1Tcl_InitStubs(3) Tcl Library Procedures Tcl_InitStubs(3)
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8 Tcl_InitStubs - initialize the Tcl stubs mechanism
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11 #include <tcl.h>
12 const char *
14 Tcl_InitStubs(interp, version, exact)
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17 Tcl_Interp *interp (in) Tcl interpreter handle.
18 const char *version (in) A version string consisting of one or
20 more decimal numbers separated by
21 dots.
22 int exact (in) Non-zero means that only the particu‐
24 lar version specified by version is
25 acceptable. Zero means that versions
26 newer than version are also acceptable
27 as long as they have the same major
28 version number as version.
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32 The Tcl stubs mechanism defines a way to dynamically bind extensions to
33 a particular Tcl implementation at run time. This provides two signif‐
34 icant benefits to Tcl users:
35 1) Extensions that use the stubs mechanism can be loaded into multi‐
37 ple versions of Tcl without being recompiled or relinked.
38 2) Extensions that use the stubs mechanism can be dynamically loaded
40 into statically-linked Tcl applications.
41 The stubs mechanism accomplishes this by exporting function tables that
43 define an interface to the Tcl API. The extension then accesses the
44 Tcl API through offsets into the function table, so there are no direct
45 references to any of the Tcl library's symbols. This redirection is
46 transparent to the extension, so an extension writer can continue to
47 use all public Tcl functions as documented.
48 The stubs mechanism requires no changes to applications incorporating
50 Tcl interpreters. Only developers creating C-based Tcl extensions need
51 to take steps to use the stubs mechanism with their extensions.
52 Enabling the stubs mechanism for an extension requires the following
54 steps:
55 1) Call Tcl_InitStubs in the extension before calling any other Tcl
57 functions.
58 2) Define the USE_TCL_STUBS symbol. Typically, you would include the
60 -DUSE_TCL_STUBS flag when compiling the extension.
61 3) Link the extension with the Tcl stubs library instead of the stan‐
63 dard Tcl library. For example, to use the Tcl 8.6 ABI on Unix
64 platforms, the library name is libtclstub8.6.a; on Windows plat‐
65 forms, the library name is tclstub86.lib.
66 If the extension also requires the Tk API, it must also call Tk_Init‐
68 Stubs to initialize the Tk stubs interface and link with the Tk stubs
69 libraries. See the Tk_InitStubs page for more information.
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72 Tcl_InitStubs attempts to initialize the stub table pointers and ensure
73 that the correct version of Tcl is loaded. In addition to an inter‐
74 preter handle, it accepts as arguments a version number and a Boolean
75 flag indicating whether the extension requires an exact version match
76 or not. If exact is 0, then the extension is indicating that newer
77 versions of Tcl are acceptable as long as they have the same major ver‐
78 sion number as version; non-zero means that only the specified version
79 is acceptable. Tcl_InitStubs returns a string containing the actual
80 version of Tcl satisfying the request, or NULL if the Tcl version is
81 not acceptable, does not support stubs, or any other error condition
82 occurred.
83
85 Tk_InitStubs
86
88 stubs
89Tcl 8.1 Tcl_InitStubs(3)