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RE: Subs and Functions - 12/13/2006 8:36:38 AM
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ebgreen
Posts: 5246
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The return value is the only difference. There is no advantage of one over the other that I have ever been able to find. To be honest with you IMO it is silly for the language to have both.
_____________________________
"... when you are good and crazy, oooh, oooh, oooh, the sky is the limit!" - The Tick
Goog places to start:http://www.visualbasicscript.com/m_24727/tm.htm
http://www.visualbasicscript.com/m_47117/tm.htm
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RE: Subs and Functions - 12/14/2006 1:07:57 AM
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ebgreen
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I just think it is silly to have two different construct to do essentially the same thing. I prefer the way most other laguages handle it either by declaring a return in the function definition or always returning something and just making that something be nothing if you didn't really need a return at all. I suspect that my dislike for the way VBScript handles this issue comes from my desire to make code as re-useable as possible. I find that the use of subs for some reason tends to promote the use of global variables which decreases code re-useability.
_____________________________
"... when you are good and crazy, oooh, oooh, oooh, the sky is the limit!" - The Tick
Goog places to start:http://www.visualbasicscript.com/m_24727/tm.htm
http://www.visualbasicscript.com/m_47117/tm.htm
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RE: Subs and Functions - 12/14/2006 1:20:16 AM
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gdewrance
Posts: 587
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ginolard explained it to me like this
You assign a value to the Function itself (this was in answerto my question). You can't do that with a Sub.
There have been countless arguments on why people would even bother using Subs and, mostly, it comes down to code "cleanliness".
If you don't need to return a value, use a Sub.
If you do, use a Function (though that's not set in stone!).
One other thing, you might see people using the Call command when calling a Sub or Function. It's not always necessary.
All CALL does is tell the function it's calling to NOT return a value.
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RE: Subs and Functions - 12/14/2006 1:38:01 AM
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DiGiTAL.SkReAM
Posts: 1194
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Joined: 9/6/2005
From: Florida, USA
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I had read on some site that Subs were faster than Functions. Granted the difference was negligble, but I have never been able to validate this claim.
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"Would you like to touch my monkey?" - Dieter (Mike Meyers)
"It is better to die like a tiger, than to live like a pussy."
-Master Wong, from Balls of Fury
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RE: Subs and Functions - 12/14/2006 1:53:44 AM
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TNO
Posts: 1397
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quote:
One other thing, you might see people using the Call command when calling a Sub or Function. It's not always necessary.
All CALL does is tell the function it's calling to NOT return a value.
I'm not so sure about that. Every time I try to use an event listener Function from an HTML element I get an error if I don't use Call: "Can't use parenthesis when calling a Sub"
<edit>Almost forgot to mention. I have to use Call if using an objects method alot of times too Ex: oPopup.show("blah")</edit>
< Message edited by TNO -- 12/14/2006 1:57:43 AM >
_____________________________
To iterate is human, to recurse divine. -- L. Peter Deutsch
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RE: Subs and Functions - 12/14/2006 2:31:20 AM
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ebgreen
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quote:
Every time I try to use an event listener Function from an HTML element I get an error if I don't use Call: "Can't use parenthesis when calling a Sub"
Well, are you using () with a sub? If you are then lose the () and you shouldn't need Call. I have yet to find an instance where Call is required.
_____________________________
"... when you are good and crazy, oooh, oooh, oooh, the sky is the limit!" - The Tick
Goog places to start:http://www.visualbasicscript.com/m_24727/tm.htm
http://www.visualbasicscript.com/m_47117/tm.htm
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RE: Subs and Functions - 12/14/2006 4:34:09 AM
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TNO
Posts: 1397
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From: thenewobjective.com
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Yum....global variables....
I dont see the logic behind recreating an object each time I want to display it.
_____________________________
To iterate is human, to recurse divine. -- L. Peter Deutsch
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RE: Subs and Functions - 12/14/2006 4:40:53 AM
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ebgreen
Posts: 5246
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I wouldn't recreate it either. I would pass it into the func. That way I can drop the func into any other script that I want and the definition clearly shows me what I need to have to make the function work.
_____________________________
"... when you are good and crazy, oooh, oooh, oooh, the sky is the limit!" - The Tick
Goog places to start:http://www.visualbasicscript.com/m_24727/tm.htm
http://www.visualbasicscript.com/m_47117/tm.htm
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RE: Subs and Functions - 12/14/2006 5:46:22 AM
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TNO
Posts: 1397
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Joined: 12/18/2004
From: thenewobjective.com
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But why on earth would I have to use call for a function? Is it because its a method of an object? This isn't making any sense....
_____________________________
To iterate is human, to recurse divine. -- L. Peter Deutsch
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RE: Subs and Functions - 12/14/2006 7:42:21 AM
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TNO
Posts: 1397
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From: thenewobjective.com
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Hence my dilemma. This is not the case in all instances as I've shown in my example. If I remove call from window.createPopup.show() It will throw an exception regardless of the fact that it is a function.
Belated Note: window.createPopup() MUST remain outside of functions or it will not work without irrational behavior (failure to display, partial display, incorect display, etc.)
_____________________________
To iterate is human, to recurse divine. -- L. Peter Deutsch
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RE: Subs and Functions - 12/14/2006 8:08:56 AM
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ehvbs
Posts: 2220
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From: Germany
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Sometimes you want to have something done and are not interested in getting
information: Let's say you want to startle the user. You use a Sub (or - if the
compiler and the runtime system are a bit more flexible than Pascal - you use
a versatile NamedCodeBlock AS a Sub):
MsgBox "Pay attention!", vbAbortRetryIgnore
Other VBScript Programmers (including you) and the compiler know you won't use
the virtual/possible information about clicked buttons, because
you didn't assign to a variable
you didn't put parameter list () around the arguments
Sometimes you need information. You call a function (or a NamedCodeBlock
that can be called AS a function) to do that:
iRet = MsgBox( "Pay attention!", vbAbortRetryIgnore )
.... many lines of code ....
If vbOk = iRet Then
(sorry about the iRet, but I can't come up with a suitable name just now).
Doing the first thing in a language that only has/allows functions, you
must write
iDummy = MsgBox( "Pay attention!", vbAbortRetryIgnore )
do to the first thing - and worry whether iDummy will be used at other
places in your program; another programmer (or you in about 5 weeks) will
have to scan your code to make sure - all your code if you don't heed
ebgreen's advice to shun global variables. That's why I objected to his
proposal to have functions only.
The Call statement is provided as an additional way to call a function
AS a Sub:
Call MsgBox( "Pay attention!", vbAbortRetryIgnore )
You are not allowed to drop the (), because Call needs a function to call
to discard its return value. Now one of the high priority aims of VBScript
is to let even starting/inexperienced/sloppy programmers succeed (definitely
no irony intented, there is not so much difference to the highly acclaimed
mission statements of Perl: "Making Easy Things Easy and Hard Things Possible"
and "Do The Right Thing"). That's the reason you can use Call to call something
that is definitely a Sub - as long as you help the compiler/parser a little
bit: you'll have to use those ()
Call MySub( 1, 2, 3 )
which will be "VERBOTEN" if you drop the unnecessary "Call":
MySub( 1, 2, 3 ) ' don't expect this to work
But - you'll code:
MsgBox( "But I *can* use ()!" )
Yes, it works; but those () aren't parameter list (), but "please pass per
value" parantheses, that - by nature and definition - can be put around
just one element.
Add to this that the VBScript Docs WRONGLY put parameter list () all over the
place - probably the docs and/or the documenters were infected with a heavy
dose of Javascript - it's no wonder, Subs, Functions, and () aren't easy to
get right in VBScript.
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RE: Subs and Functions - 12/14/2006 8:10:51 AM
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TNO
Posts: 1397
Score: 16
Joined: 12/18/2004
From: thenewobjective.com
Status: offline
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Alright, I did a little more research and this is what came up with:
Subroutine Code Structure
If a subroutine does not receive any arguments, then you do not use any parentheses when declaring the subroutine. Note the required use of the Sub and End Sub statements which define the start and finish of the subroutine code.
Sub MySubroutine
'place your code here
End Sub
However, if a subroutine does receive arguments, then you must use parentheses in its declaration. If there is more than one argument, you must separate the arguments with commas.
Sub MySubroutine(intUsageFee, intTimeInHours, strCompanyName)
'place your code here
End Sub
Function Code Structure
As with subroutines, if a function does not receive any arguments, then you do not use any parentheses in the function declaration. Note the required use of the Function and End Function statements which define the start and finish of the function code.
Function MyFunction
'place your code here
End Function
However, if a function does receive arguments, then you must enclose its argument list in parentheses when declaring the function. If there is more than one argument, you must separate the arguments with commas.
Function MyFunction(intUsageFee, intTimeInHours, strCompanyName)
'place your code here
End Function
Calling the Subroutine
There are two possible ways to call a subroutine. You may either call the subroutine directly by name only, or you may call it by using the VBScript Call statement.
Calling a Subroutine by Name
If a subroutine does not pass any arguments, then you do not use any parentheses.
MySubroutine
Even if a subroutine has arguments, you still do not use parentheses. If there is more than one argument, you must separate the arguments with commas. If you enclose the argument list in parentheses when attempting to call a subroutine that takes more than one argument, you will receive the runtime error "Cannot use parentheses when calling a Sub".
MySubroutine intUsageFee, intTimeInHours, "Blah"
Using the VBScript Call Statement to Call a Subroutine
The use of Call statement is optional when you wish to call a subroutine. The purpose of the Call statement when used with a Sub is to allow you to enclose the argument list in parentheses. However, if a subroutine does not pass any arguments, then you still should not use parentheses when calling a Sub using the Call statement.
Call MySubroutine
If a subroutine has arguments, you must use parentheses when using the Call statement. If there is more than one argument, you must separate the arguments with commas.
Call MySubroutine(intUsageFee, intTimeInHours, "blah")
Calling the Function
There are two possible ways to call a function. You may either call the function directly, by name only, or you may call it by using the VBScript Call statement.
Calling a Function by Name
When calling a function directly by name and when there is no assignment to a returned value, all of the following are legal syntax:
MyFunction
MyFunction()
MyFunction intUsageFee, intTimeInHours, "blah"
If you want a returned value, you can assign the function to a variable. Note that if there is one or more arguments, you must use the parentheses.
returnval = MyFunction
returnval = MyFunction()
returnval = MyFunction(intUsageFee, intTimeInHours, "blah")
Using the Call Statement
If a function has arguments, you must use parentheses when using the Call statement. If there is more than one argument, you must separate the arguments with commas. There is no returned value when using Call.
Call MyFunction(intUsageFee, intTimeInHours, "Blah")
_____________________________
To iterate is human, to recurse divine. -- L. Peter Deutsch
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RE: Subs and Functions - 12/14/2006 8:15:50 AM
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TNO
Posts: 1397
Score: 16
Joined: 12/18/2004
From: thenewobjective.com
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heh, we cross-posted
_____________________________
To iterate is human, to recurse divine. -- L. Peter Deutsch
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