[Tcl-bugs] [ tcl-Bugs-2142989 ] add examples to the [catch] man page

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Bugs item #2142989, was opened at 2008-10-02 16:32
Message generated for change (Comment added) made by msofer
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Category: None
Group: None
Status: Open
>Resolution: None
>Priority: 3
Private: No
Submitted By: Nobody/Anonymous (nobody)
>Assigned to: miguel sofer (msofer)
>Summary: add examples to the [catch] man page

Initial Comment:
I use tcl-8.5.4.

In the following code 'catch' returns 1 indicating an error but '::errorInfo' isn't set, producing 'no such variable' message.


--- testcase ---
proc c {} {}
proc main {} {
  if {[catch { return [c] }]} {
    puts "ERROR: *$::errorInfo* *************"
  }
}
main

--- output ----
can't read "::errorInfo": no such variable
    while executing
"puts "ERROR: *$::errorInfo* *************""


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>Comment By: miguel sofer (msofer)
Date: 2008-10-02 19:07

Message:
Catch can return a lot of other codes - essentially, any 32-bit integer
value:
 % catch {return -code 1234 -level 0}
 1234
If you have a suggestion on how to improve the man page and examples,
please add it here.

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Comment By: Yuri (yurivict)
Date: 2008-10-02 18:43

Message:
Makes sense: 'catch' has 5 possible return values (0..4).

Then I suggest you add another example of basic 'catch' usage in EXAMPLES
section of catch(n) demonstrating all 5 return values.
Otherwise people look at the example (if {[catch...]} {...exit...}) and
get misled by it's simplicity.

----------------------------------------------------------------------

Comment By: miguel sofer (msofer)
Date: 2008-10-02 16:46

Message:
Wrong diagnostic: [catc] is not returning 1 (error) but 2 (return); no
error, no errorInfo ...
 mig@oli:~$ tclsh
 % proc c {} {}
 % catch {return [c]}
 2


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