Check-in [f75ee55997]

{"tip": {
	"515":{"url":"./tip/515.md","created":"7-Sept-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"Pending","type":"Project","title":"# TIP 515: Level Value Reform","author":["Jan Nijtmans <[email protected]>"],"is-jest":false},
	"514":{"url":"./tip/514.md","keywords":"Tcl","created":"20-Aug-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"Pending","type":"Project","title":"# TIP 514: Platform differences in handling int/wide","author":["Jan Nijtmans <[email protected]>"],"is-jest":false},
	"513":{"url":"./tip/513.md","keywords":"Tcl,data structure","created":"02-Aug-2017","post-history":"","state":"Draft","tcl-version":"8.7","vote":"Pending","type":"Project","title":"# TIP 513: Better support for 'agendas' as arrays, dictionaries or lists","author":["Florian Murr <[email protected]>"],"is-jest":false},
	"512":{"url":"./tip/512.md","keywords":"Tcl","created":"25-June-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"Pending","type":"Project","title":"# TIP 512: No stub for Tcl_SetExitProc()","author":["Jan Nijtmans <[email protected]>"],"is-jest":false},
	"511":{"url":"./tip/511.md","keywords":"Tcl,threads","created":"14-June-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"Pending","type":"Project","title":"# TIP 511: Implement Tcl_AsyncMarkFromSignal()","author":["Christian Werner <[email protected]>"],"is-jest":false},
	"510":{"url":"./tip/510.md","keywords":"Tk","created":"5-Jun-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"","type":"Project","title":"# TIP 510: Add Rbc to Tk","author":["René Zaumseil <[email protected]>"],"is-jest":false},
	"509":{"url":"./tip/509.md","keywords":"Tcl,threads","created":"24-May-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"","type":"Project","title":"# TIP 509: Implement reentrant mutexes on all platforms","author":["Frédéric Bonnet <[email protected]>"],"is-jest":false},
	"508":{"url":"./tip/508.md","keywords":"Tcl,array","created":"13-May-2018","post-history":"","state":"Draft","tcl-version":"8.7","vote":"","type":"Project","title":"# TIP 508: New subcommand [array default]","author":["Frédéric Bonnet <[email protected]>"],"is-jest":false},

	"5":{"url":"./tip/5.md","created":"17-Oct-2000","post-history":"","state":"Final","vote":"Done","tcl-version":"8.4","type":"Project","title":"# TIP 5: Make TkClassProcs and TkSetClassProcs Public and Extensible","author":["Eric Melski <[email protected]>"],"is-jest":false},
	"4":{"url":"./tip/4.md","created":"26-Oct-2000","post-history":"","state":"Draft","vote":"Pending","type":"Informative","title":"# TIP 4: Tcl Release and Distribution Philosophy","discussions-to":"news comp.lang.tcl","author":["Brent Welch <[email protected]>","Donal K. Fellows <[email protected]>","Larry W. Virden <[email protected]>","Larry W. Virden <[email protected]>"],"is-jest":false},
	"3":{"url":"./tip/3.md","created":"14-Sep-2000","post-history":"","state":"Accepted","vote":"Done","type":"Process","title":"# TIP 3: TIP Format","author":["Andreas Kupries <[email protected]>","Donal K. Fellows <[email protected]>"],"is-jest":false},
	"2":{"url":"./tip/2.md","created":"12-Sep-2000","post-history":"","state":"Draft","vote":"Pending","type":"Process","title":"# TIP 2: TIP Guidelines","author":["Andreas Kupries <[email protected]>","Donal K. Fellows <[email protected]>","Don Porter <[email protected]>","Mo DeJong <[email protected]>","Larry W. Virden <[email protected]>","Kevin Kenny <[email protected]>"],"is-jest":false},
	"1":{"url":"./tip/1.md","created":"14-Sep-2000","post-history":"","state":"Active","vote":"No voting","type":"Informational","title":"# TIP 1: TIP Index","author":["TIP Editor <[email protected]>"],"is-jest":false},
	"0":{"url":"./tip/0.md","created":"11-Dec-2000","post-history":"","state":"Final","vote":"Done","type":"Process","title":"# TIP 0: Tcl Core Team Basic Rules","author":["John Ousterhout <[email protected]>"],"is-jest":false},
	"@min": 0,
	"@max": 515
}, "@timestamp": 1536313728}

<th>#</th>
<th>Type</th>
<th>Tcl Version</th>
<th>Status</th>
<th>Title</th>
</tr></thead><tbody>

<tr class='project projectdraft projectdraft87 project87'>
<td valign='top'><a href='./tip/515.md'>515</a></td>
<td valign='top'>Project</td>
<td valign='top'>8.7</td>
<td valign='top'>Draft</td>
<td valign='top'># TIP 515: Level Value Reform</td>
</tr>
<tr class='project projectdraft projectdraft87 project87'>
<td valign='top'><a href='./tip/514.md'>514</a></td>
<td valign='top'>Project</td>
<td valign='top'>8.7</td>
<td valign='top'>Draft</td>
<td valign='top'># TIP 514: Platform differences in handling int/wide</td>
</tr>

 * If you still really want to protect some command argument from overflowing, Use Tcl\_GetWideIntFromObj() in this command, and use "string is wide" to check for proper range.
   But - still better - is use Tcl\_GetWideIntFromObj(), with falling back to Tcl\_GetBignumFromObj() if the range requires it.
   That's what Tcl itself is doing almost everywhere to prevent under/overflow errors.

# Implementation

Currently, the proposed implementation is available in the [tip-514 branch]
(https://core.tcl.tk/tcl/timeline?r=tip-514).

# Copyright

This document has been placed in the public domain.

# TIP 515: Level Value Reform
	Author:         Jan Nijtmans <[email protected]>
	State:          Draft
	Type:           Project
	Vote:           Pending
	Created:        7-Sept-2018
	Post-History:   
	Tcl-Version:	8.7
-----

# Abstract

Proposes reformed handling of Tcl level values. This TIP is inspired by TIP #502, which handles "index" values, realizing that "level" values have
kind of the same problems as described there.

# Background

Many Tcl programmers may be surprised by these results

	% apply {{} {uplevel -4294967294 {puts OK}}}
	bad level "-4294967294"  (OK, this is expected ....)
	% apply {{} {uplevel -4294967295 {puts OK}}}
	OK
	% apply {{} {uplevel -4294967296 {puts OK}}}
	invalid command name "-4294967296"

I would expect the same "bad level" error in all 3 cases.
Or:

	% proc todo arg {puts $arg}
	% apply {{} {uplevel todo OK}}
	OK
	% proc 2do arg {puts $arg}
	% apply {{} {uplevel 2do OK}}
	bad level "2do"

Why can't we call a command "2do"? The parser appears to be confused because the command name starts with a digit.

# Proposal

Revise the parsing of values used as level values to accept all
integer representations acceptable to **expr**, optionally
preceded by "#".

Although this suggests an unlimited range of valid levels,
in practice all out-of-range levels (either a negative number,
either a number higher than the actual available number of levels) ,
will result in a "bad level" error.

# Compatibility

Examples like the ones in the Background above will incompatibly
change from one outcome to a different outcome.
This is a true incompatibility, but it is difficult to believe anyone
actually desires the outlier behaviors illustrated above, much less has
code that relies on them.

New behavior, one that succeeded in Tcl 8.6 but should actually fail:

	% apply {{} {uplevel -4294967295 {puts OK}}}
	bad level "-4294967295"

Another example, of a situation that failed in Tcl 8.6 but should succeed:

    $ proc 2do arg {puts $arg}
	% apply {{} {uplevel 2do OK}}
	OK

# Implementation

Currently, the proposed implementation is available in the [tip-515 branch]
(https://core.tcl.tk/tcl/timeline?r=tip-515).

# Copyright

This document has been placed in the public domain.