Tcl Source Code

[namespace which -variable ary(i)] returns a null 
string even when ary(i) exists! This is a major pain
when trying to get fully scoped variable names to give 
to widgets. Here is a script snippet that shows the 
eror:

Sebres wrote:

I guess, it should rather return "" in this case, because currently "namespace which" will never produce an error (by valid command syntax).

You are right. Personnally, I can not understand the usage for this. I would like to have an error instead of an empty return.

Thats why I did not find a bug for monthes. I wrote:

ttk::radiobutton ... -variable [namespace which -variable a(b)]

Clearly an error, but no error raised and it just does not work.

Thanks, Harald

check if it is an array. If not -> error

unset -nocomplain novar
namespace which -variable novar

Miquel Sofer wrote:

(2) It's not so clear to me what the correct fix would be:
what should happen if the array itself exists, but the array
element does not? In your script, what is the expected
result of adding a line
   puts "4 - [namespace which -variable ary(k)]"
According to the man page, the return should be "" - is this
what you're expecting?

Let me express my expectation. [namespace which -variable ary(k)] should do the following:

• resolve "ary" in the local scope
• check if it is an array. If not -> error
• format the result the same way as [namespace which -variable ary](k). This means, that the existence of the given array index must not exist and is not relevant. The existance of the array and its scope is important.

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This cannot be fixed at reasonable cost without changing the
Var struct: an array element does not know it's containing
array, even though it knows its hashtable.

This will probably not happen until Tcl9. Leaving the bug
open to fix at that time.

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(1) Sorry, this bug somehow flew under my horizon :( 

(2) It's not so clear to me what the correct fix would be:
what should happen if the array itself exists, but the array
element does not? In your script, what is the expected
result of adding a line
   puts "4 - [namespace which -variable ary(k)]"
According to the man page, the return should be "" - is this
what you're expecting?

(3) Depending on the answer to (2), a workaround involving
[info exists] may be the solution for now.

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Got submitted to quick...
namespace eval a {
  variable ary
  set ary(i) v
  puts "1 - [namespace which -variable ary]"
  set x ary
  set y ary(i)
  puts "2 - [namespace which -variable $x]"
  puts "3 - [namespace which -variable $y]"
 }