https://github.com/elliotchance/reflect
🪞 Runtime reflection for V (vlang)
https://github.com/elliotchance/reflect
vlang vlang-awesome vlang-library vlang-module
Last synced: 4 months ago
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🪞 Runtime reflection for V (vlang)
- Host: GitHub
- URL: https://github.com/elliotchance/reflect
- Owner: elliotchance
- License: mit
- Created: 2021-07-15T04:47:52.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2021-08-04T03:52:06.000Z (about 4 years ago)
- Last Synced: 2025-06-14T04:03:20.801Z (4 months ago)
- Topics: vlang, vlang-awesome, vlang-library, vlang-module
- Language: V
- Homepage:
- Size: 33.2 KB
- Stars: 28
- Watchers: 2
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
elliotchance.reflect
====================
Runtime reflection for [V](https://vlang.io).
V does not carry runtime information about types. Although compile-time
reflection is more performant it can be limiting in some cases that can't be
avoided.
*IMPORTANT: This project is more to demonstrate that a lot of the runtime
reflection functionality one might need can be done without technically using
runtime types. This implementation relies on static code being generated from
compile-time reflection for known types going into the appropriate
constructors.*
- [Installation](#installation)
- [Values](#values)
- [Types](#types)
- [Arrays](#arrays)
- [Maps](#maps)
- [Structs](#structs)
Installation
------------
```bash
v install elliotchance.reflect
```
Values
------
A `Value` can be created from any literal or simple value, for example:
```v
import elliotchance.reflect
fn main() {
v := reflect.value_of(1.23)
println(v.typ) // "f64"
println(v.get_f64()) // 1.23
println(v.get_int()) // V panic: value must be int but is f64
}
```
This becomes especially useful when dealing with arrays of mixed types:
```v
// Only sum numbers.
fn sum(items []reflect.Value) f64 {
mut total := 0.0
for item in items {
match item.typ.kind {
.is_f64 { total += item.get_f64() }
.is_int { total += item.get_int() }
else { /* ignore */ }
}
}
return total
}
fn main() {
v := [
reflect.value_of(1.23),
reflect.value_of("hello"),
reflect.value_of(7),
]
println(sum(v)) // 8.23
}
```
Types
-----
All `Values` have a `Type` which can be accessed on the `.typ` field.
- `.kind`: one of the `Kind` values: `is_bool`, `is_string`, `is_i8`, `is_i16`,
`is_int`, `is_i64`, `is_byte`, `is_u16`, `is_u32`, `is_u64`, `is_rune`,
`is_f32`, `is_f64`.
- `.elem`: Only applies for arrays, describes the element type.
- `.str()`: The string representation that matches the compile-time type in V.
Arrays
------
```v
import elliotchance.reflect
fn main() {
v := reflect.array_of([5, 6, 7])
println(v.typ) // "[]int"
println(v.typ.kind) // "array"
println(v.typ.elem.kind) // "int"
println(v.len()) // 3
println(v.cap()) // 3
println(v.get_index(1).get_int()) // 6
println(v.get_index(5)) // V panic: array index 5 is out of bounds (len = 3)
}
```
Maps
----
```v
import elliotchance.reflect
fn main() {
mut m := map[string]int{}
m['a'] = 5
m['b'] = 7
m['c'] = 9
v := reflect.map_of(m)
println(v.typ) // "map[string]int"
println(v.typ.kind) // "map"
println(v.typ.key.kind) // "string"
println(v.typ.elem.kind) // "int"
println(v.len()) // 3
println(v.keys()) // ['a', 'b', 'c']
println(v.get_key(reflect.value_of('b')).get_int()) // 7
println(v.get_key(reflect.value_of('d'))) // V panic: key not found: d
println(v.get_key(reflect.value_of(123))) // V panic: value must be string but is int
}
```
Structs
-------
```v
import elliotchance.reflect
struct Foo {
a int
b f64
c string
}
fn main() {
s := Foo{123, 4.56, 'hello'}
v := reflect.struct_of(&s)
println(v.typ) // "main.Foo"
println(v.typ.kind) // "struct"
println(v.fields()) // ['a', 'b', 'c']
println(v.field('b').typ) // "f64"
println(v.field('b').get_f64()) // 4.56
println(v.field('d')) // V panic: field not found: d
v.field('b').set_string('hi') // V panic: value must be f64 but is string
v.field('c').set_string('hi')
println(v.field('c').get_string()) // "hi"
println(s.c) // "hi"
}
```