Avoidinig globals

7 Mar 2005 8:14 PM

Tim

Is there a way to force a sub to only use global variables when
explicitly told to?

I mean that if I forget to dim a a local variable but there is already
such a variable in the global scope then my function will use the global
variable without me intending it too.

Here is an example:

<html>
   <% Option Explicit
     sub corect()
       Dim var
       var=5
     end sub

     sub wrong()
       var=5
     end sub

     Dim var
     var=2
     response.write(var) 'prints rightly 2
     call corect()
     response.write(var) 'Still prints rightly 2
     call wrong()
     response.write(var) 'Now it prints 5 because I forgott to Dim var
   %>
<html>

I would have liked to be able to declare a Globals Explicit this should
force me to write

     sub wrong()
       global var=5
     end sub

If I wanted wrong to change the behavior of the globaly defined variable
var.

Is there a way to acomplish this in ASP?

Thanks

Tim

7 Mar 2005 11:15 PM

Mark Schupp

Either don't use globals at all (as in following example) or use a naming
convention for global variables like "g_var" so that you only use them
intentionally in subroutines.

<%@ Language=VBScript %>
<%
option explicit

call main

Sub Main()
     Dim var
     var=2
     response.write(var) 'prints rightly 2
     call corect()
     response.write(var) 'Still prints rightly 2
     call wrong()
     response.write(var) 'Now it prints 5 because I forgott to Dim var
End Sub

sub corect()
Dim var
var=5
end sub

sub wrong()
var=5
end sub
%>

--
--Mark Schupp
Head of Development
Integrity eLearning
www.ielearning.com

Show quote

"Tim" <a*@gahnstrom.se> wrote in message
news:MC2Xd.19099$d5.146369@newsb.telia.net...
> Is there a way to force a sub to only use global variables when explicitly
> told to?
>
> I mean that if I forget to dim a a local variable but there is already
> such a variable in the global scope then my function will use the global
> variable without me intending it too.
>
> Here is an example:
>
> <html>
>   <% Option Explicit
>     sub corect()
>       Dim var
>       var=5
>     end sub
>
>     sub wrong()
>       var=5
>     end sub
>
>     Dim var
>     var=2
>     response.write(var) 'prints rightly 2
>     call corect()
>     response.write(var) 'Still prints rightly 2
>     call wrong()
>     response.write(var) 'Now it prints 5 because I forgott to Dim var
>   %>
> <html>
>
> I would have liked to be able to declare a Globals Explicit this should
> force me to write
>
>
>     sub wrong()
>       global var=5
>     end sub
>
> If I wanted wrong to change the behavior of the globaly defined variable
> var.
>
> Is there a way to acomplish this in ASP?
>
> Thanks
>
> Tim

8 Mar 2005 7:48 AM

Tim

Mark Schupp wrote:

> Either don't use globals at all (as in following example) or use a naming
> convention for global variables like "g_var" so that you only use them
> intentionally in subroutines.

Both solutions are workable but none are really good I think.

But if there is not globals explicit kind of directive I guess they are
as good as they will be.

Thanks

Tim

8 Mar 2005 11:17 AM

Phill. W

"Tim" <a*@gahnstrom.se> wrote in message
news:MC2Xd.19099$d5.146369@newsb.telia.net...
> I mean that if I forget to dim a a local variable but there is already
> such a variable in the global scope then my function will use the
> global variable without me intending it too.

Welcome to the World of Naming Conventions.

There are those who sneer at prefixes of /any/ kind on variable
names, because they know (or, rather, their mega-expensive
IDE tells them) what DataType a variable is and whether it's
Private, Public, Global or whatever.

Those of us in the Real World, who still have to fight the Good
Fight [occasionally] with the likes of Notepad prefer to be able
to read this kind of thing for ourselves.

At the /very/ least, include a "Scope" prefix on your variable names,
as in

iCount ' [local] Integer variable
smCount ' String Variable [at *M*odule (or class) level]
lgCount ' Long variable [*G*lobal]

That way, you /can't/ get your variables mixed up.

HTH,
Phill W.

8 Mar 2005 5:20 PM

Tim

Phill. W wrote:
Show quote

> "Tim" <a*@gahnstrom.se> wrote in message
> news:MC2Xd.19099$d5.146369@newsb.telia.net...
>
>>I mean that if I forget to dim a a local variable but there is already
>>such a variable in the global scope then my function will use the
>>global variable without me intending it too.
>
>
> Welcome to the World of Naming Conventions.

> At the /very/ least, include a "Scope" prefix on your variable names,
> as in
>
> iCount ' [local] Integer variable
> smCount ' String Variable [at *M*odule (or class) level]
> lgCount ' Long variable [*G*lobal]
>
> That way, you /can't/ get your variables mixed up.

It sure helps but it is not fool proof, atleast not when I am the fool
in question.

I start the project out as a single page and use global variables
(reasonable).

When the project grows I realize I should move some stuf to functions
and / or include files. Then I copy and past code and all the names come
a long.

Of course, then I should go through my copied code and change the
prefixes but if I miss one variable there is a rather hard to find error
in my code.

A globals explicit would help prevent this kind of errors (or at least
make them easy to spot). To me it is such an obviously good feature I
assumed it should be in there somewhere but I realize I cannot get what
is not there :(

Tim