VBA, Using class modules in a code library

Using class modules in a code library

Author	Message
Joel Reinfor #1 / 8	Using class modules in a code library I am attempting to move a class module from the application database file into a code library (mda) file. At first I couldn't see the class module from the application file but I solved that one with some help from Steve Arbaugh's site at http://www.--*.com/ However, I still can't use the class in the application file. When I try to instantiate the class, I get an "Invalid use of New Keyword" error. Any suggestions from anyone? Joel Reinford
Mon, 07 Jun 2004 02:41:06 GMT

Brendan Reynold #2 / 8	Using class modules in a code library There are other ways, but my own preference is to include in the code library a function that returns an instance of the class: Public Function GetFoo() As Foo Dim f As Foo Set f = New Foo Set GetFoo = f Set f = Nothing End Function -- Brendan Reynolds Quote: > I am attempting to move a class module from the application database file > into a code library (mda) file. At first I couldn't see the class module > from the application file but I solved that one with some help from Steve > Arbaugh's site at http://ourworld.compuserve.com/homepages/attac-cg/. > However, I still can't use the class in the application file. When I try to > instantiate the class, I get an "Invalid use of New Keyword" error. Any > suggestions from anyone? > Joel Reinford
Mon, 07 Jun 2004 05:38:44 GMT

Sandra Daigl #3 / 8	Using class modules in a code library This is a limitation of VBA - you can not create a PublicCreatable class. No problem - just create a "helper" function in a standard module in the library db that returns a new instance of your class. For a class named Dog. Public Function NewDog() as Dog NewDog=new dog end function Often, I will also build in the parameters to set up the new instance of the class and do it all from the helper function. -- Sandra Daigle, Microsoft Access MVP Quote: > I am attempting to move a class module from the application database file > into a code library (mda) file. At first I couldn't see the class module > from the application file but I solved that one with some help from Steve > Arbaugh's site at http://ourworld.compuserve.com/homepages/attac-cg/. Quote: > However, I still can't use the class in the application file. When I try to > instantiate the class, I get an "Invalid use of New Keyword" error. Any > suggestions from anyone? > Joel Reinford
Mon, 07 Jun 2004 05:42:17 GMT

Sandra Daigl #4 / 8	Using class modules in a code library Of course I meant to say . . . left off the "Set" ;-) Public Function NewDog() as Dog set NewDog=new dog end function -- Sandra Daigle, Microsoft Access MVP Quote: > This is a limitation of VBA - you can not create a PublicCreatable > class. No problem - just create a "helper" function in a standard > module in the library db that returns a new instance of your class. > For a class named Dog. > Public Function NewDog() as Dog > NewDog=new dog > end function > Often, I will also build in the parameters to set up the new instance > of the class and do it all from the helper function. > -- > Sandra Daigle, Microsoft Access MVP > > I am attempting to move a class module from the application database > file > > into a code library (mda) file. At first I couldn't see the class > module > > from the application file but I solved that one with some help from > Steve > > Arbaugh's site at > http://ourworld.compuserve.com/homepages/attac-cg/. > > However, I still can't use the class in the application file. When I > try to > > instantiate the class, I get an "Invalid use of New Keyword" error. > Any > > suggestions from anyone? > > Joel Reinford
Mon, 07 Jun 2004 05:53:16 GMT

Stephen Leban #5 / 8	Using class modules in a code library Hi Brendan, GetFoo is available to be used as a var of the type as it is declared in the function. So all you would need is: Public Function GetFoo() As Foo Set GetFoo = New Foo End Function Just my $.02 worth. HTH Stephen Lebans http://www.lebans.com Access Code, Tips and Tricks Please respond only to the newsgroups so everyone can benefit. Quote: > There are other ways, but my own preference is to include in the code > library a function that returns an instance of the class: > Public Function GetFoo() As Foo > Dim f As Foo > Set f = New Foo > Set GetFoo = f > Set f = Nothing > End Function > -- > Brendan Reynolds > > I am attempting to move a class module from the application database file > > into a code library (mda) file. At first I couldn't see the class module > > from the application file but I solved that one with some help from Steve > > Arbaugh's site at http://ourworld.compuserve.com/homepages/attac-cg/. - Hide quoted text - - Show quoted text - Quote: > > However, I still can't use the class in the application file. When I try > to > > instantiate the class, I get an "Invalid use of New Keyword" error. Any > > suggestions from anyone? > > Joel Reinford
Mon, 07 Jun 2004 09:26:46 GMT

Brendan Reynold #6 / 8	Using class modules in a code library Yes, I've got into the habit of avoiding "= New", but I have to admit that in this particular situation, I can't actually think of any real justification for avoiding it! :-) Most of my functions of this type tend to be a little more complex than this example, though. I use optional arguments to the function to set properties of the object, so that in the calling code I can create an instance of the object and set the properties in one line of code: Public Function GetFoo(Optional ByVal Arg1 As String, Optional ByVal Arg2 As String) As Foo Dim f As Foo Set f = New Foo With f .Prop1 = Arg1 .Prop2 = Arg2 End With Set GetFoo = f Set f = Nothing End Function -- Brendan Reynolds Quote: > Hi Brendan, > GetFoo is available to be used as a var of the type as it is declared in > the function. > So all you would need is: > Public Function GetFoo() As Foo > Set GetFoo = New Foo > End Function > Just my $.02 worth. > HTH > Stephen Lebans > http://www.lebans.com > Access Code, Tips and Tricks > Please respond only to the newsgroups so everyone can benefit. > > There are other ways, but my own preference is to include in the code > > library a function that returns an instance of the class: > > Public Function GetFoo() As Foo > > Dim f As Foo > > Set f = New Foo > > Set GetFoo = f > > Set f = Nothing > > End Function > > -- > > Brendan Reynolds > > > I am attempting to move a class module from the application database > file > > > into a code library (mda) file. At first I couldn't see the class > module > > > from the application file but I solved that one with some help from > Steve > > > Arbaugh's site at > http://ourworld.compuserve.com/homepages/attac-cg/. > > > However, I still can't use the class in the application file. When I > try > > to > > > instantiate the class, I get an "Invalid use of New Keyword" error. > Any > > > suggestions from anyone? > > > Joel Reinford
Mon, 07 Jun 2004 18:42:49 GMT

Joel Reinfor #7 / 8	Using class modules in a code library It seems to me that the helper function method would be messy since you'd be creating an object in both the library code and the callling application without a good way to destroy the object that the library instantiated. Fortunately, I got the answer I like better from Steve Arbaugh. For anyone else who wants to do this, here's how. I'm working in Access 2000 but I believe this answer would apply to 97 and 2002 as well. The way to make this happen is to create a plain text file with these two lines. VB_Creatable = True VB_Exposed = True In the VBE: 1) Insert a new class module 2) From the Insert menu choose File and insert the text file 3) Add the class module code Now the class module can be instantiated directly from the calling application without any helper functions. It seems as though you have to repeat this process each time. For example, I tried to save a "starter" class module that would have these attributes set this way. My idea was that I would do a "Save As" from the Access window so I wouldn't have to keep inserting the text file. However, that didn't work for me. Steve's website got me started in the right direction. It's at http://ourworld.compuserve.com/homepages/attac-cg/ if anyone else would like to see his comments. Best wishes for the holidays! Quote: > This is a limitation of VBA - you can not create a PublicCreatable > class. No problem - just create a "helper" function in a standard > module in the library db that returns a new instance of your class. > For a class named Dog. > Public Function NewDog() as Dog > NewDog=new dog > end function > Often, I will also build in the parameters to set up the new instance > of the class and do it all from the helper function. > -- > Sandra Daigle, Microsoft Access MVP > > I am attempting to move a class module from the application database > file > > into a code library (mda) file. At first I couldn't see the class > module > > from the application file but I solved that one with some help from > Steve > > Arbaugh's site at > http://ourworld.compuserve.com/homepages/attac-cg/. > > However, I still can't use the class in the application file. When I > try to > > instantiate the class, I get an "Invalid use of New Keyword" error. > Any > > suggestions from anyone? > > Joel Reinford
Wed, 09 Jun 2004 06:18:34 GMT

Brendan Reynold #8 / 8	Using class modules in a code library I'm not criticising Steve's alternative, but if you look at the examples I posted, you'll see that they do destroy the object that was instantiated in the library. -- Brendan Reynolds Quote: > It seems to me that the helper function method would be messy since you'd be > creating an object in both the library code and the callling application > without a good way to destroy the object that the library instantiated. > Fortunately, I got the answer I like better from Steve Arbaugh. For anyone > else who wants to do this, here's how. I'm working in Access 2000 but I > believe this answer would apply to 97 and 2002 as well. > The way to make this happen is to create a plain text file with these two > lines. > VB_Creatable = True > VB_Exposed = True > In the VBE: > 1) Insert a new class module > 2) From the Insert menu choose File and insert the text file > 3) Add the class module code > Now the class module can be instantiated directly from the calling > application without any helper functions. > It seems as though you have to repeat this process each time. For example, I > tried to save a "starter" class module that would have these attributes set > this way. My idea was that I would do a "Save As" from the Access window so > I wouldn't have to keep inserting the text file. However, that didn't work > for me. > Steve's website got me started in the right direction. It's at > http://ourworld.compuserve.com/homepages/attac-cg/ if anyone else would like > to see his comments. > Best wishes for the holidays! > > This is a limitation of VBA - you can not create a PublicCreatable > > class. No problem - just create a "helper" function in a standard > > module in the library db that returns a new instance of your class. > > For a class named Dog. > > Public Function NewDog() as Dog > > NewDog=new dog > > end function > > Often, I will also build in the parameters to set up the new instance > > of the class and do it all from the helper function. > > -- > > Sandra Daigle, Microsoft Access MVP > > > I am attempting to move a class module from the application database > > file > > > into a code library (mda) file. At first I couldn't see the class > > module > > > from the application file but I solved that one with some help from > > Steve > > > Arbaugh's site at > > http://ourworld.compuserve.com/homepages/attac-cg/. > > > However, I still can't use the class in the application file. When I > > try to > > > instantiate the class, I get an "Invalid use of New Keyword" error. > > Any > > > suggestions from anyone? > > > Joel Reinford
Wed, 09 Jun 2004 20:51:43 GMT

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