1HTML::Mason::ExceptionsU(s3e)r Contributed Perl DocumentaHtTiMoLn::Mason::Exceptions(3)
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6 HTML::Mason::Exceptions - Exception objects thrown by Mason
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9 use HTML::Mason::Exceptions ( abbr => [ qw(system_error) ] );
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11 open FH, 'foo' or system_error "cannot open foo: $!";
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14 This module creates the hierarchy of exception objects used by Mason,
15 and provides some extra methods for them beyond those provided by
16 "Exception::Class"
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19 When this module is imported, it is possible to specify a list of
20 abbreviated function names that you want to use to throw exceptions.
21 In the SYNOPSIS example, we use the "system_error" function to throw a
22 "HTML::Mason::Exception::System" exception.
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24 These abbreviated functions do not allow you to set additional fields
25 in the exception, only the message.
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28 HTML::Mason::Exception
29 This is the parent class for all exceptions thrown by Mason. Mason
30 sometimes throws exceptions in this class when we could not find a
31 better category for the message.
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33 Abbreviated as "error"
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35 HTML::Mason::Exception::Abort
36 The "$m->abort" method was called.
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38 Exceptions in this class contain the field "aborted_value".
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40 HTML::Mason::Exception::Decline
41 The "$m->decline" method was called.
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43 Exceptions in this class contain the field "declined_value".
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45 HTML::Mason::Exception::Compilation
46 An exception occurred when attempting to "eval" an existing object
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49 Exceptions in this class have the field "filename", which indicates
50 what file contained the code that caused the error.
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52 Abbreviated as "compilation_error".
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54 HTML::Mason::Exception::Compiler
55 The compiler threw an exception because it received incorrect
56 input. For example, this would be thrown if the lexer told the
57 compiler to initialize compilation while it was in the middle of
58 compiling another component.
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60 Abbreviated as "compiler_error".
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62 HTML::Mason::Exception::Compilation::IncompatibleCompiler
63 A component was compiled by a compiler or lexer with incompatible
64 options. This is used to tell Mason to recompile a component.
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66 Abbreviated as "wrong_compiler_error".
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68 HTML::Mason::Exception::Params
69 Invalid parameters were passed to a method or function.
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71 Abbreviated as "param_error".
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73 HTML::Mason::Exception::Syntax
74 This exception indicates that a component contained invalid syntax.
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76 Exceptions in this class have the fields "source_line", which is
77 the actual source where the error was found, "comp_name", and
78 "line_number".
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80 Abbreviated as "syntax_error".
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82 HTML::Mason::Exception::System
83 A system call of some sort, such as a file open, failed.
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85 Abbreviated as "system_error".
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87 HTML::Mason::Exception::TopLevelNotFound
88 The requested top level component could not be found.
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90 Abbreviated as "top_level_not_found_error".
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92 HTML::Mason::VirtualMethod
93 Some piece of code attempted to call a virtual method which was not
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96 Abbreviated as "virtual_error"
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99 Some of the exceptions mentioned above have additional fields, which
100 are available via accessors. For example, to get the line number of an
101 "HTML::Mason::Exception::Syntax" exception, you call the "line_number"
102 method on the exception object.
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105 All of the Mason exceptions implement the following methods:
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107 as_brief
108 This simply returns the exception message, without any trace
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111 as_line
112 This returns the exception message and its trace information, all
113 on a single line with tabs between the message and each frame of
114 the stack trace.
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116 as_text
117 This returns the exception message and stack information, with each
118 frame on a separate line.
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120 as_html
121 This returns the exception message and stack as an HTML page.
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123 Each of these methods corresponds to a valid error_format parameter for
124 the Request object such as "text" or "html".
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126 You can create your own method in the "HTML::Mason::Exception"
127 namespace, such as "as_you_wish", in which case you could set this
128 parameter to "you_wish". This method will receive a single argument,
129 the exception object, and is expected to return some sort of string
130 containing the formatted error message.
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133 This module also exports the "isa_mason_exception" function. This
134 function takes the exception object and an optional string parameter
135 indicating what subclass to check for.
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137 So it can be called either as:
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139 if ( isa_mason_exception($@) ) { ... }
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143 if ( isa_mason_exception($@, 'Syntax') ) { ... }
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145 Note that when specifying a subclass you should not include the leading
146 "HTML::Mason::Exception::" portion of the class name.
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150perl v5.36.0 2022-07-22 HTML::Mason::Exceptions(3)