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Jeff Kish
Guest
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 Posted: Wed Nov 26, 2003 6:27 pm Post subject: deriving from existing components |
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Greetings.
I'm a bit confused here.
I see an example on the borland site (at:
http://community.borland.com/article/0,1410,21743,00.html) that
has a class derived from TListBox (.h file looks like this):
class PACKAGE TActiveListBox : public TListBox
:
:
Now normally if I want to use a TListBox I'll drag it onto my form
and away I go.
If I want to use the above mentioned code, then what are
the mechanics involved? Do I still drag a TListBox onto
a form and name it "TActiveListBox", then include the code
mentioned above?
Thanks
Jeff
Jeff Kish
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Dennis Jones
Guest
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| Posted: Wed Nov 26, 2003 6:37 pm Post subject: Re: deriving from existing components |
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"Jeff Kish" <jeff.kish (AT) mro (DOT) com> wrote
| Quote: | Greetings.
I'm a bit confused here.
I see an example on the borland site (at:
http://community.borland.com/article/0,1410,21743,00.html) that
has a class derived from TListBox (.h file looks like this):
class PACKAGE TActiveListBox : public TListBox
:
:
Now normally if I want to use a TListBox I'll drag it onto my form
and away I go.
If I want to use the above mentioned code, then what are
the mechanics involved? Do I still drag a TListBox onto
a form and name it "TActiveListBox", then include the code
mentioned above?
|
If you do not have TActiveListBox installed as a component, BCB will not let
you change a TListBox's type into a TActiveListBox because the
TActiveListBox class must be known to BCB in order for it to exist on the
form at design-time. If the component *is* installed, then you can modify
the .cpp, .h, and .dfm files manually (outside the IDE -- in notepad, for
example) and change every instance of TListBox to TActiveListBox and reload
the project.
If you do not indend to compile the new component into a package and put it
on the component palette, your only option is to create the component at
runtime with, "new TActiveListBox".
- Dennis
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Jeff Kish
Guest
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| Posted: Wed Nov 26, 2003 7:09 pm Post subject: Re: deriving from existing components |
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On Wed, 26 Nov 2003 10:37:43 -0800, "Dennis Jones" <djones (AT) nospam (DOT) com>
wrote:
| Quote: |
snip
If you do not indend to compile the new component into a package and put it
on the component palette, your only option is to create the component at
runtime with, "new TActiveListBox".
- Dennis
So I either create a component and install it, or do it at run time? |
If I create it at run time, then how would I "link" it to a listbox on
my form?
Thanks,
Jeff Kish
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Remy Lebeau (TeamB)
Guest
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| Posted: Wed Nov 26, 2003 9:10 pm Post subject: Re: deriving from existing components |
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"Jeff Kish" <jeff.kish (AT) mro (DOT) com> wrote
| Quote: | If I want to use the above mentioned code, then what
are the mechanics involved?
|
In order to use the component at design-time, you need to put it into a
runtime package and then create a designtime package for registering the
component onto the Component Palette. Then you can use it like any other
component. Please have a look at the help files, there are sections on
writing and instaling custom components.
| Quote: | Do I still drag a TListBox onto a form and name it "TActiveListBox",
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No. When everything is done, you would drag a TActiveListBox instead.
Gambit
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Remy Lebeau (TeamB)
Guest
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| Posted: Wed Nov 26, 2003 9:11 pm Post subject: Re: deriving from existing components |
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"Jeff Kish" <jeff.kish (AT) mro (DOT) com> wrote
| Quote: | If I create it at run time, then how would I "link" it to a
listbox on my form?
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You don't. It *is* the ListBox. You would have to use the new class as a
replacement for the TListBox, not as a companion to it.
Gambit
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Jeff Kish
Guest
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| Posted: Fri Nov 28, 2003 1:45 am Post subject: Re: deriving from existing components |
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On Wed, 26 Nov 2003 13:10:29 -0800, "Remy Lebeau (TeamB)"
<gambit47.no.spam (AT) no (DOT) spam.yahoo.com> wrote:
| Quote: |
"Jeff Kish" <jeff.kish (AT) mro (DOT) com> wrote in message
news:7vr9svsfrs0l58clasitopaiunrttsf71l (AT) 4ax (DOT) com...
If I want to use the above mentioned code, then what
are the mechanics involved?
In order to use the component at design-time, you need to put it into a
runtime package and then create a designtime package for registering the
component onto the Component Palette. Then you can use it like any other
component. Please have a look at the help files, there are sections on
writing and instaling custom components.
Do I still drag a TListBox onto a form and name it "TActiveListBox",
No. When everything is done, you would drag a TActiveListBox instead.
Gambit
Thanks Gambit. So would you say that writing the component and |
installing it is the best way to go here?
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Remy Lebeau (TeamB)
Guest
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| Posted: Fri Nov 28, 2003 6:11 am Post subject: Re: deriving from existing components |
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"Jeff Kish" <kishjjrjj (AT) provide (DOT) net> wrote
| Quote: | So would you say that writing the component
and installing it is the best way to go here?
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It is for you to decide what is best for your own needs. Whether you
install the component on the Palette or instantiate it dynamically at
runtime, either way is going to involve some work on your part. The main
difference is that one allow for setups at design-time while the other is
for setups at runtime.
Gambit
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