[Tcl-bugs] [ tcl-Bugs-1445454 ] incr on undefined array fails in procedures

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Bugs item #1445454, was opened at 2006-03-08 05:30
Message generated for change (Comment added) made by msofer
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Category: 46. Bytecode Compiler
Group: current: 8.5a3
Status: Open
Resolution: None
Priority: 9
Submitted By: Andreas Leitgeb (avl42)
Assigned to: miguel sofer (msofer)
Summary: incr on undefined array fails in procedures

Initial Comment:
on a fresh tclsh8.5:
% incr foo(1)
1
# so far so good, but:
% proc abc {} { incr foo(1) }
% abc
can't read "foo(1)": no such variable

(with scalars it works both ways)


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>Comment By: miguel sofer (msofer)
Date: 2006-03-08 06:58

Message:
Logged In: YES 
user_id=148712

Note that the problem is the non-existing array, and not the
non-existing component:

% proc x {} {incr a(1)}
% proc y {} {set a(2) 1; incr a(1)}
% x
can't read "a(1)": no such variable
% y
1


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Comment By: Donal K. Fellows (dkf)
Date: 2006-03-08 06:02

Message:
Logged In: YES 
user_id=79902

Looks to be a difference in behaviour between bytecodes. :-(

% set tcl_traceExec 3; time {incr foo(1)}; set tcl_traceExec 0
1: (10) invoking "time" "incr foo(1)"

Executing ByteCode 0x814d960, refCt 2, epoch 0, interp
0x8158d50 (epoch 0)
  Source: "incr foo(1)"
  Cmds 1, src 11, inst 7, litObjs 2, aux 0, stkDepth 2,
code/src 10.91
  Code 120 = header 100+inst 7+litObj 8+exc 0+aux 0+cmdMap 4
  Starting stack top=1
 2:  1 (0) push1 0      # "foo"
 2:  2 (0) push1 0 => "foo"
 2:  2 (2) push1 1      # "1"
 2:  3 (2) push1 1 => "1"
 2:  3 (4) incrArrayStkImm +1
 2:  3 (4) incrArrayStkImm "foo(1)" (by 1) => 1
 2:  2 (6) done
 2:  2 (6) done => return code=0, result="1"

   ... no enclosing catch, returning TCL_OK
0
% set tcl_traceExec 3;catch { abc }; set tcl_traceExec 0
1: (18) invoking "abc"
Calling proc "abc"

Executing ByteCode 0x814d260, refCt 2, epoch 0, interp
0x8158d50 (epoch 0)
  Source: "incr foo(1)"
  Cmds 1, src 11, inst 6, litObjs 1, aux 0, stkDepth 1,
code/src 10.91
  Code 120 = header 100+inst 6+litObj 4+exc 0+aux 0+cmdMap 4
  Proc 0x816fb90, refCt 2, args 0, compiled locals 1
  Starting stack top=24
 2: 24 (0) push1 0      # "1"
 2: 25 (0) push1 0 => "1"
 2: 25 (2) incrArray1Imm %v0 +1         # var "foo"
 2: 25 (2) incrArray1Imm 0 "1" (by 1) => ERROR: can't read
"foo(1)": no such v
   ... no enclosing catch, returning TCL_ERROR
0


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