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https://github.com/uriopass/inline_tweak
Tweak a Rust value directly in the source code
https://github.com/uriopass/inline_tweak
Last synced: 4 days ago
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Tweak a Rust value directly in the source code
- Host: GitHub
- URL: https://github.com/uriopass/inline_tweak
- Owner: Uriopass
- License: cc0-1.0
- Created: 2020-08-30T09:40:16.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-02-04T13:13:51.000Z (11 months ago)
- Last Synced: 2024-12-15T11:42:58.640Z (11 days ago)
- Language: Rust
- Size: 83 KB
- Stars: 164
- Watchers: 7
- Forks: 8
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
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README
# inline_tweak
[](https://crates.io/crates/inline_tweak)
**inline_tweak** is based on [this blogpost](http://blog.tuxedolabs.com/2018/03/13/hot-reloading-hardcoded-parameters.html)
by tuxedo labs.
Tweak any literal directly from your code, changes to the source appear while running the program.
It works by parsing the file when a change occurs.
The library is minimal, only requiring the `lazy_static` dependency to hold modified values.
In release mode, the tweaking code is disabled and compiled away.
The `derive` feature exposes a proc macro to turn all literals from a function body into tweakable values.
## Usage
```rust
use inline_tweak::*;
fn main() {
loop {
println!("{}", tweak!(3.14)); // Try changing the value while the application is running
}
}
```
## Extra features
### derive
The `derive` feature allows to tweak any number/bool/char literal in a function.
It avoids cluttering the code with `inline_tweak::tweak!` calls.
```rust
#[inline_tweak::tweak_fn]
fn main() {
loop {
let v = 1.0; // Try changing this value!
println!("{}", v);
std::thread::sleep(Duration::from_millis(200)); // or even this value :)
}
}
```
Note that it requires `syn`/`quote`/`proc_macro2` dependencies which makes the crate slower to compile.
Contrary to `tweak!`, it does not allow tweaking literals in macro calls (like `println!`), as it cannot reliably replace literals by a function call since macros can have custom syntax.
#### watch!
`inline_tweak` provides a `watch!()` macro that sleeps until the file is modified, akin to a breakpoint:
```rust
use inline_tweak::*;
fn main() {
loop {
println!("{}", tweak!("hello world"));
watch!(); // The thread will sleep here until anything in the file changes
}
}
```
#### Expressions
`inline_tweak` allows to tweak expressions by providing a value later.
For example:
```rust
tweak!(rng.gen_range(0.0, 1.0))
```
can then be replaced by a constant value by modifying the file (even while the application is running) to
```rust
tweak!(5.0; rng.gen_range(0.0, 1.0)) // will always return 5.0
```
[See the "expression" example in action](https://i.imgur.com/pSvLNlI.mp4)
Note that this works only for expressions that return a tweakable type. (number/boolean literals)
#### release_tweak!
The `release_tweak!` macro acts exactly like `tweak!` except that it also works in release mode.
It is accessible behind the feature flag `"release_tweak"` which is not enabled by default.
## Installation
Simply add this line to your Cargo.toml
```toml
inline_tweak = "1.0.10"
```