https://github.com/perry-mitchell/hot-patcher
Hot method patching framework for handling environmental method differences
https://github.com/perry-mitchell/hot-patcher
hot-replacement override patch patching
Last synced: 11 months ago
JSON representation
Hot method patching framework for handling environmental method differences
- Host: GitHub
- URL: https://github.com/perry-mitchell/hot-patcher
- Owner: perry-mitchell
- License: mit
- Created: 2018-07-21T14:09:00.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2023-07-17T11:32:44.000Z (over 2 years ago)
- Last Synced: 2025-04-19T17:57:59.696Z (11 months ago)
- Topics: hot-replacement, override, patch, patching
- Language: JavaScript
- Size: 514 KB
- Stars: 3
- Watchers: 2
- Forks: 2
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Funding: .github/FUNDING.yml
- License: LICENSE
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README
# Hot-Patcher
> Hot method patching framework for handling environmental method differences
 [](https://www.npmjs.com/package/hot-patcher)
## About
Hot-Patcher provides a simple API to manage patched methods. I found while writing [Buttercup](https://buttercup.pw) that managing overwritten methods between environments (Node/Browser/React-Native) was becoming cumbersome, and having a single _agreed-upon_ method of doing so was the best way to go.
## Installation
Install Hot-Patcher from [npm](https://www.npmjs.com/package/hot-patcher):
```shell
npm install hot-patcher --save
```
**NB:** This is an ESM library.
## Usage
Hot-Patcher is a class and can simply be instantiated:
```typescript
import { HotPatcher } from "hot-patcher";
const hp = new HotPatcher();
```
Hot-Patcher is designed to be used with patchable tools:
```typescript
import { HotPatcher } from "hot-patcher";
export class MyHelper {
public patcher: HotPatcher;
constructor() {
this.patcher = new HotPatcher();
}
increment(arg: number): number {
return this.patcher.patchInline("increment", someArg => {
return someArg + 1;
}, arg);
}
}
```
You can then patch methods when required:
```typescript
import { MyHelper } from "./MyHelper.js";
export function getHelper() {
const helper = new MyHelper();
helper.patch("increment", (val: number) => val + 2);
return helper;
}
```
Patched methods can easily be fetched later:
```typescript
import { getSharedPatcher } from "./patching.js";
const randomString = getSharedPatcher().get("randomString");
randomString(5); // Generates a random string
// Or, execute the method directly:
getSharedPatcher().execute("randomString", 5) // Generates a random string
```
You can check if a method is patched by using `isPatched`: `patcher.isPatched("some method")`.
### Inline patching and execution
Ideally you could wrap function implementation with a patch call, executing it on demand:
```typescript
function add(a: number, b: number): number {
return patcher.patchInline("add", (a, b) => a + b, a, b);
}
patcher.isPatched("add"); // false
add(1, 2); // 3
patcher.isPatched("add"); // true
// calling add() multiple times will call the patched method without "re-patching" it
// over and over again..
```
### Plugins - Chaining/Sequencing functions
You can use Hot-Patcher to create sequences of functions:
```typescript
patcher.plugin("increment", x => x * 2, x => x * 2);
patcher.execute("increment", 2); // 8
```
Which is basically syntactic sugar for a regular `patch()` call:
```typescript
patcher
.patch("increment", x => x * 2, { chain: true })
.patch("increment", x => x * 2, { chain: true });
patcher.execute("increment", 2); // 8
```
Executing a regular `patch()` without `chain: true` will overwrite all chained methods with the new method.
Calling `patch()` with `chain: true` when a method already exists will simply add the new method after the existing:
```typescript
patcher
.patch("increment", x => x * 2, { chain: false }) // or simply without `chain` specified
.patch("increment", x => x * 2, { chain: true });
patcher.execute("increment", 2); // still 8
```
### Restoring methods
Methods can be restored to their _originally patched function_ by calling the `restore` method:
```typescript
const methodA = () => {};
const methodB = () => {};
patcher
// methodA is now the current (and original)
.patch("someMethod", methodA)
// methodB is now the current
.patch("someMethod", methodB);
// Restore "someMethod" to methodA (original)
patcher.restore("someMethod");
```
## Use Sparingly
The intention of Hot-Patcher is not to push every method into a patching instance, but to provide a common API for specific methods which _require_ patching in some specific environments or in situations where users/consumers are expected to provide their own custom implementations.