Automatically Exporting Global Variables - TCL
arij...@gmail.com
Consider this code:
set my_global_var "arijit"
proc my_proc {} {
puts $my_global_var;
}
my_proc
In this code, I have a constraint that I cannot have a "global
my_global_var" statement inside 'my_proc' proc.
With that constraint, is there any way in TCL by which I can instruct
TCL to lookup for global variables automatically.
I mean, given a variable usage, see if it is defined locally. If not,
check for global defination like C/C++.
Is there any way I can get this behavior in TCL (without explicitly
saying that my_global_var is global using "global my_global_var")?
My appologies, if this is not the right forum to ask this question.
Thanks
Arijit
Helmut Giese
>Am a beginner in TCL. Need a quick help...
>
>Consider this code:
>
>set my_global_var "arijit"
>
>proc my_proc {} {
> puts $my_global_var;
>}
>
>my_proc
>
>In this code, I have a constraint that I cannot have a "global
>my_global_var" statement inside 'my_proc' proc.
>
>With that constraint, is there any way in TCL by which I can instruct
>TCL to lookup for global variables automatically.
No - well, not that I know of.
The easiest thing would be to say
proc my_proc {} {
puts $::my_global_var
}
and in case your constraint prohibits this, too (care to tell what
this constraint is?) you could explicitly jump into global scope like
proc my_proc {} {
uplevel #0 {puts $my_global_var}
}
HTH
Helmut Giese
Bruce Hartweg
> Am a beginner in TCL. Need a quick help...
>
> Consider this code:
>
> set my_global_var "arijit"
>
> proc my_proc {} {
> puts $my_global_var;
> }
>
> my_proc
>
> In this code, I have a constraint that I cannot have a "global
> my_global_var" statement inside 'my_proc' proc.
why on earth is that constraint imposed?
>
> With that constraint, is there any way in TCL by which I can instruct
> TCL to lookup for global variables automatically.
>
no (well, maybe by cheating*)
> I mean, given a variable usage, see if it is defined locally. If not,
> check for global defination like C/C++.
>
tcl is not C/C++
> Is there any way I can get this behavior in TCL (without explicitly
> saying that my_global_var is global using "global my_global_var")?
>
no, but if you know it is global you can be explicit
$::my_global_var
which avoids the actual use of the global command
> My appologies, if this is not the right forum to ask this question.
>
correct forum for sure.
> Thanks
> Arijit
>
*the cheat
override the proc command to automatically insert the global command
as the proc is being defined - that way you don;t have the global in you
codebase, but it is there at runtime.
Bruce
Cameron Laird
.
.
There are several approaches, depending on what you're after.
Does
set my_global_var "arijit"
proc my_proc {} {
}
my_proc
meet your needs?
If not, it sounds as though you want your proc to behave differ-
ently from the built-in proc. That's not too hard; is it indeed
what you're after?
suchenwi
variables that exist at the time of call are in the proc's local
scope, by augmenting :
rename proc _proc
_proc proc {name argl body} {
_proc $name $argl "eval global \[info globals\]\n$body"
}
Testing:
% proc try x {return $x$tcl_version}
% try it
it8.4
But this is a questionable trick. The separation of globals and locals
has good reasons, and locals are to be preferred whenever possible
(faster, need less memory, have no side effects).
Gerald W. Lester
> Am a beginner in TCL. Need a quick help...
>
> Consider this code:
>
> set my_global_var "arijit"
>
> proc my_proc {} {
> puts $my_global_var;
> }
>
> my_proc
>
> In this code, I have a constraint that I cannot have a "global
> my_global_var" statement inside 'my_proc' proc.
Where does this constraint come from -- your teacher or your boss?
If it is your boss, then you need to post the exact constraint language
because it maybe saying more or less then you think -- or better yet ask him
how you should be doing it (I'm sure it will get pointed out during the code
review if you go off on a tangent from the company accepted policy).
It is from your teacher, I fear he was looking for you to use namespace
referencing -- in which case other posters have already done your homework
for you.
BTW, in either case since you appear hesitant to ask your boss/teacher the
question, what makes you think they are not reading c.l.t?
--
+--------------------------------+---------------------------------------+
| Gerald W. Lester |
|"The man who fights for his ideals is the man who is alive." - Cervantes|
+------------------------------------------------------------------------+
Donald Arseneau
> In this code, I have a constraint that I cannot have a "global
> my_global_var" statement inside 'my_proc' proc.
Oh boy, a puzzle game.
upvar #0 my_global_var my_global_var
is my entry