VB6 Scope Issues

Andrew Chalk · Joined: 04 Oct 2007 Posts: 15

1) What is the difference in scope of:
Public X As String
Global X As String

2) What is the difference in scope of:
Private Sub S()
Sub S()

In (2): Nothing, I believe. The absence of a scope qualifier on a Sub or
Function implies Private, right?

Many thanks.

Archived from group: microsoft>public>vb>syntax

Bob O`Bob · Joined: 04 Oct 2007 Posts: 1456

Andrew Chalk wrote:
> 1) What is the difference in scope of:
> Public X As String
> Global X As String

Anywhere where the latter is not a syntax error, there is no difference between the two.

Anywhere else (place where you can only use Public) it /is/ actually rather different
from *either* of the above.

>
> 2) What is the difference in scope of:
> Private Sub S()
> Sub S()
>
> In (2): Nothing, I believe. The absence of a scope qualifier on a Sub or
> Function implies Private, right?

I think that's the case, but it's not something I'm likely to ever bother to test.
VB has, over the years, given me a serious distaste for defaults.

Bob
--

Andrew Chalk · Joined: 04 Oct 2007 Posts: 15

"Bob O`Bob" wrote in message @TK2MSFTNGP03.phx.gbl...
> Andrew Chalk wrote:
>> 1) What is the difference in scope of:
>> Public X As String
>> Global X As String
>
>
> Anywhere where the latter is not a syntax error, there is no difference
> between the two.
>
> Anywhere else (place where you can only use Public) it /is/ actually
> rather different
> from *either* of the above.
>
Can you explain the last sentence? It is not clear what the "it" refers to.

Thanks.

Andrew Chalk · Joined: 04 Oct 2007 Posts: 15

"Bob O`Bob" wrote in message @TK2MSFTNGP03.phx.gbl...
>> 2) What is the difference in scope of:
>> Private Sub S()
>> Sub S()
>>
>> In (2): Nothing, I believe. The absence of a scope qualifier on a Sub or
>> Function implies Private, right?
>
> I think that's the case, but it's not something I'm likely to ever bother
> to test.
> VB has, over the years, given me a serious distaste for defaults.
>
I agree. As a newbie to VB I wanted to explicitly write "Private" if that
was the default.

Thanks,

Andrew

Bob O`Bob · Joined: 04 Oct 2007 Posts: 1456

Andrew Chalk wrote:
> "Bob O`Bob" wrote in message
> @TK2MSFTNGP03.phx.gbl...
>> Andrew Chalk wrote:
>>> 1) What is the difference in scope of:
>>> Public X As String
>>> Global X As String
>>
>> Anywhere where the latter is not a syntax error, there is no difference
>> between the two.
>>
>> Anywhere else (place where you can only use Public) it /is/ actually
>> rather different
>> from *either* of the above.
>>
> Can you explain the last sentence? It is not clear what the "it" refers to.

In a standard or "code" module (file extension "bas") the two lines are
precisely equivalent, and either one actually instantiates the variable.

In a class or form module the Global declaration is illegal and the Public
declaration creates a property which requires a reference to an instance
before it actually means anything at all.

.... which is why I've established a /personal/ standard to NEVER use Public
where Global is legal. That way at least in /my/ code each keyword
[pretty much] always means the same thing. Some folks have argued that
the Global keyword is "deprecated" and should be replaced by Public,
but I most emphatically disagree.

Bob
--

argusy · Joined: 04 Oct 2007 Posts: 145

Hi, Bob
I agree wholeheartedly with your last paragraph. If I know a variable is going
to be used throughout a program, and it is NOT specific to a module operation,
I'll declare globally.

For example, a boolean variable to flag a condition

public function
flag = false 'declared globally

do

if aCondition is true then flag = true
loop
if flag = false then doSomeOtherThing 'weak I know, could use it above
exit sub

I **could** have declared 'flag' as a local boolean variable
(dim flag as boolean)
and it disappears from scope when the function has ended.
or as a form variable
(public flag as boolean)
and then it disappears when the form is unloaded

PROVIDED I declare its condition before I use it, I don't see any problem
(If I didn't, and it has been set elsewhere, it could stuff up the logic within
this function - which is a good reason to declare it inside the function, isn't
it?. Hmmm. Bad choice, off the top of my head, but it serves the purpose for
Andrew's query)

Argusy

Bob O`Bob wrote:
> Andrew Chalk wrote:
>
>> "Bob O`Bob" wrote in message
>> @TK2MSFTNGP03.phx.gbl...
>>
>>> Andrew Chalk wrote:
>>>
>>>> 1) What is the difference in scope of:
>>>> Public X As String
>>>> Global X As String
>>>
>>>
>>> Anywhere where the latter is not a syntax error, there is no
>>> difference between the two.
>>>
>>> Anywhere else (place where you can only use Public) it /is/ actually
>>> rather different
>>> from *either* of the above.
>>>
>> Can you explain the last sentence? It is not clear what the "it"
>> refers to.
>
>
> In a standard or "code" module (file extension "bas") the two lines are
> precisely equivalent, and either one actually instantiates the variable.
>
> In a class or form module the Global declaration is illegal and the Public
> declaration creates a property which requires a reference to an instance
> before it actually means anything at all.
>
>
> ... which is why I've established a /personal/ standard to NEVER use Public
> where Global is legal. That way at least in /my/ code each keyword
> [pretty much] always means the same thing. Some folks have argued that
> the Global keyword is "deprecated" and should be replaced by Public,
> but I most emphatically disagree.
>
>
>
>
> Bob

Andrew Chalk · Joined: 04 Oct 2007 Posts: 15

Got it.

Thanks!

"Bob O`Bob" wrote in message @TK2MSFTNGP02.phx.gbl...
> Andrew Chalk wrote:
>> "Bob O`Bob" wrote in message
>> @TK2MSFTNGP03.phx.gbl...
>>> Andrew Chalk wrote:
>>>> 1) What is the difference in scope of:
>>>> Public X As String
>>>> Global X As String
>>>
>>> Anywhere where the latter is not a syntax error, there is no difference
>>> between the two.
>>>
>>> Anywhere else (place where you can only use Public) it /is/ actually
>>> rather different
>>> from *either* of the above.
>>>
>> Can you explain the last sentence? It is not clear what the "it" refers
>> to.
>
> In a standard or "code" module (file extension "bas") the two lines are
> precisely equivalent, and either one actually instantiates the variable.
>
> In a class or form module the Global declaration is illegal and the Public
> declaration creates a property which requires a reference to an instance
> before it actually means anything at all.
>
>
> ... which is why I've established a /personal/ standard to NEVER use
> Public
> where Global is legal. That way at least in /my/ code each keyword
> [pretty much] always means the same thing. Some folks have argued that
> the Global keyword is "deprecated" and should be replaced by Public,
> but I most emphatically disagree.
>
>
>
>
> Bob
> --

Karl E. Peterson · Joined: 04 Oct 2007 Posts: 4836

Andrew Chalk wrote:
> "Bob O`Bob" wrote in message
> @TK2MSFTNGP03.phx.gbl...
>>> 2) What is the difference in scope of:
>>> Private Sub S()
>>> Sub S()
>>>
>>> In (2): Nothing, I believe. The absence of a scope qualifier on a
>>> Sub or Function implies Private, right?
>>
>> I think that's the case, but it's not something I'm likely to ever
>> bother to test.
>> VB has, over the years, given me a serious distaste for defaults.
>
> I agree. As a newbie to VB I wanted to explicitly write "Private" if
> that was the default.

Wise instinct. Because Public is actually the default.

Very easy to test. In a FRM file:

Private Sub Command1_Click()
test
End Sub

In a BAS file:

Sub test()
Debug.Print "test"
End Sub

Run, press Command1.
--
Working without a .NET?
http://classicvb.org/

OCX issues (My apologies if this message has already been posted. I tried earlier and it didn't seem to make it to the NG) I have an OCX that is used to interface to a camera. It was written in-house. IN VB6, under components, I now have three of the same entry. I w

VB / DLL Issues I'm running a device driver DLL from my VB program. Each time I want to access the device, I run an Initialize command to the driver then go about my business reading data and when I am finished with the device I issue a Kill command to the driver. The

VB .NET Upgrade Issues Hi, all I tried to open a VB6 project in VB .NET, which invokes the upgrade engine, and after upgrading, it dumped me with this list of upgrade errors. The project that I tried to open is an example taken from MS directX8.1 SDK vbexamples folder (called P

Version Issues I downloaded what I thought was the latest version of the DirectX 9.0 SDK - The Summer Update 2003 with 9.0b, but when I try to run anything it complains that the pre- release version od DirectX is expired. How can I tell which is the proper SDK download

PCAnywhere OLE issues... I'm trying to use PCAnywhere in my application to transfer files and execute remote commands. I originally tried using the command queue but this won't really work for me because the paths I'm sending and receiving from are not going to remain the same.