SysUtils.LoadPackage replaces Aplication.OnMessage handler
I have a main form where I set a handler for the Application.OnMessage event. (Code of this handler is placed in the main form). Then, while running the program, there can be calls to SysUtils.LoadPackage that loads some bpl-package. And after that is loaded, the handler of Application.OnMessage is changed.
I couldn't find what doing this. At least there is not right such code that goes Application.OnMessage := in the package.
One more thing: in the debugger, before LoadPackage, I see OnMessage handler described as Main.TMainForm.AppMessage. All other handlers (such as OnMinimize, OnModalBegin e.t.c.) are nil. And after LoadPackage all events have handlers, described as Vcl.AppEvnts.TMultiCaster.DoMessage.
delphi delphi-10.2-tokyo
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
|
show 7 more comments
I have a main form where I set a handler for the Application.OnMessage event. (Code of this handler is placed in the main form). Then, while running the program, there can be calls to SysUtils.LoadPackage that loads some bpl-package. And after that is loaded, the handler of Application.OnMessage is changed.
I couldn't find what doing this. At least there is not right such code that goes Application.OnMessage := in the package.
One more thing: in the debugger, before LoadPackage, I see OnMessage handler described as Main.TMainForm.AppMessage. All other handlers (such as OnMinimize, OnModalBegin e.t.c.) are nil. And after LoadPackage all events have handlers, described as Vcl.AppEvnts.TMultiCaster.DoMessage.
delphi delphi-10.2-tokyo
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
2
The package implements its own Application.Onmessage handler perhaps? How can we know without knowing what is in either your application or the bpl.
– Dsm
Nov 12 '18 at 12:09
1
Including unitAppEventswill through unit's initialization create aTMultiCaster, which assigns handlers to (some or all?)TApplicationevents.
– nil
Nov 12 '18 at 12:55
2
Set a breakpoint just after InitControls in vcl.controls.initialization. Run application. When the breakpoint is hit, set a data breakpoint for Application.FOnMessage. Run (resume) again. When the data breakpoint is hit, examine the code.
– Sertac Akyuz
Nov 12 '18 at 13:00
1
That unit contains the TApplicationEvents component, which can be used to assign application events at designtime. Because you could use multiple components, I think the unit attaches its own event handler, which then forwards any events to the event handlers assigned to all the TApplicationEvent components. It would be nice, of course, if it kept track of existing handlers, because if every bpl is going to do the same trick again, that also implies that TApplicationEvents wouldn't work well at all in applications with multiple packages...
– GolezTrol
Nov 12 '18 at 16:01
1
@GolezTrol you are right thatTApplicationEventsis a multicaster, it delegatesTApplicationevents to everyTApplicationEventsinstance, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers toTApplicationdirectly. So yes, the solution to the OP's issue is to addTApplicationEventsto theMainForm.
– Remy Lebeau
Nov 13 '18 at 6:08
|
show 7 more comments
I have a main form where I set a handler for the Application.OnMessage event. (Code of this handler is placed in the main form). Then, while running the program, there can be calls to SysUtils.LoadPackage that loads some bpl-package. And after that is loaded, the handler of Application.OnMessage is changed.
I couldn't find what doing this. At least there is not right such code that goes Application.OnMessage := in the package.
One more thing: in the debugger, before LoadPackage, I see OnMessage handler described as Main.TMainForm.AppMessage. All other handlers (such as OnMinimize, OnModalBegin e.t.c.) are nil. And after LoadPackage all events have handlers, described as Vcl.AppEvnts.TMultiCaster.DoMessage.
delphi delphi-10.2-tokyo
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
I have a main form where I set a handler for the Application.OnMessage event. (Code of this handler is placed in the main form). Then, while running the program, there can be calls to SysUtils.LoadPackage that loads some bpl-package. And after that is loaded, the handler of Application.OnMessage is changed.
I couldn't find what doing this. At least there is not right such code that goes Application.OnMessage := in the package.
One more thing: in the debugger, before LoadPackage, I see OnMessage handler described as Main.TMainForm.AppMessage. All other handlers (such as OnMinimize, OnModalBegin e.t.c.) are nil. And after LoadPackage all events have handlers, described as Vcl.AppEvnts.TMultiCaster.DoMessage.
delphi delphi-10.2-tokyo
delphi delphi-10.2-tokyo
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
edited Nov 12 '18 at 16:17
GolezTrol
97.9k9130174
97.9k9130174
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
asked Nov 12 '18 at 11:57
DaugawpilsDaugawpils
171
171
2
The package implements its own Application.Onmessage handler perhaps? How can we know without knowing what is in either your application or the bpl.
– Dsm
Nov 12 '18 at 12:09
1
Including unitAppEventswill through unit's initialization create aTMultiCaster, which assigns handlers to (some or all?)TApplicationevents.
– nil
Nov 12 '18 at 12:55
2
Set a breakpoint just after InitControls in vcl.controls.initialization. Run application. When the breakpoint is hit, set a data breakpoint for Application.FOnMessage. Run (resume) again. When the data breakpoint is hit, examine the code.
– Sertac Akyuz
Nov 12 '18 at 13:00
1
That unit contains the TApplicationEvents component, which can be used to assign application events at designtime. Because you could use multiple components, I think the unit attaches its own event handler, which then forwards any events to the event handlers assigned to all the TApplicationEvent components. It would be nice, of course, if it kept track of existing handlers, because if every bpl is going to do the same trick again, that also implies that TApplicationEvents wouldn't work well at all in applications with multiple packages...
– GolezTrol
Nov 12 '18 at 16:01
1
@GolezTrol you are right thatTApplicationEventsis a multicaster, it delegatesTApplicationevents to everyTApplicationEventsinstance, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers toTApplicationdirectly. So yes, the solution to the OP's issue is to addTApplicationEventsto theMainForm.
– Remy Lebeau
Nov 13 '18 at 6:08
|
show 7 more comments
2
The package implements its own Application.Onmessage handler perhaps? How can we know without knowing what is in either your application or the bpl.
– Dsm
Nov 12 '18 at 12:09
1
Including unitAppEventswill through unit's initialization create aTMultiCaster, which assigns handlers to (some or all?)TApplicationevents.
– nil
Nov 12 '18 at 12:55
2
Set a breakpoint just after InitControls in vcl.controls.initialization. Run application. When the breakpoint is hit, set a data breakpoint for Application.FOnMessage. Run (resume) again. When the data breakpoint is hit, examine the code.
– Sertac Akyuz
Nov 12 '18 at 13:00
1
That unit contains the TApplicationEvents component, which can be used to assign application events at designtime. Because you could use multiple components, I think the unit attaches its own event handler, which then forwards any events to the event handlers assigned to all the TApplicationEvent components. It would be nice, of course, if it kept track of existing handlers, because if every bpl is going to do the same trick again, that also implies that TApplicationEvents wouldn't work well at all in applications with multiple packages...
– GolezTrol
Nov 12 '18 at 16:01
1
@GolezTrol you are right thatTApplicationEventsis a multicaster, it delegatesTApplicationevents to everyTApplicationEventsinstance, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers toTApplicationdirectly. So yes, the solution to the OP's issue is to addTApplicationEventsto theMainForm.
– Remy Lebeau
Nov 13 '18 at 6:08
2
2
The package implements its own Application.Onmessage handler perhaps? How can we know without knowing what is in either your application or the bpl.
– Dsm
Nov 12 '18 at 12:09
The package implements its own Application.Onmessage handler perhaps? How can we know without knowing what is in either your application or the bpl.
– Dsm
Nov 12 '18 at 12:09
1
1
Including unit
AppEvents will through unit's initialization create a TMultiCaster, which assigns handlers to (some or all?) TApplication events.– nil
Nov 12 '18 at 12:55
Including unit
AppEvents will through unit's initialization create a TMultiCaster, which assigns handlers to (some or all?) TApplication events.– nil
Nov 12 '18 at 12:55
2
2
Set a breakpoint just after InitControls in vcl.controls.initialization. Run application. When the breakpoint is hit, set a data breakpoint for Application.FOnMessage. Run (resume) again. When the data breakpoint is hit, examine the code.
– Sertac Akyuz
Nov 12 '18 at 13:00
Set a breakpoint just after InitControls in vcl.controls.initialization. Run application. When the breakpoint is hit, set a data breakpoint for Application.FOnMessage. Run (resume) again. When the data breakpoint is hit, examine the code.
– Sertac Akyuz
Nov 12 '18 at 13:00
1
1
That unit contains the TApplicationEvents component, which can be used to assign application events at designtime. Because you could use multiple components, I think the unit attaches its own event handler, which then forwards any events to the event handlers assigned to all the TApplicationEvent components. It would be nice, of course, if it kept track of existing handlers, because if every bpl is going to do the same trick again, that also implies that TApplicationEvents wouldn't work well at all in applications with multiple packages...
– GolezTrol
Nov 12 '18 at 16:01
That unit contains the TApplicationEvents component, which can be used to assign application events at designtime. Because you could use multiple components, I think the unit attaches its own event handler, which then forwards any events to the event handlers assigned to all the TApplicationEvent components. It would be nice, of course, if it kept track of existing handlers, because if every bpl is going to do the same trick again, that also implies that TApplicationEvents wouldn't work well at all in applications with multiple packages...
– GolezTrol
Nov 12 '18 at 16:01
1
1
@GolezTrol you are right that
TApplicationEvents is a multicaster, it delegates TApplication events to every TApplicationEvents instance, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly. So yes, the solution to the OP's issue is to add TApplicationEvents to the MainForm.– Remy Lebeau
Nov 13 '18 at 6:08
@GolezTrol you are right that
TApplicationEvents is a multicaster, it delegates TApplication events to every TApplicationEvents instance, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly. So yes, the solution to the OP's issue is to add TApplicationEvents to the MainForm.– Remy Lebeau
Nov 13 '18 at 6:08
|
show 7 more comments
1 Answer
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The package in question uses an internal instance of TApplicationEvents, which is a multicaster that intercepts TApplication events and delegates them to every TApplicationEvents instance in the application, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly.
So, to coexist with the package, the solution is to add a TApplicationEvents to your MainForm and assign a handler to its OnMessage event, instead of assigning a handler to the TApplication.OnMessage event directly.
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
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The package in question uses an internal instance of TApplicationEvents, which is a multicaster that intercepts TApplication events and delegates them to every TApplicationEvents instance in the application, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly.
So, to coexist with the package, the solution is to add a TApplicationEvents to your MainForm and assign a handler to its OnMessage event, instead of assigning a handler to the TApplication.OnMessage event directly.
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
add a comment |
The package in question uses an internal instance of TApplicationEvents, which is a multicaster that intercepts TApplication events and delegates them to every TApplicationEvents instance in the application, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly.
So, to coexist with the package, the solution is to add a TApplicationEvents to your MainForm and assign a handler to its OnMessage event, instead of assigning a handler to the TApplication.OnMessage event directly.
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
add a comment |
The package in question uses an internal instance of TApplicationEvents, which is a multicaster that intercepts TApplication events and delegates them to every TApplicationEvents instance in the application, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly.
So, to coexist with the package, the solution is to add a TApplicationEvents to your MainForm and assign a handler to its OnMessage event, instead of assigning a handler to the TApplication.OnMessage event directly.
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
The package in question uses an internal instance of TApplicationEvents, which is a multicaster that intercepts TApplication events and delegates them to every TApplicationEvents instance in the application, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers to TApplication directly.
So, to coexist with the package, the solution is to add a TApplicationEvents to your MainForm and assign a handler to its OnMessage event, instead of assigning a handler to the TApplication.OnMessage event directly.
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
answered Nov 13 '18 at 6:13
Remy LebeauRemy Lebeau
332k18251443
332k18251443
add a comment |
add a comment |
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2
The package implements its own Application.Onmessage handler perhaps? How can we know without knowing what is in either your application or the bpl.
– Dsm
Nov 12 '18 at 12:09
1
Including unit
AppEventswill through unit's initialization create aTMultiCaster, which assigns handlers to (some or all?)TApplicationevents.– nil
Nov 12 '18 at 12:55
2
Set a breakpoint just after InitControls in vcl.controls.initialization. Run application. When the breakpoint is hit, set a data breakpoint for Application.FOnMessage. Run (resume) again. When the data breakpoint is hit, examine the code.
– Sertac Akyuz
Nov 12 '18 at 13:00
1
That unit contains the TApplicationEvents component, which can be used to assign application events at designtime. Because you could use multiple components, I think the unit attaches its own event handler, which then forwards any events to the event handlers assigned to all the TApplicationEvent components. It would be nice, of course, if it kept track of existing handlers, because if every bpl is going to do the same trick again, that also implies that TApplicationEvents wouldn't work well at all in applications with multiple packages...
– GolezTrol
Nov 12 '18 at 16:01
1
@GolezTrol you are right that
TApplicationEventsis a multicaster, it delegatesTApplicationevents to everyTApplicationEventsinstance, allowing multiple Forms, components, etc to receive the same app events without stepping on each other's toes trying to assign handlers toTApplicationdirectly. So yes, the solution to the OP's issue is to addTApplicationEventsto theMainForm.– Remy Lebeau
Nov 13 '18 at 6:08