Is there a way to have matlab through an error if a constant such as pi is reassigned?
in [Matlab]
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From: Craig on 20 May 2010 16:33 Hi All, I just spent several hours tracking down a code bug caused by the value pi being used as a variable. Is there a way to have matlab through an error if a constant such as pi is reassigned? Thanks, Craig
From: Walter Roberson on 20 May 2010 16:38 "Craig " <cstring625(a)yahoo.com> wrote in message <ht46a1$4ch$1(a)fred.mathworks.com>... > I just spent several hours tracking down a code bug caused by the value pi being used as a variable. Is there a way to have matlab through an error if a constant such as pi is reassigned? Sorry, Not as of 2008b. It is fairly common for a constant to be reassigned -- many programmers use i or j as variable names.
From: Matt Fig on 20 May 2010 16:45 Just out of curiosity, did you write the code? On this newsgroup folks are constantly telling others not to use words like: i j sum mean inv as variables. I don't know if there is a way to make M-Lint give a warning or not, but good programming practices will go a long way towards averting these types of problems. Perhaps M-Lint needs a service enhancement request?
From: Matt Fig on 20 May 2010 17:25 This could be of use for cases when some unknown problem is occurring in your code. Take for example, this poor function: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function [] = test_getvars() % A BAD function. a = 3; b = 4; pi = 5; % No! R = rand(7); exp = 3; % No! randperm = 4; % No! i = 3; % No! getvars % Check our ability to stay out of trouble. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% which calls this function. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% function [] = getvars() % Find out if one of the variables in a workspace is masking a built-in. WHOS_OUTPUT_1 = evalin('caller','who'); for ii = 1:length(WHOS_OUTPUT_1) S = which(WHOS_OUTPUT_1{ii}); if ~isempty(S) fprintf(['The variable ',WHOS_OUTPUT_1{ii},' may be masking a built-in.\n']) end end %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% At least it is a starting point :-).
From: TideMan on 20 May 2010 17:42 On May 21, 8:33 am, "Craig " <cstring...(a)yahoo.com> wrote: > Hi All, > I just spent several hours tracking down a code bug caused by the value pi being used as a variable. Is there a way to have matlab through an error if a constant such as pi is reassigned? > Thanks, > Craig Matlab cannot detect acts of stupidity. Even if it could and gave a warning, would you take any notice? A few years ago, I learned the hard way that using i as an index was stupid. I spent hours trying to figure out what was going wrong with my complex numbers. I never do that now. There are a few variable names that I never use: i, j, pi and g (which is usually 9.81).
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