In MATLAB you can have multiple functions in one .m
file. There is of course the main function, and then either nested or local functions.
Examples of each function type:
% myfunc.m with local function ------------------------------------------
function myfunc()
disp(mylocalfunc());
end
function output = mylocalfunc()
% local function, no visibility of variables local to myfunc()
output = 'hello world';
end
% -----------------------------------------------------------------------
% myfunc.m with nested function -----------------------------------------
function myfunc()
disp(mynestedfunc());
function output = mynestedfunc()
% nested function, has visibility of variables local to myfunc()
output = 'hello world';
end
end
% ----------------------------------------------------------------------
The difference is clear when you use the functions' end
statements. However, I don't think it's clearly documented which you are using when you don't, since this is valid syntax:
% myfunc.m with some other function
function myfunc()
disp(myotherfunc());
function output = myotherfunc()
% It's not immediately clear whether this is nested or local!
output = 'hello world';
Is there any clear definition of whether functions written like myotherfunc
are local or nested?
You can write n number of functions in a single m file.
A nested function is a function that is completely contained within a parent function. Any function in a program file can include a nested function.
no, there's nothing wrong with that at all, and in js, it's usually a good thing. the inside functions may not be a pure function, if they rely on closure variables. If you don't need a closure or don't need to worry about polluting your namespace, write it as a sibling.
Inner functions, also known as nested functions, are functions that you define inside other functions. In Python, this kind of function has direct access to variables and names defined in the enclosing function.
This can be quickly tested because of the variable scope differences mentioned in the documentation
The primary difference between nested functions and local functions is that nested functions can use variables defined in parent functions without explicitly passing those variables as arguments.
So adapting the question example:
function myfunc()
% Define some variable 'str' inside the scope of myfunc()
str = 'hello world';
disp(myotherfunc());
function output = myotherfunc()
% This gives an error because myotherfunc() has no visibility of 'str'!
output = str;
This errors because myotherfunc
is in fact a local function, not a nested function.
The test is supported by the documentation for nested functions which states:
Typically, functions do not require an
end
statement. However, to nest any function in a program file, all functions in that file must use anend
statement.
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