Error handlers

Green Tea provide 2 ways to handle error:

error_handler_function

try…catch…finally structures

defcat…deffin (default catch)

error_handler_function

You could declare this function to handle how to show when unhamdled error happened

@error_handler_function($errno,
$errstr, $errfile, $errline)


//do
somethings

errno

The first parameter, errno, will be passed the level of the error raised, as an integer.

errstr

The second parameter, errstr, will be passed the error message, as a string.

errfile

If the callback accepts a third parameter, errfile, it will be passed the filename that the error was raised in, as a string.

errline

If the callback accepts a fourth parameter, errline, it will be passed the line number where the error was raised, as an integer.

errcontext

If the callback accepts a fifth parameter, errcontext, it will be passed an array that points to the active symbol table at the point the error occurred. In other words, errcontext will contain an array of every variable that existed in the scope the error was triggered in. User error handlers must not modify the error context.

try…catch…finally structures

Used to catch possible exception in try block. If a Exception match multiple catches, only the 1^st catch block matched will run. Finally block run whenever any Exception is catch or not.

Ex: If ^DevidedByZeroException happened ($num2=0), catch block 1 will be triggered). If other exception happened, catch block 2 will run. Finally block run whenever any Exception is catch or not.

@devide $num1 $num2

try

$result = $num1 / $num2

catch ^DevidedByZeroException

// catch block 1

@echo “devided by zero”

$result = false

catch ^Exception

// catch block 2

@cho “other exception”

$result = false

finally

return $result

defcat…deffin structures

You could use defcat as default catch for functions, which will catch Exceptions when running current function

defcat and deffin should be at the end of function

@devide $num1 $num2

$result = $num1 / $num2

defcat

^DevidedByZeroException

// catch block 1

@echo “devided by zero”

$result = false

^Exception

// catch block 2

@cho “other exception”

$result = false

deffin

return $result

You could use defcat and deffin outside of functions, which will handle exception for the whole program. They should be at the end of source files.