[LUA] Use _G["var"] or array?

[sethmachine]

Hi,

What is better style/practice if I want to reference a collection of variables that have the same name/form, but only differ on a parameter, e.g.

var_1
var_2
var_3
...

Would I make an array instead?

var[0] = "1"
var[1] = "2"
var[2] = "3"

and then reference the array member?

for i=0, 2 do
print(var)

or

for i=0, 2 do
print(_G["var_" .. i])

 

[PurgeandFire]

I would go with the array option. Using variable names is generally less conventional.

 

[Death Adder]

It should be faster to only make one variable with array instead of several, no?

 

[sethmachine]

With N arbitrary values, still need N lines if I'm filling an array or N variables.

But yes the array works much better for loops anyway, and I chose that.

Thank you.

 

[Dr Super Good]

Arrays should be used when some form of dynamic memory access is required. If you are only ever accessing memory statically the index argument just adds overhead which degrades performance. In C/C++ the compiler will likely treat constant array indices as a static address offset (like a struct) or even constant addresses (if the array itself is in statically allocated memory) so emphasis is on readability.

Sadly WC3 does not do this and instead it will evaluate your constant index argument and pass it as an array index every time you access the array adding considerable overhead over using a separate variable. This is an extremely bad programming practice that was unfortunately encouraged by several people years ago resulting in a lot of poorly written GUI spells in the spell section.

Using constant array indices as part of an initialization stage or specific access stage is perfectly acceptable. As long as an index can be target of at least one dynamic index access then any constant index accesses done to it is fine and use of an array is justified. If an array only has constant index accesses then there is no reason ever to use an array as separate variables provide identical functionality.

 

[sethmachine]

Fortunately this script only gets called once and only once, so the array access time won't matter (it's a LUA array anyway), as it just makes the custom objects.

 

[Dr Super Good]

it's a LUA array anyway

WC3 cannot execute LUA. It is either a JASS array or does not exist.

If it is a LUA save time macro then do whatever you want or looks best to you since there is no concern with speed.