Macro that declare variables in Rust?

Question

In C its possible to write a macro that declares variables, as follows:

#define VARS(a, b, c) \ int a, b, c;

Of course this isn't something you'd typically want to do.

In the actual example I'm looking to get working its not quite so simple.

#define VARS(data, stride, a, b, c) \ MyStruct *a = &data.array[0], \ MyStruct *b = &data.array[1 * (stride)], \ MyStruct *c = &data.array[2 * (stride)];

However the exact details of assignment shouldn't matter for the purpose of this question.

Is it possible to write a macro like this in Rust? If so how would this be written?

antoyo · Accepted Answer · 2016-08-05 02:08:51Z

It is possible to write such a macro in Rust:

macro_rules! vars { ($data:expr, $stride:expr, $var1:ident, $var2:ident, $var3:ident) => { let $var1 = $data[0]; let $var2 = $data[1 * $stride]; let $var3 = $data[2 * $stride]; }; } fn main() { let array = [1, 2, 3, 4, 5]; let stride = 2; vars!(array, stride, a, b, c); println!("{}", a); println!("{}", b); println!("{}", c); }

Read the Macros chapter in the book for more information.

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