{"id":9898,"date":"2018-06-22T10:43:41","date_gmt":"2018-06-22T14:43:41","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=9898"},"modified":"2018-06-22T10:43:41","modified_gmt":"2018-06-22T14:43:41","slug":"function-handle-constructor","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2018\/06\/22\/function-handle-constructor\/","title":{"rendered":"Function Handle Constructor"},"content":{"rendered":"\r\n

Jiro<\/a>‘s pick this week is function_handle constructor<\/a> by Rody Oldenhuis<\/a>.<\/p>

When I first started programming in MATLAB, I would create my MATLAB files (scripts, functions) in my current folder. Everything is there, so I had no issues calling my scripts and functions. As I started working on multiple projects, I would create a new working folder and put everything there. After a while, I would have these similar functions that I constantly reuse. That was around the time I learned about the path<\/a>. I can put all of my utility functions in a particular folder and add that folder to my search path. Later on, I learned about other ways of organizing my code, like private functions<\/a>. When I learned about object oriented programming, I discovered the existence of packages<\/a>.<\/p>

Once in a while, I have these situations where I need to call a function that lives in some other folder, but that folder is not on the path. I just need it for that particular task, and I don’t want to add it to the path just for that task. There is a handy function called run<\/tt><\/a>, which allows you to call any script<\/em> that exist elsewhere, but it doesn’t work for functions. This is where function_handle<\/tt> by Rody comes into play.<\/p>

For example, there was a blog post I did a few years ago where I highlighted an entry that converted numbers to English names. The function isn’t on my path, but let me show you how it works. First, I’ll create a function handle<\/a> for that function. Normally, you just use the @ symbol to create a function handle. But for a function that is not on the path, it becomes a bit tricky. Here, I’ll use Rody’s function_handle<\/tt>.<\/p>

fcn = function_handle('..\\2015_01_09_Num2Words\\num2words\\num2words.m'<\/span>)\r\n<\/pre>
fcn =\r\n  function_handle with value:\r\n    @num2words\r\n<\/pre>
Now I can just call num2words<\/tt> using the function handle.<\/p>
fcn(1024)\r\n<\/pre>
ans =\r\n    'one thousand and twenty-four'\r\n<\/pre>
Comments<\/b><\/p>
Give it a try and let us know what you think here<\/a> or leave a comment<\/a> for Rody.<\/p>