Matlab R2018b cannot check whether builtin function 'addvars.m' exist

Hi, I found that Matlab R2018b cannot check whether the builtin function 'addvars.m' exist. On my machine:

>> exist('addvars.m')
ans =
     0
>> exist('addvars')
ans =
     0
>> exist('plot')
ans =
     5

However, if I type:

edit addvars

It can open this builtin function (C:\Program Files\MATLAB\R2018b\toolbox\matlab\datatypes\@tabular\addvars.m). I need to check whether it exists to make my code backward compatitable. What is the reason for this issue?

Edit: A screenshot

Answer 1

[madhan ravi]

https://www.mathworks.com/help/matlab/ref/exist.html#description - reason is given.

P.S - I received the same answer as you(2018b).

Answer 2

[Walter Roberson]

The inside of @ directories are not considered to be on the search path. When exist() is passed a file name, it only examines the search path. When exist() is passed the name of a function, it only examines the search path.

The addvars that exist() is finding is considered a method of class tabular

Answer 3

[Steven Lord]

Instead of checking the existence of a particular file, I recommend using the verLessThan function to determine if the MATLAB session you're using is sufficiently new to have a particular piece of functionality. This avoids false positives where your user may create a script, function, or class file named addvars in a release earlier than its introduction as a method for table and timetable arrays in release R2018a.