Question

我一直在浏览Matlab的异常处理页面，在查找异常的完整最小工作示例方面有些困难，该示例由异常生成上方的调用堆栈中的函数处理。任何人都可以指向这样的页面，或确认缺少该页面吗？

谢谢。

Answer 1

我想到了下面的最小工作示例，该示例显示了将错误从已调用函数传递给调用方的机制。 TMW同意，这样的事情会填补他们文档中的空白（他们帮助创建了这个示例）。

% main.m
%-------
fprintf(1,'----------------\nRunning foo(1,2)\n')
try
   foo(1,2)
catch ME0
   ME0
end

fprintf(1,'\n');

fprintf(1,'----------------\nRunning foo(1,[2 3])\n')
try
   foo(1,[2 3])
catch ME0
   ME0
end

fprintf(1,'----------------\nRunning foo(0,4)\n')
try
   foo(0,4)
catch ME0
   ME0
end


% foo.m
%------
function foo(A,B)
   try
      barDbar(A,B)
   catch ME1
      fprintf(1,'\n');
      fprintf(1,'Running catch block in %s\n',mfilename)
      ME1, drawnow('update') % Doesn't always flush stdout !!
      % No `throw` command, error doesn't propagate to main as ME0
   end
end

% barDbar.m
%----------
function barDbar(A,B)
   try
      foobar(A,B);      
   catch ME2
      fprintf(1,'\n');
      fprintf(1,'Running catch block in %s\n',mfilename)
      ME2, drawnow('update') % Doesn't always flush stdout !!
      throw(ME2) % Required to "escalate" error to caller
   end
end

% foobar.m
%---------
function V = foobar(V1,V2)
   V = cat(1,V1,V2);               

   fprintf(1,'\n');

   % The following only executes if `cat` does *not* encounter
   % an error
   fprintf(1,'%s encountered no error.\n',mfilename)
   if V1 == 0
      fprintf(1,'Creating artificial exception instead.\n')
      ME = MException( 'foobar:ArtificalException' , ...
                       'foobar added artifical exception' );
      ME, drawnow('update') % Doesn't always flush stdout !!
      throw( ME )
   end % if
end

输出：

----------------
Running foo(1,2)

foobar encountered no error.

----------------
Running foo(1,[2 3])

Running catch block in barDbar
ME2 = 
  MException with properties:

    identifier: 'MATLAB:catenate:dimensionMismatch'
       message: 'Dimensions of matrices being concatenated are not consistent.'
         cause: {0x1 cell}
         stack: [4x1 struct]

Running catch block in foo
ME1 = 
  MException with properties:

    identifier: 'MATLAB:catenate:dimensionMismatch'
       message: 'Dimensions of matrices being concatenated are not consistent.'
         cause: {0x1 cell}
         stack: [3x1 struct]
----------------
Running foo(0,4)

foobar encountered no error.
Creating artificial exception instead.
ME = 
  MException with properties:

    identifier: 'foobar:ArtificalException'
       message: 'foobar added artifical exception'
         cause: {}
         stack: [0x1 struct]

Running catch block in barDbar
ME2 = 
  MException with properties:

    identifier: 'foobar:ArtificalException'
       message: 'foobar added artifical exception'
         cause: {}
         stack: [4x1 struct]

Running catch block in foo
ME1 = 
  MException with properties:

    identifier: 'foobar:ArtificalException'
       message: 'foobar added artifical exception'
         cause: {}
         stack: [3x1 struct]

TMW的Capture Information About Exceptions page显示了如何在每个级别（即每个try / catch块）创建一个新的异常并从较低级别的函数附加异常（而不仅仅是向上传播这些异常）。

我从该实验中发现的一件事是，异常对象不会自动在每个级别上级联成一系列的异常对象。这必须手动完成。

另一个小细节是，尽管MException可以产生异常，但它与实际错误（或使用error创建的错误）不同，因为它仍然需要显式抛出。相反，实际错误和使用error创建的错误会自动引发。

Matlab在调用堆栈中处理异常更高的最小工作示例？

1 个答案: