`addCause`

Attaches an underlying exception to an MException as one of its causes.

Category: Programming > Programming Utilities

Syntax

baseME = addCause(baseME, cause)

Returns a copy of baseME whose cause list also holds the exception cause.

Description

Errors often have a chain of reasons: a report could not be built because a file could not be read, which failed because a folder was missing. addCause records each lower-level exception in the cause property of the top-level one, a cell array, so the full chain travels together when the exception is thrown and can be inspected after it is caught.

Input arguments

baseME: The high-level MException that describes the failure.
cause: An MException describing a lower-level reason.

Output arguments

baseME: The updated exception. Assign it back; the original object is not modified.

Example

Recording a cause

ME = MException('app:load', 'Could not load data');
cause = MException('io:missing', 'File not found');
ME = addCause(ME, cause);
disp(numel(ME.cause))
disp(ME.cause{1}.message)

Output

     1
File not found

addCause