1Mojo::Exception(3) User Contributed Perl Documentation Mojo::Exception(3)
2
6 Mojo::Exception - Exception base class
7
9 # Create exception classes
10 package MyApp::X::Foo {
11 use Mojo::Base 'Mojo::Exception';
12 }
13 package MyApp::X::Bar {
14 use Mojo::Base 'Mojo::Exception';
15 }
16 # Throw exceptions and handle them gracefully
18 use Mojo::Exception qw(check);
19 eval {
20 MyApp::X::Foo->throw('Something went wrong!');
21 };
22 check $@ => [
23 'MyApp::X::Foo' => sub { say "Foo: $_" },
24 'MyApp::X::Bar' => sub { say "Bar: $_" }
25 ];
26 # Generate exception classes on demand
28 use Mojo::Exception qw(check raise);
29 eval {
30 raise 'MyApp::X::Name', 'The name Minion is already taken';
31 };
32 check $@ => [
33 'MyApp::X::Name' => sub { say "Name error: $_" },
34 default => sub { say "Error: $_" }
35 ];
36
38 Mojo::Exception is a container for exceptions with context information.
39
41 Mojo::Exception implements the following functions, which can be
42 imported individually.
43 check
45 my $bool = check $err => ['MyApp::X::Foo' => sub {...}];
46 Process exceptions by dispatching them to handlers with one or more
48 matching conditions. Exceptions that could not be handled will be
49 rethrown automatically. Note that this function is EXPERIMENTAL and
50 might change without warning!
51 # Handle various types of exceptions
53 eval {
54 dangerous_code();
55 };
56 check $@ => [
57 'MyApp::X::Foo' => sub { say "Foo: $_" },
58 qr/^Could not open/ => sub { say "Open error: $_" },
59 default => sub { say "Something went wrong: $_" }
60 ];
61 Matching conditions can be class names for ISA checks on exception
63 objects, or regular expressions to match string exceptions and
64 stringified exception objects. The matching exception will be the first
65 argument passed to the callback, and is also available as $_.
66 # Catch MyApp::X::Foo object or a specific string exception
68 eval {
69 dangerous_code();
70 };
71 check $@ => [
72 'MyApp::X::Foo' => sub { say "Foo: $_" },
73 qr/^Could not open/ => sub { say "Open error: $_" }
74 ];
75 An array reference can be used to share the same handler with multiple
77 conditions, of which only one needs to match. And since exception
78 handlers are just callbacks, they can also throw their own exceptions.
79 # Handle MyApp::X::Foo and MyApp::X::Bar the same
81 eval {
82 dangerous_code();
83 };
84 check $@ => [
85 ['MyApp::X::Foo', 'MyApp::X::Bar'] => sub { die "Foo/Bar: $_" }
86 ];
87 There is currently only one keywords you can use to set special
89 handlers. The "default" handler is used when no other handler matched.
90 # Use "default" to catch everything
92 eval {
93 dangerous_code();
94 };
95 check $@ => [
96 default => sub { say "Error: $_" }
97 ];
98 raise
100 raise 'Something went wrong!';
101 raise 'MyApp::X::Foo', 'Something went wrong!';
102 Raise a Mojo::Exception, if the class does not exist yet (classes are
104 checked for a "new" method), one is created as a Mojo::Exception
105 subclass on demand. Note that this function is EXPERIMENTAL and might
106 change without warning!
107
109 Mojo::Exception implements the following attributes.
110 frames
112 my $frames = $e->frames;
113 $e = $e->frames([$frame1, $frame2]);
114 Stack trace if available.
116 # Extract information from the last frame
118 my ($package, $filename, $line, $subroutine, $hasargs, $wantarray, $evaltext,
119 $is_require, $hints, $bitmask, $hinthash) = @{$e->frames->[-1]};
120 line
122 my $line = $e->line;
123 $e = $e->line([3, 'die;']);
124 The line where the exception occurred if available.
126 lines_after
128 my $lines = $e->lines_after;
129 $e = $e->lines_after([[4, 'say $foo;'], [5, 'say $bar;']]);
130 Lines after the line where the exception occurred if available.
132 lines_before
134 my $lines = $e->lines_before;
135 $e = $e->lines_before([[1, 'my $foo = 23;'], [2, 'my $bar = 24;']]);
136 Lines before the line where the exception occurred if available.
138 message
140 my $msg = $e->message;
141 $e = $e->message('Died at test.pl line 3.');
142 Exception message, defaults to "Exception!".
144 verbose
146 my $bool = $e->verbose;
147 $e = $e->verbose($bool);
148 Show more information with "to_string", such as "frames", defaults to
150 the value of the "MOJO_EXCEPTION_VERBOSE" environment variable.
151
153 Mojo::Exception inherits all methods from Mojo::Base and implements the
154 following new ones.
155 inspect
157 $e = $e->inspect;
158 $e = $e->inspect($source1, $source2);
159 Inspect "message", "frames" and optional additional sources to fill
161 "lines_before", "line" and "lines_after" with context information.
162 new
164 my $e = Mojo::Exception->new;
165 my $e = Mojo::Exception->new('Died at test.pl line 3.');
166 Construct a new Mojo::Exception object and assign "message" if
168 necessary.
169 to_string
171 my $str = $e->to_string;
172 Render exception. Note that the output format may change as more
174 features are added, only the error message at the beginning is
175 guaranteed not to be modified to allow regex matching.
176 throw
178 Mojo::Exception->throw('Something went wrong!');
179 Throw exception from the current execution context.
181 # Longer version
183 die Mojo::Exception->new('Something went wrong!')->trace;
184 trace
186 $e = $e->trace;
187 $e = $e->trace($skip);
188 Generate stack trace and store all "frames", defaults to skipping 1
190 call frame.
191 # Skip 3 call frames
193 $e->trace(3);
194 # Skip no call frames
196 $e->trace(0);
197
199 Mojo::Exception overloads the following operators.
200 bool
202 my $bool = !!$e;
203 Always true.
205 stringify
207 my $str = "$e";
208 Alias for "to_string".
210
212 Mojolicious, Mojolicious::Guides, <https://mojolicious.org>.
213perl v5.34.0 2022-01-21 Mojo::Exception(3)