[Tcl-bugs] [ tcl-Bugs-1902890 ] compiled regexp behaves differently

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Bugs item #1902890, was opened at 2008-02-27 08:20
Message generated for change (Comment added) made by msofer
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Category: 47. Bytecode Compiler
Group: obsolete: 8.5.1
Status: Open
Resolution: None
Priority: 8
Private: No
Submitted By: Andreas Leitgeb (avl42)
>Assigned to: Jeffrey Hobbs (hobbs)
Summary: compiled regexp behaves differently

Initial Comment:
>From comp.lang.tcl: <slr...@ga...>

% set pattern --; set text ----
% regexp $pattern $text; # no error
1
% regexp -- ----   ; # error for same arguments.
wrong # args: should be "regexp ?switches? [...]"

This bug-report only documents the difference,
not which of the two is to be considered correct.


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>Comment By: miguel sofer (msofer)
Date: 2008-07-21 01:40

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This is tclguy's turf, I believe (and hope)

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Comment By: Don Porter (dgp)
Date: 2008-03-27 18:14

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dkf points out the roadblock case:

% regexp -about foo
0 {}
% set e -about
-about
% set s foo
foo
% regexp $e $s
0


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Comment By: Donal K. Fellows (dkf)
Date: 2008-03-27 18:09

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Be aware of the test regexp-20.2

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Comment By: Don Porter (dgp)
Date: 2008-03-12 03:35

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I agree that is the most sensible
way to define the behavior of this
command.

The snag is that the implementation
over many years *and the documentation*
disagree, saying that anything that
starts with "-" gets an attempt at
interpretation as a switch.

This is stupid, and it foils many
cases that could otherwise be compiled,
so I agree we should change it like
we changed [switch].

Just be ready for the same flood of
complaints we got about the [switch]
change.

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Comment By: Jeffrey Hobbs (hobbs)
Date: 2008-03-12 03:05

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I believe the 2nd variant (eval version) is what should be fixed.  The
extended info from wrong#args is:

wrong # args: should be "regexp ?switches? exp string ?matchVar?
?subMatchVar subMatchVar ...?"

This indicates 2 known required args, and 2 args are given to regexp.  Why
try to find errors when we can otherwise assume a regexp+2args == [regexp
$pat $str] at all times?


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Comment By: Don Porter (dgp)
Date: 2008-03-11 18:02

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That is, 1899962.

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Comment By: Don Porter (dgp)
Date: 2008-03-11 18:00

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This is the same issue as the compiled
two argument [switch].

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