NAME

       HTML::Mason::Exceptions - Exception objects thrown by Mason

SYNOPSIS

         use HTML::Mason::Exceptions ( abbr => [ qw(system_error) ] );

         open FH, 'foo' or system_error "cannot open foo: $!";

DESCRIPTION

       This module creates the hierarchy of exception objects used by Mason, and provides some extra methods for
       them beyond those provided by "Exception::Class"

IMPORT

       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.

EXCEPTIONS

       HTML::Mason::Exception
           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"

       HTML::Mason::Exception::Abort
           The "$m->abort" method was called.

           Exceptions in this class contain the field "aborted_value".

       HTML::Mason::Exception::Decline
           The "$m->decline" method was called.

           Exceptions in this class contain the field "declined_value".

       HTML::Mason::Exception::Compilation
           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".

       HTML::Mason::Exception::Compiler
           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".

       HTML::Mason::Exception::Compilation::IncompatibleCompiler
           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".

       HTML::Mason::Exception::Params
           Invalid parameters were passed to a method or function.

           Abbreviated as "param_error".

       HTML::Mason::Exception::Syntax
           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".

       HTML::Mason::Exception::System
           A system call of some sort, such as a file open, failed.

           Abbreviated as "system_error".

       HTML::Mason::Exception::TopLevelNotFound
           The requested top level component could not be found.

           Abbreviated as "top_level_not_found_error".

       HTML::Mason::VirtualMethod
           Some piece of code attempted to call a virtual method which was not overridden.

           Abbreviated as "virtual_error"

FIELDS

       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.

EXCEPTION METHODS

       All of the Mason exceptions implement the following methods:

       as_brief
           This simply returns the exception message, without any trace information.

       as_line
           This returns the exception message and its trace information, all on a single line with tabs  between
           the message and each frame of the stack trace.

       as_text
           This returns the exception message and stack information, with each frame on a separate line.

       as_html
           This returns the exception message and stack as an HTML page.

       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.

EXCEPTION CLASS CHECKING

       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.

perl v5.38.2                                       2024-03-05                       HTML::Mason::Exceptions(3pm)