Retrieve the template directory URI via global or get_template_directory_uri() every time?

Question

One Wordpress function I happen to use frequently is get_template_directory_uri(). While I tried to minimize or avoid its use where I can, I still happen to have more than one call to this function in certain pages across my theme. Most of the time in a series of href or inside other functions (for which I normally put the URI resulting from get_template_directory_uri() in a $variable - however I still find that I might have to store again that variable in a different php file).

I wonder, would it be best if I store the returning value (my theme URI) in a global and use echo the global when I need it in different parts of my theme php files?

I'm still learning my way to best practices and uses of variables and globals.

Thank you

Answer 1

I would stay stick to the function. PHP caches functions for speed and efficiency. In some situations, using a function is faster then using a variable.

There are other benefits too - imagine if you changed the name of your variable - you would have to go and update every piece of code where it's used.

Answer 2

Global variables are hard to debug, because you cannot see easily where they are set or changed. And especially in WordPress, which suffers from too many globals already, collisions might happen, because plugin developers forget to prefix everything or they choose the same prefix as you did by accident.

Using an existing function name results in an error everyone can see and fix immediately. Using an existing global variable will silently change your code in unexpected ways.