Friday, July 11, 2014

How to Replace Global Variables by Using a Static Class

One of the first things I used to do when creating a new Delphi application was add a copy of the almighty global.pas unit to the project. I'd immediately go in to this file and start tweaking this and tweaking that so it would work with my new application. And, I made sure to ALWAYS add Globals to the uses clause of every new form I created.

My Delphi buddy Bob White, who is Scottish and speaks with a very heavy brogue, called his "Globs". Which stood for globs.pas. I remember him saying, "The programmer's life. Another day, another global." It sounds really cool with his Scottish accent.

Anyway, I thought this was the normal way of doing stuff. I thought every Delphi programmer did this. I never challenged it. Not ever.

Now, as I'm re-learning Delphi all over again for the first time, I hear several Delphi people, in the various Delphi hangouts, say stuff like, "Never use global variables" and "Pretend like global variables don't exist".

I'm thinking to myself... "Okay how the heck do you program if you can't use global variables?"

So, last weekend learned how to replace global variables in my Delphi application by using what is called a static class. It turns out that a static class can simply exist without having to be instantiated. That is pretty cool.

A static class can have constants, variables, functions and procedures. Its like having global variables on steroids. I have replaced my globasl.pas file with a file called ApplicationInfo.pas. I've included a copy of this file below.

This is a fairly new concept for me and it will no doubt go through some changes and refactoring. But so far, I'm liking it.

Here's a couple ways I'm implementing the use of my TAppInfo static class.

The cool part is the Intelisense... I just type TApp and hit [Ctrl] + [Space] and I can pick the item I want. No more "Globs" for this Marine!


Enjoy - Semper Fi,
Gunny Mike