Tcl8.6/Tk8.6 Documentation > Tcl C API, version 8.6.8 > InitStubs
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- Tcl_InitStubs — initialize the Tcl stubs mechanism
- #include <tcl.h>
- const char *
- Tcl_InitStubs(interp, version, exact)
- const char *
- SEE ALSO
const char *
Tcl_InitStubs(interp, version, exact)
- Tcl_Interp *interp (in)
- Tcl interpreter handle.
- const char *version (in)
- A version string consisting of one or more decimal numbers separated by dots.
- int exact (in)
- Non-zero means that only the particular version specified by version is acceptable. Zero means that versions newer than version are also acceptable as long as they have the same major version number as version.
- Extensions that use the stubs mechanism can be loaded into multiple versions of Tcl without being recompiled or relinked.
- Extensions that use the stubs mechanism can be dynamically loaded into statically-linked Tcl applications.
The stubs mechanism accomplishes this by exporting function tables that define an interface to the Tcl API. The extension then accesses the Tcl API through offsets into the function table, so there are no direct references to any of the Tcl library's symbols. This redirection is transparent to the extension, so an extension writer can continue to use all public Tcl functions as documented.
The stubs mechanism requires no changes to applications incorporating Tcl interpreters. Only developers creating C-based Tcl extensions need to take steps to use the stubs mechanism with their extensions.
Enabling the stubs mechanism for an extension requires the following steps:
- Call Tcl_InitStubs in the extension before calling any other Tcl functions.
- Define the USE_TCL_STUBS symbol. Typically, you would include the -DUSE_TCL_STUBS flag when compiling the extension.
- Link the extension with the Tcl stubs library instead of the standard Tcl library. For example, to use the Tcl 8.6 ABI on Unix platforms, the library name is libtclstub8.6.a; on Windows platforms, the library name is tclstub86.lib.