When to use and when not to use global variables?

When to use and when not to use global variables?

When Not to Use: Global variables are dangerous because the only way to ever know how the global variable changed is to trace the entire source code within the .c file within which they are declared (or, all .c files if it is extern as well).

When to use a variable as a constant?

If the variable will never change, then it is a constant, not a variable. If the variable requires universal access, then two subroutines should exist for getting and setting it, and they should be synchronized. If the program starts small, and might be larger later, then code as if the program is large today, and abolish global variables.

When to use globals for runtime configuration?

Personally, I use globals for runtime configuration – if a configuration property is loaded at application startup, and only changes infrequently (and only then from one place), it’s terrible and error-prone to pass it around to every method that might need to use it at some point.

When to use singleton pattern for global variables?

If you feel that you can’t solve your problem without them, you are probably doing something wrong. Also, look into Singleton pattern, it cold provide a better solution for globals in those situations when you need something to have global access point. The problem with global variables is that you need to be aware of them everywhere in your code.

Why are global variables so bad in Python?

Why are globals bad? “This has nothing to do with Python; global variables are evil in any programming language.” Because the experts say so, and because it reveals that one is probably a noob coder if using too many globals. Apparently, the occasional global here and there is okay in certain circumstances, i.e, a short bit of code.

Why do we use global variables in PHP?

The use of globals in a function introduce additional parameters which are not document in the function declaration. globals don’t have any specific initialization construct and therefor you can never be sure when you can access the value of the global, and you don’t get any error when trying to access the global before initialization.

Why are global variables not used in WordPress?

WordPress already caches these things in the object cache/memory so it doesn’t have to fetch it multiple times in the same request, you don’t need to store the result and reuse, WP does that already out of the box. It’s very likely your code is running slower as a result of this micro-optimisation, not faster!