The Tcl API (also called' Tcl library' or' Tcl C interface') is a huge set of C functions which can be used to create binary extensions to the Tcl language. The functions cover the whole range of Tcl and are, if used right, platform-independent.
A complete list of the functions and their documentation can be found here:
The new functions that were added in Tcl 8.5 are listed in: Tcl/Tk 8.5: New public C routines
Many of the API functions make use of the Tcl_Obj structure that was introduced in Tcl 8.0. For more general information of Tcl_Obj see:
The file tcl.h should be considered a public declaration of the Tcl C functions, defines/macros, and structures which a developer can safely depend on. (Some extensions also use things from tclInt.h, but the price for that is that they require more maintenance in order to keep working. Stick with tcl.h as long as possible.) Most of the actual function declarations are found in the tclDecls.h file; this has to do with the Stubs mechanism.
LV When I look in tcl.h, I see only 3 functions listed, along with 2 tcl related #include lines - tclDecls.h and tclPlatDecls.h. Is it correct to assume that the nearly 600 functions declared as EXTERN in the two additional files (in Tcl 8.5) are all considered a part of the public API for Tcl?
The following list may not be comprehensive, but the Tcl C API functions include:
[A list by topic (where related functions are collected together) should be more useful, as the HTML docs already provide this kind of alphabetic list.] [Feel free to organize data on the wiki in the way that helps you most - or seems to be most helpful.]