[Tcl-bugs] [ tcl-Bugs-2007198 ] eval after regexp fails unless followed by a puts

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Bugs item #2007198, was opened at 2008-07-01 01:03
Message generated for change (Comment added) made by ferrieux
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Category: 43. Regexp
Group: current: 8.5.3
Status: Open
Resolution: None
>Priority: 7
Private: No
Submitted By: Nobody/Anonymous (nobody)
>Assigned to: miguel sofer (msofer)
Summary: eval after regexp fails unless followed by a puts

Initial Comment:
Version tcl8.5-thread-linux-x86_64 downloaded 2008-06-12.
OS Fedora 9
Old program suddenly fails on this system.  Here is a snippet that when run via wish8.5 fails with an error in the eval command.  But when the next line puts is uncommented it performs the eval with no error.
###########################################3
set fong "--EVAL set wrap 490"
while { 1 } {
 catch {
  if { [regexp {^--EVAL(.*)} $fong waste fong ] } {
    puts "fong was an EVAL"
    eval $fong
#####  Uncomment the next command and the eval works
#####  correctly
#puts -nonewline ""
    continue}
  puts "Went on past"
  continue
  } error
  if { $error != "" } {
    puts "There was an error, the catch value is $error"
    exit
   }
  puts "exiting with wrap set to $wrap"
  exit
 }



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>Comment By: Alexandre Ferrieux (ferrieux)
Date: 2008-07-01 01:30

Message:
Logged In: YES 
user_id=496139
Originator: NO

Hmmm, half a red herring there.
First, notice that checking the value of the 2nd arg to [catch] without
checking its return value is bad practice (possible collisions).
Second, the whole report can be simplified to the following:

        set ev {set x 12}
        catch {eval $ev;continue} y
        puts $y ==> 12
        catch {eval {set x 13};continue} y
        puts $y ==> 

Have to check about the contract of [continue] (is it supposed to reset
the interp's result ?)
But indeed the impact of a dynamic eval is strange. Possibly an effect of
compilation ?
Since this is rather linked to basic execution than regexp, reassigning to
Miguel.



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