如何对 Matlab 语言进行写保护？

Question

Matlab 允许您在没有警告的情况下覆盖内置函数。

例如，我用一个变量覆盖了函数 max()，但 Matlab 没有提醒我这一点。仅在稍后调用函数时抛出错误，并不能帮助您看到实际问题：

min     = 0;
max     = 10;
x       = linspace(min,max,20);
y       = exp(x);
disp(['the value is: ', num2str(max(y))])

错误信息：

Subscript indices must either be real positive integers or logicals.

有没有办法在启动时或在设置文件中对所有 Matlab 语言进行写保护以防止这种情况发生？

Answer 1

我不知道如何做你想做的事。但是有一种方法可以检查特定函数是否被变量或其他函数隐藏，使用which：即分析[=20=的输出]，其中 fname 是包含函数名称的字符串。

以max函数为例：比较（无阴影）

>> clear all
>> fname = 'max';
>> which(fname, '-all')
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@logical\max)  % logical method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@char\max)     % char method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@double\max)   % double method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint8\max)    % uint8 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint16\max)   % uint16 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint32\max)   % uint32 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint64\max)   % uint64 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int8\max)     % int8 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int16\max)    % int16 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int32\max)    % int32 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int64\max)    % int64 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@single\max)   % single method
C:\Program Files\MATLAB\R2010b\toolbox\matlab\timeseries\@timeseries\max.m     % timeseries method
C:\Program Files\MATLAB\R2010b\toolbox\distcomp\parallel\@codistributed\max.m  % codistributed method
C:\Program Files\MATLAB\R2010b\toolbox\shared\statslib\@ordinal\max.m          % ordinal method

有（阴影）

>> fname = 'max';
>> max = 10;
>> which(fname, '-all')
max is a variable.
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@logical\max)  % Shadowed logical method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@char\max)     % Shadowed char method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@double\max)   % Shadowed double method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint8\max)    % Shadowed uint8 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint16\max)   % Shadowed uint16 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint32\max)   % Shadowed uint32 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint64\max)   % Shadowed uint64 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int8\max)     % Shadowed int8 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int16\max)    % Shadowed int16 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int32\max)    % Shadowed int32 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int64\max)    % Shadowed int64 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@single\max)   % Shadowed single method
C:\Program Files\MATLAB\R2010b\toolbox\matlab\timeseries\@timeseries\max.m     % Shadowed timeseries method
C:\Program Files\MATLAB\R2010b\toolbox\distcomp\parallel\@codistributed\max.m  % Shadowed codistributed method
C:\Program Files\MATLAB\R2010b\toolbox\shared\statslib\@ordinal\max.m          % Shadowed ordinal method

在第二种情况下，which(fname, '-all') 告诉您 max 是一个隐藏多个方法的变量。

因此，要测试是否正在发生阴影，

将 which(fname, '-all') 的输出分配给一个变量。

原则上这可以像 s = which(fname, '-all'); 那样完成。然而，不幸的是，这会产生不同的输出；特别是，上面几行中的 % ... 部分（告诉是否有阴影）被删除：

>> fname = 'max';
>> s = which(fname, '-all')
s = 
    'variable'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@logical\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@char\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@double\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint8\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint16\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint32\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint64\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int8\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int16\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int32\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int64\max)'
    'built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@single\max)'
    'C:\Program Files\MATLAB\R2010b\toolbox\matlab\timeseries\@timeseries\max.m'
    'C:\Program Files\MATLAB\R2010b\toolbox\distcomp\parallel\@codistributed\max.m'
    'C:\Program Files\MATLAB\R2010b\toolbox\shared\statslib\@ordinal\max.m'

所以我们需要求助于evalc来获得完整的输出：s = evalc('which(fname, ''-all'')');。结果 s 是一个长字符串，包含由换行符分隔的所有行（包括 % ... 部分）：

>> fname = 'max';
>> s = evalc('which(fname, ''-all'')')
s =
max is a variable.
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@logical\max)  % Shadowed logical method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@char\max)     % Shadowed char method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@double\max)   % Shadowed double method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint8\max)    % Shadowed uint8 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint16\max)   % Shadowed uint16 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint32\max)   % Shadowed uint32 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@uint64\max)   % Shadowed uint64 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int8\max)     % Shadowed int8 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int16\max)    % Shadowed int16 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int32\max)    % Shadowed int32 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@int64\max)    % Shadowed int64 method
built-in (C:\Program Files\MATLAB\R2010b\toolbox\matlab\datafun\@single\max)   % Shadowed single method
C:\Program Files\MATLAB\R2010b\toolbox\matlab\timeseries\@timeseries\max.m     % Shadowed timeseries method
C:\Program Files\MATLAB\R2010b\toolbox\distcomp\parallel\@codistributed\max.m  % Shadowed codistributed method
C:\Program Files\MATLAB\R2010b\toolbox\shared\statslib\@ordinal\max.m          % Shadowed ordinal method

分析步骤1得到的字符串s是否包含'% Shadowed'。这很容易用 strfind 完成：即，如果有阴影，strfind(s, '% Shadowed') 将是非空的。

总结:

综合起来，

isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'));

returns true 如果名称包含在变量 fname 中的函数被隐藏，否则 false。

带有变量的示例:

>> clear all
>> fname = 'max';
>> max = 10;
>> isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'))
isShadowed =
     1
>> clear max
>> isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'))
isShadowed =
     0

具有命名函数的示例:

在文件 std.m 中创建一个函数并将其放在您的路径中。这将影响 Matlab 的 std 函数。

>> fname = 'std';
>> isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'))
isShadowed =
     1

现在删除函数文件（或从路径中删除其文件夹）：

>> fname = 'std';
>> isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'))
isShadowed =
     0

带有匿名函数的示例:

>> std = @(x) x+1;
>> fname = 'std';
>> isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'))
isShadowed =
     1
>> clear std
>> isShadowed = ~isempty(strfind(evalc('which(fname, ''-all'')'), '% Shadowed'))
isShadowed =
     0

Answer 2

截至 9/2015，我还没有找到一种方法轻松写保护原生 matlab functions/language，作为 setting/flag/etc 在启动时。

如果您关注某个特定函数，可以通过多种方式查看它们是否被隐藏，包括 Luis Mendo 的回答：which('name_of_function', '-all').

如果以后找到方法，我会很乐意接受这个答案！

如何对 Matlab 语言进行写保护？

How can I write-protect the Matlab language?

syntax

matlab

function