Error Class

An Error object encapsulates information about errors -- these may have happened due to scripting errors, or to a communications failure or a failure due to a system call etc.

An Error has various properties -- the three most important of these are:

`class`	Integer	the class of error
`code`	Integer	the code of an error -- this has meaning within the particular error class
`text`	String	a textual description for an error

All error handling within Carapace script is done using the following three functions:

`try`	show the intention to catch errors generated by the supplied expression
`catch`	catch a given class of errors
`throw`	throw an error - so it can be caught elsewhere

This page deals with the Error object which is thrown around.

Error Codes

For a description of the various error classes and their codes, click here

Error Creation

The create function is used to create an Error of a given class etc.

    (create Error 1 2 "ooops!")

creates an error of class 1, code 2 with a (not very helpful) textual description of ooops!.

Other optional arguments can follow the text -- these can be of type Integer, Real or further Strings. The Error object concatenates these into the error text.

Error Properties

property name	property type	description
`class`	Integer	the class of error
`code`	Integer	the code of an error -- this has meaning within the particular error class
`text`	String	a textual description for an error
`file`	String	name of file where the error occurred
`line`	Integer	the line number of the file where the error occurred
`positionInLine`	Integer	the position within the line where the error occurred
`showLocation`	Object	flag to determine whether the `string` method will contain the error location information -- this is a property shared by all instances of an `Error` object

Error Methods

method name	description
`clear`	clear out information within the `Error` object
`set`	set the class, code and text for the `Error`
`locate`	set the file and line location for the `Error`
`exists`	test if an error exists ie. if the `class` is non-zero
`string`	convert the `Error` to a string representation

`clear`

Clear out information within the Error object.

Arguments: none

Return type: the empty List ()

`set`

Set the class, code and text for the Error. Other optional arguments can follow the text -- these can be of type Integer, Real or further Strings. The Error object concatenates these into the error text.

Arguments:

class	`Integer`
code	`Integer`
text	`String`
...	`Integer`, `Real`, or `String`

Return type: the empty List ()

`locate`

Set the file and line location for the Error.

Arguments:

file	`String`
line	`Integer`

Return type: List

`exists`

Test if an error exists ie. if the class is non-zero.

Arguments: none

Return type: List

`string`

Convert the Error to a string representation.

Arguments: none

Return type: String

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