I am sure this issue has been debated before. By now, I have learned that all global variables must be constants. But I am less clear on global variables that are a function of other global variables, already defined as const. For example: const var1 = 3 var2= 3 * var1 Must var2 be defined as con…

[image] Henrique_Becker: but var1 has not? Not sure I follow. The type of var 1 is known: it is an integer, in this case. It can change. In my example, var2 is of type integer as well (i.e., the same type as var1. But as was already mentioned, after compilation, I could change the type of eit…

You didn’t include the global variable in the definition of tst2.

I am sure @dpsanders is much more knowledgeable than I am, but I find necessary to point that The word const is really a misnomer. It is not that the variable is constant. It is the variable type that is constant, which is quite different. Is just completely wrong. The binding is constant, not t…

I admit I am a beginner in Julia, which is why I am posting. Consider my duplication of the example provided by @dpsanders : julia> const cc = 3 3 julia> const cc =5 WARNING: redefining constant cc 5 WARNING: redefining constant zzz Note that the printout is different and my constant changed. I…

This is just a convenience to be used in the REPL instead of re-starting it. If you check the manual section on constants you will find: Note that although sometimes possible, changing the value of a const variable is strongly discouraged, and is intended only for convenience during interactive u…

Thank you. So the bottom line seems to be (as I have read in several places): (this does make a greater impact when one is actually programming as opposed to simply reading.) do not use globals if you use globals, the preference is not to use const if efficiency is the desired outcome, use struct…

About your list, well, let me give you my more nuanced (and incredibly verbose) vision: Avoid globals. Specially for parameters. Just use a Dict, or create your own struct and pass it along (there some package solutions too). I use globals. I have a global timer in my module, so I can reset it, ru…

[image] erlebach: if you use globals, the preference is not to use const This really depends on your application. If the value is actually a constant, use const. If you want a mutable container, also use const. [image] erlebach: the preference is to use immutable structs for maximum effi…

Great answer!!! Yes, my answer was very crude in comparison. I will perhaps perform some experiments. My preference is not to use goals. Passing known types via function arguments is my preference. Thanks again! I hope this helps others. I have nothing to add. Gordon

[image] Tamas_Papp: If the function gets the value as a parameter , then it does not matter. That is good to know! However, wouldn’t that only be true if the parameter values had specified types? For example: a = 35 function anyfunc(a::Int64) ... end would be as efficient as using const…

[image] erlebach: would be less efficient, since the type of a could change and the compiler has to take that into account. No, not at all. With few exceptions, the function signature has no effect on the performance of the code within that function.

Const variables

New to Julia

StefanKarpinski Split this topic February 7, 2022, 2:36pm 31

6 posts were split to a new topic: Typeconst proposal

Topic		Replies	Views
Efficiently passing a set of constants to a function Performance functions , constants	21	2703	July 8, 2022
Fast alternative to mutable struct Performance question	10	5446	February 13, 2020
How to correctly define and use global variables in the module in Julia? General Usage	19	18762	August 6, 2021
Initialization of container of constants? NamedTuple, etc General Usage	17	359	August 16, 2024
Typeconst proposal Internals & Design proposal , constants	33	2503	February 9, 2022

Const variables

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