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Diffstat (limited to 'system/doc/reference_manual/errors.xml')
| -rw-r--r-- | system/doc/reference_manual/errors.xml | 55 |
1 files changed, 47 insertions, 8 deletions
diff --git a/system/doc/reference_manual/errors.xml b/system/doc/reference_manual/errors.xml index e764cf431f..16d3e7590e 100644 --- a/system/doc/reference_manual/errors.xml +++ b/system/doc/reference_manual/errors.xml @@ -4,7 +4,7 @@ <chapter> <header> <copyright> - <year>2003</year><year>2015</year> + <year>2003</year><year>2017</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -49,8 +49,7 @@ The Erlang programming language has built-in features for handling of run-time errors.</p> <p>A run-time error can also be emulated by calling - <c>erlang:error(Reason)</c> or <c>erlang:error(Reason, Args)</c> - (those appeared in Erlang 5.4/OTP-R10).</p> + <c>erlang:error(Reason)</c> or <c>erlang:error(Reason, Args)</c>.</p> <p>A run-time error is another name for an exception of class <c>error</c>. </p> @@ -79,7 +78,6 @@ <p>Exceptions are run-time errors or generated errors and are of three different classes, with different origins. The <seealso marker="expressions#try">try</seealso> expression - (new in Erlang 5.4/OTP R10B) can distinguish between the different classes, whereas the <seealso marker="expressions#catch">catch</seealso> expression cannot. They are described in @@ -94,7 +92,7 @@ <cell align="left" valign="middle"><c>error</c></cell> <cell align="left" valign="middle">Run-time error, for example, <c>1+a</c>, or the process called - <c>erlang:error/1,2</c> (new in Erlang 5.4/OTP R10B)</cell> + <c>erlang:error/1,2</c></cell> </row> <row> <cell align="left" valign="middle"><c>exit</c></cell> @@ -110,14 +108,55 @@ (see <seealso marker="#exit_reasons">Exit Reason</seealso>), and a stack trace (which aids in finding the code location of the exception).</p> - <p>The stack trace can be retrieved using - <c>erlang:get_stacktrace/0</c> (new in Erlang 5.4/OTP R10B) - from within a <c>try</c> expression, and is returned for + <p>The stack trace can be be bound to a variable from within + a <c>try</c> expression, and is returned for exceptions of class <c>error</c> from a <c>catch</c> expression.</p> <p>An exception of class <c>error</c> is also known as a run-time error.</p> + + <section> + <title>The call-stack back trace (stacktrace)</title> + <p>The stack back-trace (<em>stacktrace</em>) is a list of + <c>{Module,Function,Arity,Location}</c> + tuples. The field <c>Arity</c> in the first tuple can be the + argument list of that function call instead of an arity integer, + depending on the exception.</p> + + <p><c>Location</c> is a (possibly empty) list of two-tuples + that can indicate the location in the source code of the + function. The first element is an atom describing the type of + information in the second element. The following items can + occur:</p> + <taglist> + <tag><c>file</c></tag> + <item>The second element of the tuple is a string (list of + characters) representing the filename of the source file + of the function. + </item> + <tag><c>line</c></tag> + <item>The second element of the tuple is the line number + (an integer > 0) in the source file + where the exception occurred or the function was called. + </item> + </taglist> + <warning><p>Developers should rely on stacktrace entries only for + debugging purposes.</p> + <p>The VM performs tail call optimization, which + does not add new entries to the stacktrace, and also limits stacktraces + to a certain depth. Furthermore, compiler options, optimizations and + future changes may add or remove stacktrace entries, causing any code + that expects the stacktrace to be in a certain order or contain specific + items to fail.</p> + <p>The only exception to this rule is the class <c>error</c> with the + reason <c>undef</c> which is guaranteed to include the <c>Module</c>, + <c>Function</c> and <c>Arity</c> of the attempted + function as the first stacktrace entry.</p> + </warning> + </section> + </section> + <section> <title>Handling of Run-time Errors in Erlang</title> |