When to use local variables

[dawiinci 5]

When should I use local variables and what exactly is the difference in terms of usage and efficiency?

[Dalle1985 16]

If you use a local variable, it will be contained to the specific function or subfunction you define it in. I.e. If you run an if or a while condition and define a local variable inside that, the variable will be confined to that condition. This means that it is released from memory straight after the condition ends and it can't be used outside this condition. This is a good thing if you have many many scenes or a system with very restricted RAM (remember, Lua was written for low footprint applications, so it is often run on very low memory platforms). But RAM shouldn't be a huge issue on the HC2, so the efficiency gain in containing the variables by declaring them locals is probably negligeble and often the use of local can be confusing because you might end up declaring something a local variable even though you need to use it outside the specific body it is declared in.

I just declare the variables without the local. Then, they will be contained to the scene, but will stay in memory until the scene dies. If I have a persistent loop though, I will sometimes declare it local to reduce persistent memory consumption.

[dawiinci 5]

Thanks.

So why is this not working?

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only works if not local

[boerremk 84]

In your example the value is only known in the if statement and not outside the if statement.

[dawiinci 5]

Wow that's local. Well I changed all my locals back to normal variables. This is just too dangerous for the few kBytes of RAM.

[Dalle1985 16]

Yup... What he said.

As I wrote, it is contained to the condition you set it in. It is also a bit misleading as in other languages, it is required to define a variable as local or it will persist in memory until the scripting engine is shut down (which might actually be what is happening here, each scene is a separate virtual lua instance - ehich also explains the high load scenes put on the device).

But just avoid declaring local and it will be "global" to the scene.