Exceptions:

Sometimes, parts of a program will fail, and the failure point is not always easy to predict. Paisley handles this with exceptions. To raise an exception, use the error statement along with any message, and an optional as <exception_type> at the end. See the following example:

function this_errors
    error "your error message"
end

try
    call this_errors
catch exception as ex
    # Caught error will land here
    print "Exception caught: {json_encode(ex)}"
end

The output variable (in this case ex) will always be an object that looks like the following:

{
    "message": "your error message",
    "line": 6,
    "stack": [2, 6],
    "type": "exception_type",
}

Where line is the line where the exception was caught, and stack is the line numbers for the function call stack.

Throwing exceptions

To throw an exception, use one of following syntaxes:

error "Some error message" as exception_type
error "Some error message"

The latter is the same as error "Some error message" as exception.

The exception type can be anything; it’s basically just a flag for later catching.

Catching exceptions

The basic syntax for catching errors is:

try
    # Some code here
catch exception_type as variable
    # Handle the error
end

However,

• There can be any number of catch blocks.
• Each catch block can catch any number of exception types.
• The captured variable is optional, and may be excluded.

So the following is totally valid:

try
    # Some code here
catch exception math_error network_error
    # Ignore these
catch invalid_os_error as err
    print "Exception caught: {err.json_encode()}"
end

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