxyz4.2.so uses the module
       name xyz and the command load bin/last.so {} uses the module name last.

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

	      When a load fails with "library not found" error, it is also possible that a depen-
	      dent library was not  found.   To  see  the  dependent  libraries,  type	``dumpbin
	      -imports	<dllname>''  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 speci-
	      fier  and  use a search heuristic to find the DLL instead.  To avoid this, load the
	      DLL with
		  load [file join [pwd] mylib.DLL]

       If the same file is loaded 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).

       info sharedlibextension, Tcl_StaticPackage(3), safe(n)

       binary code, loading, safe interpreter, shared library

Tcl					       7.5					  load(n)
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