Hi,
I am a VB.net beginner, I do not know what are the major difference between
Module vs Class.
Could someone guide me when is the best situation to use Module or Class.
I have no idea when should I use module or class, because no matter i use
module or class, i always could get the results that are what i want. but
just the declare and calling method is a bit different.
Regards
Chong
Nov 21 '05
16  10994 
Very loosely speaking:
Anything that requires more than one instance - think Class.
If you want to share a set of functions/subs and properties use a module -
so long as you don't require multiple instances of the same thing (or object).
OO purists will always say (perhaps) think Class.
You should read up on Classes and OOP though.
"A_PK" wrote: Hi,
I am a VB.net beginner, I do not know what are the major difference between
Module vs Class.
Could someone guide me when is the best situation to use Module or Class.
I have no idea when should I use module or class, because no matter i use
module or class, i always could get the results that are what i want. but
just the declare and calling method is a bit different.
Regards
Chong
> You should avoid using modules, i think they are there only for compatibility with older versions
of VB.
Then why are there so many Modules in the framework? Examples include...
System.Math
System.IO.File
One should use a module when there is no "object" associated with the
functions you are writing.
Too often people become enamored with "Object Orientated" and forget that
objects are not everything, they are just another tool. And like all tools,
there are times when they should not be used.
Off the top of my head, VB's FileSystemObjec t. You have to create an
instance of the FSO before using it, even though you will never need more
than one FSO. In fact, you could create a hundred of them and they would all
be exactly the same.
I cringe whenever I someone mentions a "singleton" pattern. In all most all
cases, your so-called singleton is really just a global variable that people
pretend is a class.
--
Jonathan Allen
"Abubakar" <Ab******@discu ssions.microsof t.com> wrote in message
news:92******** *************** ***********@mic rosoft.com... Hello,
Module in vb.net has everything of a "shared" nature. Once delared it'll
be there throughout the lifetime and instanciated at the start of the
application. This kindof approach introduces too many global variables,
which is not good and as the program grows you'll have a lot of variabes which
belong to the whole program and you kind of kill the concept of
encapsulation, etc,. Use of classes is however an ideal approach where you
think before daclarating and have association-ship as to what variable
belongs to which class and is there for what purpose. You should avoid
using modules, i think they are there only for compatibility with older versions
of VB.
hope that helps.
Abubakar.
http://joehacker.blogspot.com
"A_PK" wrote:
Hi,
I am a VB.net beginner, I do not know what are the major difference
between Module vs Class.
Could someone guide me when is the best situation to use Module or
Class.
I have no idea when should I use module or class, because no matter i
use module or class, i always could get the results that are what i want.
but just the declare and calling method is a bit different.
Regards
Chong
> And I was saying that also because if you see the internal implementation of the modules in
vb.net ie at the IL level, you'll see that its nothing but a class with
shared fields and methods.
True, but it is easier to say "Math is a Module" than "Math is a class that
isn't really a class because it has no constructors and all its members are
shared".
--
Jonathan Allen
"Abubakar" <Ab******@discu ssions.microsof t.com> wrote in message
news:F6******** *************** ***********@mic rosoft.com... Hello Nak,
object-orientation is the ultimate goal. Look at the design of vb.net as
compared to vb6 and before: "everything inside a class". And I was saying
that also because if you see the internal implementation of the modules in
vb.net ie at the IL level, you'll see that its nothing but a class with
shared fields and methods. You can still go for non-object oriented
approach but changing your approach and thinking in object-oriented ways will
always help you if you havnt done that before.
Hope that helps.
Abubakar.
http://joehacker.blogspot.com
"Nak" wrote:
Hi Abubakar,
Modules are not for legacy compatability. There will allways be the
need for modules, and it's certainly not bad programming practice to
take advantage of them. They are great for storing utility methods or global
constants for example. Some people *like* to use classes with shared
members to achieve the same effect but this is neither here nor there.
They are fit for 2 completely different purposes and shouldn't be
compared as such, Classes are for object orientated approaches, modules
aren't.
Nick.
"Abubakar" <Ab******@discu ssions.microsof t.com> wrote in message
news:92******** *************** ***********@mic rosoft.com... Hello,
Module in vb.net has everything of a "shared" nature. Once delared
it'll be
there throughout the lifetime and instanciated at the start of the
application. This kindof approach introduces too many global
variables, which
is not good and as the program grows you'll have a lot of variabes
which belong to the whole program and you kind of kill the concept of
encapsulation, etc,. Use of classes is however an ideal approach where
you think before daclarating and have association-ship as to what variable
belongs to which class and is there for what purpose. You should avoid
using
modules, i think they are there only for compatibility with older
versions of
VB.
hope that helps.
Abubakar.
http://joehacker.blogspot.com
"A_PK" wrote:
> Hi,
>
> I am a VB.net beginner, I do not know what are the major difference
> between
> Module vs Class.
>
> Could someone guide me when is the best situation to use Module or
Class.>
> I have no idea when should I use module or class, because no matter i
use> module or class, i always could get the results that are what i want.
but> just the declare and calling method is a bit different.
>
> Regards
> Chong
>
>
>
Hi Jonathan,
More than likely you will cringe when you see this reply from me, but it
isn't bad; in context, so there is no need. Anyway... One should use a module when there is no "object" associated with the
functions you are writing.
Exactly, everything has a purpose and there is no right or wrong way
about programming. Some techniques prove much better for certain uses than
OOP does. It all depends on what you are trying to achieve.
Too often people become enamored with "Object Orientated" and forget that
objects are not everything, they are just another tool. And like all
tools,
there are times when they should not be used.
ACK.
Off the top of my head, VB's FileSystemObjec t. You have to create an
instance of the FSO before using it, even though you will never need more
than one FSO. In fact, you could create a hundred of them and they would
all
be exactly the same.
I'm a little OT, but I started using JAVA before I used the beta of
VB.NET and I am rather surprised as to how close the JAVA "run-time" is to
the .NET Framework, the way the class hierarchy is laid out is almost
identical in certain circumstances. I'm sure Microsoft had a lot to say but
it just goes to show how much the CLR is needed! I crated my own file
objects for VB6 that are almost identical to VB.NET, it's weird how an
inferior "desktop" language has come up with far better ideas!
I cringe whenever I someone mentions a "singleton" pattern. In all most
all
cases, your so-called singleton is really just a global variable that
people
pretend is a class.
But even they have their uses. For example, if you are sharing objects
between instances then sometimes a singleton is essential! For example, if
I create a singleton object for my application it would make it much easier
for me to maintain only 1 running instance. This appears to be something
that is really overlooked by people that utilize command line arguments, a
singleton is essential! What's the point in having an MDI application with
multiple instances?
Nick.
My app-o-log-gies, I have just observed that you are not the Jonathan that I
thought you were! So Ignore the first paragraph!
"Nak" <a@a.com> wrote in message
news:eN******** ******@TK2MSFTN GP15.phx.gbl... Hi Jonathan,
More than likely you will cringe when you see this reply from me, but
it isn't bad; in context, so there is no need. Anyway...
One should use a module when there is no "object" associated with the
functions you are writing.
Exactly, everything has a purpose and there is no right or wrong way
about programming. Some techniques prove much better for certain uses
than OOP does. It all depends on what you are trying to achieve.
Too often people become enamored with "Object Orientated" and forget that
objects are not everything, they are just another tool. And like all
tools,
there are times when they should not be used.
ACK.
Off the top of my head, VB's FileSystemObjec t. You have to create an
instance of the FSO before using it, even though you will never need more
than one FSO. In fact, you could create a hundred of them and they would
all
be exactly the same.
I'm a little OT, but I started using JAVA before I used the beta of
VB.NET and I am rather surprised as to how close the JAVA "run-time" is to
the .NET Framework, the way the class hierarchy is laid out is almost
identical in certain circumstances. I'm sure Microsoft had a lot to say
but it just goes to show how much the CLR is needed! I crated my own file
objects for VB6 that are almost identical to VB.NET, it's weird how an
inferior "desktop" language has come up with far better ideas!
I cringe whenever I someone mentions a "singleton" pattern. In all most
all
cases, your so-called singleton is really just a global variable that
people
pretend is a class.
But even they have their uses. For example, if you are sharing objects
between instances then sometimes a singleton is essential! For example,
if I create a singleton object for my application it would make it much
easier for me to maintain only 1 running instance. This appears to be
something that is really overlooked by people that utilize command line
arguments, a singleton is essential! What's the point in having an MDI
application with multiple instances?
Nick.
> But even they have their uses. For example, if you are sharing
objects between instances then sometimes a singleton is essential!
Well, there are cases when you want a pointer to either "this single
instance" or "that single instance". For example, different engineer for
calculating geographical distance. (Geo-distance is a lot harder than one
might suppose.)
For example, if
I create a singleton object for my application it would make it much
easier for me to maintain only 1 running instance.
Bad example. Each instance of the application would have an instance of the
singleton.
This appears to be something
that is really overlooked by people that utilize command line arguments, a
singleton is essential!
I've never used one, I just use a module.
What's the point in having an MDI application with
multiple instances?
True.But if for some reason you later decide you really do want multiple
instances of the main window, you'll be glad you didn't use the singleton's
global.
*************** **
Accidental Classes OR How I just screwed up.
If you find that your class has this pattern, you screwed up...
1. There is a shared array.
2. All created objects are stored in the array.
3. There are lots of shared methods that work on said array.
I didn't notice at the time, but I had a collection class hidden within my
shared fields/methods. Now that I need two instances of that collection, I
am [insert explicative here].
In this instance, I should have used a real singleton in order to allow me
more flexibility over the long run.
--
Jonathan Allen
"Nak" <a@a.com> wrote in message
news:eN******** ******@TK2MSFTN GP15.phx.gbl... Hi Jonathan,
More than likely you will cringe when you see this reply from me, but
it isn't bad; in context, so there is no need. Anyway...
One should use a module when there is no "object" associated with the
functions you are writing.
Exactly, everything has a purpose and there is no right or wrong way
about programming. Some techniques prove much better for certain uses
than OOP does. It all depends on what you are trying to achieve.
Too often people become enamored with "Object Orientated" and forget
that objects are not everything, they are just another tool. And like all
tools,
there are times when they should not be used.
ACK.
Off the top of my head, VB's FileSystemObjec t. You have to create an
instance of the FSO before using it, even though you will never need
more than one FSO. In fact, you could create a hundred of them and they would
all
be exactly the same.
I'm a little OT, but I started using JAVA before I used the beta of
VB.NET and I am rather surprised as to how close the JAVA "run-time" is to
the .NET Framework, the way the class hierarchy is laid out is almost
identical in certain circumstances. I'm sure Microsoft had a lot to say
but it just goes to show how much the CLR is needed! I crated my own file
objects for VB6 that are almost identical to VB.NET, it's weird how an
inferior "desktop" language has come up with far better ideas!
I cringe whenever I someone mentions a "singleton" pattern. In all most
all
cases, your so-called singleton is really just a global variable that
people
pretend is a class.
But even they have their uses. For example, if you are sharing
objects between instances then sometimes a singleton is essential! For example,
if I create a singleton object for my application it would make it much
easier for me to maintain only 1 running instance. This appears to be something
that is really overlooked by people that utilize command line arguments, a
singleton is essential! What's the point in having an MDI application
with multiple instances?
Nick.
Hi Jonathan, Bad example. Each instance of the application would have an instance of
the
singleton.
As far as I am aware there is more than one type of singleton. If you
implement a singleton object that uses remoting then you have the perfect
solution, I've been using it now for quite a while and I haven't actually
used anything that's been more reliable or easy to implement. That's after
I got past the initial confusion of remoting.
I've never used one, I just use a module.
They are worth looking into, imagine multiple instances of Adobe
Photoshop, 1 is enough for me that's for sure. But having that quick link
between your instances is great, it saves allot of time and stops you having
to mess around with window messaging and the like.
True.But if for some reason you later decide you really do want multiple
instances of the main window, you'll be glad you didn't use the
singleton's
global.
Well that's where a singleton's flexibility comes in, I'm sure it
wouldn't be difficult to set a maximum number of instances, and when you
launch 1 after the limit has been met; to have the choice of which instance
to send the arguments too.
Accidental Classes OR How I just screwed up.
If you find that your class has this pattern, you screwed up...
1. There is a shared array.
2. All created objects are stored in the array.
3. There are lots of shared methods that work on said array.
I didn't notice at the time, but I had a collection class hidden within my
shared fields/methods. Now that I need two instances of that collection, I
am [insert explicative here].
In this instance, I should have used a real singleton in order to allow me
more flexibility over the long run.
I'm obviously no master of singleton implementation, most of the
information that I found about it was written by an MVP in here, though I
can't remember the exact person, may have been Jay. Anyway, I think the
phrase is "6ugger"! http://www.codeproject.com/dotnet/remotingsingleton.asp
^Check that out :-) With a remoting singleton you could even maintain 1
instance across a network, though I'm sure it wouldn't be without it's
difficulties!
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