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...ignore/hide particular exception?

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This article covers the following:

Ignoring exception means that EurekaLog will act like there was no EurekaLog installed. This means that exception will not be handled by EurekaLog. This usually means that exception will be handled by RTL/VCL, which will show MessageBox for the exception.
Expecting exception means that EurekaLog will process exception, but not create bug report for it. E.g. EurekaLog dialog will be shown, but there will be no details (call stack, etc.), no sending will be performed.
Hiding exception means that exception will be completely hidden, e.g. act like EAbort. This means no dialog will be shown, no exception processing will take place.

 

See also: how to handle an exception?

 


 

Recommended

We recommend to set up exception processing in your own code when possible. For example, if you want to hide an exception:

 

try
  QueryDataView.Active := True;
except
  on E: EEDBException do
  begin

    // Check if this is the exception that you want to hide
    if E.Message = '...' then // only as an example!
      Abort  // Hide this exception
    else
      raise// Process any other exception as usual
  end;
end;

 

or:

 

procedure TForm1.ApplicationEvents1Exception(Sender: TObject; E: Exception);
begin
  // Check if this is the exception that you want to hide
  if E.Message = '...' then // only as an example!
    Exit; // Hide this exception by doing nothing
 
  // Process any other exception as usual
  // If EurekaLog is installed - this code will call EurekaLog
  // See also: How to handle an exception?
  Application.ShowException(E);
end;

 

 

That way - your application will behave the same way with and without EurekaLog.

 


 

Not recommended

Use EurekaLog's customization features only when you can't modify your own code (for example, exception happens in 3rd party code outside of your control).

 

Step 1: Identify the exception

First, you have to identify exception which you want to ignore. You can identify exception by:

Exception class name;
Exception module;
Exception location:
oRoutine;
oLine;
oAddress or offset;
Exception message;
Exception thread;
Other information.

 

It is best to check/specify as much information as you can. Otherwise you may ignore/hide wrong exceptions as well.

 

Step 2: Alter the behavior

Once the exception is identified - you can instruct EurekaLog to ignore this exception. You can:

Instruct EurekaLog to ignore this exception. Exception will be handled by RTL/VCL, as if EurekaLog was not installed. Typically this means showing MessageBox for the exception;
Instruct EurekaLog to consider this exception to be an expected exception. EurekaLog will handle the exception, but not show details, just the message. This means showing EurekaLog dialog for the exception, but no bug report will be created/send. See also for more details.
Instruct EurekaLog to "eat" (e.g. hide) exception. Exception will not be handled/processed at all, it will "disappear". E.g. exception will act like EAbort.

 

Note: you may want to mark exception as expected instead of ignoring it.

 

See also:

 


 

There are several available methods. Not all methods supports all of the features discussed above. This article covers the following options:

1. Use custom attributes
2. Use filters
3. Use event handlers
4. Use code to explicitly ignore exception

 

 

Option 1

Use custom attributes:

 

1. Ignore the exception:

 

uses
  EClasses,
  ETypes;
 
type
  [EurekaLogHandler(fhtRTL)]
  ETestException = class(Exception);
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  // ETestException will be ignored by EurekaLog and
  // it always will be handled by your application
  // (as if EurekaLog would be disabled).
  // In other words, this will be catched by standard
  // Application.HandleException method.
  // A default MessageBox will be shown.
  raise ETestException.Create('Error Message');
end;

 

2. Expect the exception:

 

uses
  EClasses;
 
type
  [EurekaLogExpected()]
  ETestException = class(Exception);
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  // ETestException will be handled by EurekaLog.
  // However, it would be considered as "expected".
  // In other words, this will be catched and shown by EurekaLog.
  // But (EurekaLog) error dialog will lack
  // "details", "send" and "restart" options.

  // No bug report will be created.
  raise ETestException.Create('Error Message');
end;

 

3. Hide the exception:

 

uses
  EClasses;
 
type
  [EurekaLogHandler(fhtNone)]
  ETestException = class(Exception);
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  // ETestException will be handled by EurekaLog.
  // However, it would be completely hidden.
  // No dialog, no bug report, no sending.
  // Exception will act like EAbort.
  raise ETestException.Create('Error Message');
end;

 

Read more about this method.

 

 

Option 2

Use exception filters. Typically, you create exception filters at design-time:

 

 

Ignoring ETestException exception

(by using "RTL" handler)

 

Use "Set Handler to RTL" to ignore the exception;
Use "Set Handler to EurekaLog" + set "Expected Exception Context ID = -1" to expect the exception;
Use "Set Handler to (None)" to hide the exception.

 

You can also create exception filters manually from code:

 

1. Ignore the exception:

 

uses
  EModules;
 
  CurrentEurekaLogOptions.ExceptionsFilters.AddIgnoredException(ETestException);
 
  // ETestException will be ignored by EurekaLog and
  // it always will be handled by your application
  // (as if EurekaLog would be disabled).
  raise ETestException.Create('Error Message');

 

2. Expect the exception:

 

uses
  EModules;
 
  CurrentEurekaLogOptions.ExceptionsFilters.AddExpectedException(ETestException);
 
  // ETestException will be handled by EurekaLog.
  // However, it would be considered as expected.
  // "details", "send" and "restart" options will not be shown.
  raise ETestException.Create('Error Message');

 

3. Hide the exception:

 

uses
  EModules;
 
  CurrentEurekaLogOptions.ExceptionsFilters.AddFullyIgnoredException(ETestException);
 
  // ETestException will be handled by EurekaLog.
  // However, it would be completely hidden.
  // No dialog, no bug report, no sending.
  // Exception will act like EAbort.
  raise ETestException.Create('Error Message');

 

4. Fully customizable filter from code:

 

uses
  EModules,
  ETypes;
 
// Create custom filter:
var
  Filter: TEurekaExceptionFilter;
begin
  FillChar(Filter, SizeOf(Filter), 0);
 
  Filter.Active := True;
  Filter.ExceptionClassName := ETestException.ClassName;
  Filter.ExceptionType := fetAll;
  Filter.DialogType := edtUnchanged;
  Filter.HandlerType := fhtRTL;
  Filter.ActionType := fatUnchanged;
 
  CurrentEurekaLogOptions.ExceptionsFilters.Add(Filter);
 
  // ETestException will be ignored by EurekaLog and
  // it always will be handled by your application
  // (as if EurekaLog would be disabled).
  raise ETestException.Create('Error Message');
end;

 

Read more about this method here.

 

 

Option 3

Use event handlers.

 

1. Ignore the exception:

 

uses
  EEvents; // for RegisterEventExceptionNotify
 
type
  ETestException = class(Exception);
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  // ETestException will be ignored by EurekaLog and
  // it always will be handled by your application
  // (as if EurekaLog would be disabled).
  raise ETestException.Create('Error Message');
end;
 
procedure IgnoreException(const ACustom: Pointer; 

  AExceptionInfo: TEurekaExceptionInfo; 

  var AHandle: Boolean; 

  var ACallNextHandler: Boolean);
begin
  // Specify EurekaLog to ignore ETestException

  
  if // this check matches ETestException only, but skips child classes

     AExceptionInfo.ExceptionClass = ETestException.ClassName then 
  begin

    // Do not call EurekaLog for this exception, 

    // e.g. exception will be processed by RTL/VCL
    AHandle := False;

    // No need to call any other event handlers (if any assigned)
    ACallNextHandler := False;
    Exit;
  end;
end;
 
initialization
  RegisterEventExceptionNotify(nil, IgnoreException);
end.

 

2. Expect the exception:

 

uses
  EEvents; // for RegisterEventExceptionNotify
 
type
  ETestException = class(Exception);
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  // ETestException will be handled by EurekaLog.
  // However, it would be considered as expected.
  // "details", "send" and "restart" options will not be shown.
  raise ETestException.Create('Error Message');
end;
 
procedure ExpectException(const ACustom: Pointer; 

  AExceptionInfo: TEurekaExceptionInfo; 

  var AHandle: Boolean; 

  var ACallNextHandler: Boolean);
begin
  // Mark exception as expected, but allow it to be handled by EurekaLog.
  if (AExceptionInfo.ExceptionObject <> niland
     (AExceptionInfo.ExceptionNative) and

     // this check matches ETestException and any of its child classes
     (Exception(AExceptionInfo.ExceptionObject).InheritsFrom(ETestException)) and 
     (AExceptionInfo.ExceptionMessage = 'Error Message'then
  begin

    // Indicate that exception is expected
    AExceptionInfo.ExpectedContext := -1;

    // Don't change any other options, 

    // e.g. exception will be processed by EurekaLog
    Exit;
  end;
end;
 
initialization
  RegisterEventExceptionNotify(nil, ExpectException);
end.

 

3. Hide the exception:

 

uses
  EEvents; // for RegisterEventExceptionNotify
 
type
  ETestException = class(Exception);
 
procedure TForm1.Button1Click(Sender: TObject);
begin
  // ETestException will be handled by EurekaLog.
  // However, it would be completely hidden.
  // No dialog, no bug report, no sending.
  // Exception will act like EAbort.
  raise ETestException.Create('Error Message');
end;
 
procedure HideException(const ACustom: Pointer; 

  AExceptionInfo: TEurekaExceptionInfo; 

  var AHandle: Boolean; 

  var ACallNextHandler: Boolean);
begin
  // "Eat" the exception
  if AExceptionInfo.ExceptionMessage = 'Error Message' then
  begin

    // Indicate that the exception should be handled by EurekaLog, not VCL
    AHandle := True;
    // Indicate that the exception was already processed/handled, 

    // e.g. EurekaLog should do nothing
    AExceptionInfo.Handled := True;
    // No need to call any other event handlers
    ACallNextHandler := False;
    Exit;
  end;
end;
 
initialization
  RegisterEventExceptionNotify(nil, HideException);
end.

 

4. Here is an example of how you can check various properties of your exception (we recommend to specify as much as you can):

 

procedure ExceptionNotify(const ACustom: Pointer; 

  AExceptionInfo: TEurekaExceptionInfo; 

  var AHandle: Boolean; 

  var ACallNextHandler: Boolean);
begin

  if // check exception class name
     (AExceptionInfo.ExceptionClass = 'EOSError'and 

     // check exception message
     (AExceptionInfo.ExceptionMessage = 'Access Denied'and 

     // check that there is exception object

     (AExceptionInfo.ExceptionObject <> niland 

     // check that it is a Delphi/Builder object
     (AExceptionInfo.ExceptionNative) and 

     // check exception class 

     // (only for .ExceptionNative = True and .ExceptionObject <> nil)
     (Exception(AExceptionInfo.ExceptionObject).InheritsFrom(EOSError)) and 

     // check any additional exception properties
     (EOSError(AExceptionInfo.ExceptionObject).ErrorCode = ERROR_ACCESS_DENIED) and 

     // check call stack
     (AExceptionInfo.CallStack.Count > 0) and 
     (AExceptionInfo.CallStack[0].Location.UnitName = 'ServiceProvider'and
     (AExceptionInfo.CallStack[0].Location.ProcedureName = 'Connect'and

     // check exception address
     (AExceptionInfo.Address = Pointer($00456789)) and 

     // check exception module
     (AExceptionInfo.Module = $00400000) and 

     (AExceptionInfo.Module = HInstance) and 

     // check exception module name
     SameFileName(ExtractFileName(AExceptionInfo.ModuleName), 'Project1.exe'and 

     // check exception thread
     (AExceptionInfo.ThreadID = MainThreadID) and 

     // check for known BugID
     (AExceptionInfo.BugID = $E36F0000) and 

     // check for handler (what hook has catched the exception)
     (AExceptionInfo.Handler = atVCL) and 

     // check for misc. props
     (not AExceptionInfo.Handled) and 
     AExceptionInfo.SafeCallExpt and
     AExceptionInfo.ThreadException
     AExceptionInfo.InitializationException then
  begin
    // ...
    Exit;
  end;
end;

 

Read more about this method here.

 

 

Option 4

Use coding.

 

1. Ignore the exception by disabling EurekaLog for the duration of the exception in question.

 

SetEurekaLogStateInThread(0, False);
try
  SomeStrVar := StrToInt(SomeIntVar);
finally
  SetEurekaLogStateInThread(0, True);
end;

 

2. Expect the exception by marking it:

 

uses 
  EBase; // for RaiseExpected
 
// ...
 
  RaiseExpected(ETestException.Create('Error Message'));

 

or

 

uses 
  EBase; // for MarkExpected
 
// ...
 
try
  SomeStrVar := StrToInt(SomeIntVar);
except
  on E: EConvertError do
  begin
    MarkExpected(E);
    raise;
  end;
end;

 

3. Hide the exception with an explicit try/except block:

 

try
  SomeStrVar := StrToInt(SomeIntVar);
except
  SomeStrVar := -1;
end;

 

 

See also:




Send feedback... Build date: 2021-10-15
Last edited: 2021-06-21
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