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[smlnj] Diff of /sml/trunk/NOTES/HISTORY
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Diff of /sml/trunk/NOTES/HISTORY

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revision 677, Mon Jun 26 00:56:56 2000 UTC revision 678, Tue Jun 27 07:51:09 2000 UTC
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13  Description:  Description:
14  ----------------------------------------------------------------------  ----------------------------------------------------------------------
15  Name: Matthias Blume  Name: Matthias Blume
16    Date: 2000/06/27 16:51:00 JST
17    Tag: blume-20000627-noweb
18    Description:
19    
20    Changes:
21    
22     1. Implemented "subdir" and "witness" options for noweb tool.
23        This caused some slight internal changes in CM's tool implementation.
24     2. Fixed bug in "tool plugin" mechanism.  This is essentially cleaning
25        some remaining issues from earlier path anchor changes.
26     3. Updated CM manual accordingly.
27    
28     4. Changed implementation of back-tracing so that I now consider it
29        ready for prime-time.
30    
31        In particular, you don't have to explicitly trigger the back-trace
32        anymore.  Instead, if you are running BTrace-instrumented code and
33        there is an uncaught exception (regardless of whether or not it was
34        raised in instrumented code), the top-level evalloop will print
35        the back-trace.
36    
37        Features:
38    
39          - Instrumented and uninstrumented code work together seemlessly.
40            (Of course, uninstrumented code is never mentioned in actual
41             back-traces.)
42    
43          - Asymptotic time- and space-complexity of instrumented code is
44            equal to that of uninstrumented code.  (This means that
45            tail-recursion is preserved by the instrumentation phase.)
46    
47          - Modules whose code has been instrumented in different sessions
48            work together without problem.
49    
50          - There is no penalty whatsoever on uninstrumented code.
51    
52          - There is no penalty on "raise" expressions, even in
53            instrumented code.
54    
55        A potential bug (or perhaps it is a feature, too):
56    
57          A back-trace reaches no further than the outermost instrumented
58          non-trivial "raise".  Here, a "trivial" raise is one that is the
59          sole RHS of a "handle" rule.  Thus, back-traces reach trough
60    
61               <exp> handle e => raise e
62    
63          and even
64    
65               <exp> handle Foo => raise Bar
66    
67          and, of course, through
68    
69               <exp> handle Foo => ...
70    
71         if the exception was not Foo.
72    
73         Back-traces always reach right through any un-instrumented code
74         including any of its "handle" expressions, trivial or not.
75    
76       To try this out, do the following:
77    
78         - Erase all existing binfiles for your program.
79           (You may keep binfiles for those modules where you think you
80            definitely don't need back-tracing.)
81         - Turn on back-trace instrumentation:
82              SMLofNJ.Internals.BTrace.mode (SOME true);
83         - Recompile your program.  (I.e., run "CM.make" or "use".)
84         - You may now turn instrumentation off again (if you want):
85              SMLofNJ.Internals.BTrace.mode (SOME false);
86         - Run your program as usual.  If it raises an exception that
87           reaches the interactive toplevel, then a back-trace will
88           automatically be printed.  After that, the toplevel loop
89           will print the exception history as usual.
90    
91    ----------------------------------------------------------------------
92    Name: Matthias Blume
93  Date: 2000/06/26 09:56:46 JST  Date: 2000/06/26 09:56:46 JST
94  Tag: blume-20000626-setup  Tag: blume-20000626-setup
95  Description:  Description:

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