array.get

[khalyomede]

Describe the feature

Today if we access an index that do not exist on an array, the program panics:

items := [1, 2, 3]
item := items[4] // panic

V can accept a or statement, but this is not enforced by the compiler:

items := [1, 2, 3]
item := items[4] or {5} // 5

I think we should add a "safe" index lookup method, for those who want to ensure they always get an expected value.

items := [1, 2, 3]
item := items.get(4) or {5} // 5

The array.get method should return an Option (so the program is not valid unless a fallback is provided).

Use Case

Just to not forget to use a fallback, or if the program access a non existing index.

Proposed Solution

I tried to write a polyfill for []string arrays, but the attempt failed.

Other Information

It seems there is a private get method.

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

Version used

V 0.4.7 e03bd3f

Environment details (OS name and version, etc.)

V full version: V 0.4.7 e03bd3f
OS: linux, Linux version 6.8.0-48-generic (buildd@lcy02-amd64-040) (x86_64-linux-gnu-gcc-12 (Ubuntu 12.3.0-1ubuntu122.04) 12.3.0, GNU ld (GNU Binutils for Ubuntu) 2.38) #4822.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Oct 7 11:24:13 UTC 2
Processor: 8 cpus, 64bit, little endian, Intel(R) Core(TM) i7-10510U CPU @ 1.80GHz

getwd: /home/v
vexe: /opt/vlang/v
vexe mtime: 2024-09-26 07:47:51

vroot: OK, value: /opt/vlang
VMODULES: OK, value: /root/.vmodules
VTMP: OK, value: /tmp/v_0

env VFLAGS: "-cc gcc"

Git version: git version 2.40.3
Git vroot status: e03bd3f (370 commit(s) behind V master)
.git/config present: true

CC version: cc (Alpine 12.2.1_git20220924-r10) 12.2.1 20220924
thirdparty/tcc status: thirdparty-linuxmusl-amd64 a3e24da2

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[jorgeluismireles]

Another approach could be enforce the use of unsafe for the direct access of the elements.

items := [1, 2, 3]
item := unsafe { items[4] } // panic in your behalf