Mark Summerfield <[email protected]> posted:

I want these functions:

proc diff {old new} -> # diff data "ddata"
proc patch {old ddata} -> # new

where old and new are strings.

I thought the Tcllib's rcs module could do this but I can't figure it out.

Is this possible using the rcs module or using the struct::list module's
LCS functions?

The patch functionality (but not the diff) is provided by the textutil package, if I understand it correctly.

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Mark Summerfield <[email protected]> wrote:

I want these functions:

proc diff {old new} -> # diff data "ddata"
proc patch {old ddata} -> # new

where old and new are strings.

I thought the Tcllib's rcs module could do this but I can't figure it out.

Is this possible using the rcs module or using the struct::list module's
LCS functions?

The core of the diff algorithm is LCS. You want the LCS functions from struct::list.

But, you don't get a "diff" from the LCS procs, you get the LCS data,
you then have to convert that into a "diff" format of your choice.

You likely want to look at the various "diff in tcl" pages on the wiki.
A starting point: https://wiki.tcl-lang.org/page/diff+in+Tcl

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If you don't mind binary extensions, you may want to look at the
DiffUtil package - https://github.com/pspjuth/DiffUtilTcl

% package require DiffUtil
0.4.1
% DiffUtil::diffStrings abcdefgh abXdefgY
ab ab c X defg defg h Y {} {}

I don't think it's been ported to Tcl 9 though.

/Ashok

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Am 18.06.2025 um 13:19 schrieb Ashok:

If you don't mind binary extensions, you may want to look at the DiffUtil package - https://github.com/pspjuth/DiffUtilTcl

% package require DiffUtil
0.4.1
% DiffUtil::diffStrings abcdefgh abXdefgY
ab ab c X defg defg h Y {} {}

I don't think it's been ported to Tcl 9 though.

/Ashok

BAWT contains a Tcl9 ready version of DiffUtil (0.4.3), see https://wiki.tcl-lang.org/page/Porting+extensions+to+Tcl+9

Paul

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