HTML::Mason::Exceptions - Exception objects thrown by Mason
use HTML::Mason::Exceptions ( abbr => [ qw(system_error) ] ); open FH, 'foo' or system_error "cannot open foo: $!";
This module creates the hierarchy of exception objects used by Mason,
and provides some extra methods for them beyond those provided by
Exception::Class
When this module is imported, it is possible to specify a list of
abbreviated function names that you want to use to throw exceptions.
In the SYNOPSIS example, we use the system_error
function to throw a HTML::Mason::Exception::System exception.
These abbreviated functions do not allow you to set additional fields in the exception, only the message.
This is the parent class for all exceptions thrown by Mason. Mason sometimes throws exceptions in this class when we could not find a better category for the message.
Abbreviated as error
The $m->abort method was called.
Exceptions in this class contain the field aborted_value.
The $m->decline method was called.
Exceptions in this class contain the field declined_value.
An exception occurred when attempting to eval an existing object
file.
Exceptions in this class have the field filename, which indicates
what file contained the code that caused the error.
Abbreviated as compilation_error.
The compiler threw an exception because it received incorrect input. For example, this would be thrown if the lexer told the compiler to initialize compilation while it was in the middle of compiling another component.
Abbreviated as compiler_error.
A component was compiled by a compiler or lexer with incompatible options. This is used to tell Mason to recompile a component.
Abbreviated as wrong_compiler_error.
Invalid parameters were passed to a method or function.
Abbreviated as param_error.
This exception indicates that a component contained invalid syntax.
Exceptions in this class have the fields source_line, which is the
actual source where the error was found, comp_name, and
line_number.
Abbreviated as syntax_error.
A system call of some sort, such as a file open, failed.
Abbreviated as system_error.
The requested top level component could not be found.
Abbreviated as top_level_not_found_error.
Some piece of code attempted to call a virtual method which was not overridden.
Abbreviated as virtual_error
Some of the exceptions mentioned above have additional fields, which
are available via accessors. For example, to get the line number of
an HTML::Mason::Exception::Syntax exception, you call the
line_number method on the exception object.
All of the Mason exceptions implement the following methods:
Each of these methods corresponds to a valid error_format parameter
for the Request object such as text or
html.
You can create your own method in the HTML::Mason::Exception
namespace, such as as_you_wish, in which case you could set this
parameter to "you_wish". This method will receive a single argument,
the exception object, and is expected to return some sort of string
containing the formatted error message.
This module also exports the isa_mason_exception function. This
function takes the exception object and an optional string parameter
indicating what subclass to check for.
So it can be called either as:
if ( isa_mason_exception($@) ) { ... }
or
if ( isa_mason_exception($@, 'Syntax') ) { ... }
Note that when specifying a subclass you should not include the leading "HTML::Mason::Exception::" portion of the class name.