Author:        Jan Nijtmans <[email protected]>
    State:         Final
    Type:          Project
    Vote:          Done
    Created:       24-05-2022
    Tcl-Version:   9.1
    Keywords:      Tcl
    Tcl-Branch:    tip-626
    Vote-Summary:  Accepted 4/0/1
    Votes-For:     AK, HO, JN, SL
    Votes-Against: none
    Votes-Present: AN

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Abstract

This TIP proposes to change Tcl internally, to use Tcl_CreateObjCommand2() and friends (TIP #627 and #630), and to change all internal handling, allowing > 2^31 command line elements. This doesn't change any API (since the API is already available), but it has some consequences.

Rationale

The new functions in TIP #627 and #630 allow any list to be converted to a command, without worrying about the length of the list. It completes the conversion of Tcl and Tk, using Tcl_Size internally in stead of int, everywhere.

Example:

% set s [string cat {*}[lrepeat 0x100000000 x]]; string length $s            

4294967296

This doesn't mean that all commands using such large arguments actually run: they might panic because they use more memory than available in the system. TIP #721 is meant to remedy this, by turning the panic into a run-time error, but that's out-of-scope for this TIP.

Specification

Starting with Tcl/Tk 9.1, the following 8 functions (and 3 for Itcl) are capable of using either Tcl_Size type arguments or int type arguments, if your compiler is c11-capable:

• Tcl_CreateObjCommand
• Tcl_CreateTrace
• Tcl_CreateObjTrace
• Tcl_NRCallObjProc
• Tcl_NRCreateCommand
• Tcl_MethodIsType
• Tcl_NewInstanceMethod
• Tcl_NewMethod
• Itcl_RegisterC (Itcl)
• Itcl_RegisterObjC (Itcl)
• Itcl_FindC (Itcl)

If your compiler is not c11-capable, the *2 versions of TIP #627 and #630 functions can be used directly, enabling the increased number of arguments. With c11-compatibility, you can simply leave out the 2 in the function name.

It also means that - due to the internal changes - some extensions which depend on the internal behavior won't work any more as-is. Especially nsf will need to be modified.

For extensions which only depend on the public API, everything works as before.

Implementation

See branch tip-626

The idea (and implementation) of using the c11-capability, is stolen from the c11-generic-oo-api branch (thanks, @dkf!).

The Itcl part of this TIP is not implemented yet, but that will follow soon after this TIP is accepted.

Copyright

This document has been placed in the public domain.