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Exception Trapping (Delphi and Corel Paradox Cross Reference Guide)

By Mike Prestwood

Delphi versus Corel Paradox: A side by side comparison between Delphi and Corel Paradox.

Statements

Common statements such as if statements, loops, etc.

Exception Trapping

[Other Languages]

Languages Focus

A common usage of exception handling is to obtain and use resources in a "try-it" block, deal with any exceptions in an "exceptions" block, and release the resources in some kind of "final" block which executes whether or not any exceptions are trapped.

Delphi: try..except, try..finally

Use a try..except..end block to trap and process errors.

Delphi also offers a try...finally where code will execute in the finally section no matter what. It's common to put a try..except inside a try..finally.

Syntax Example:

var
  y : Double;
begin
  try
    y := 0;
    y := (1/y);
    ShowMessage(FloatToStr(y));
  except
    ShowMessage('You cannot divide by zero.');
  end;
end;

Corel Paradox: try...onFail

ObjectPAL has a try...onFail statement but does not have a finally-type component. However, the code afer endTry will execute.

try

onFail

endTry

Syntax Example:

var
  i SmallInt
endVar

try
  i = 0
  i = 1/i
onFail
  msgInfo("", "You cannot divide by zero.")
endTry

Debugging ObjectPAL Code