# triggon

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## Overview
Dynamically switch multiple values at specific trigger points.

> ⚠️ **This library is currently in beta. 
> APIs may change in future releases, and some bugs may still be present.**

> ⚠️ Function names like `alter_var()` and `alter_literal()` have been renamed 
> to `switch_var()` and `switch_lit()` in the next update.  
> The old names will remain available during the beta period for compatibility.

## Table of Contents
- [Installation](#installation)
- [Usage](#usage)
- [License](#license)
- [Author](#author)

## Features
- Switch multiple values at once with a single trigger point
- No `if` or `match` statements needed
- Switch both literal values and variables
- Trigger early returns with optional return values
- Automatically jump to other functions at a trigger point

## Planned Feature
- Support switching beyond values and function calls—toward broader code behavior control

## Upcoming Feature
- Support for delayed trigger execution (e.g., after N seconds)

## Installation
```bash
pip install triggon
```

## Usage
This section explains how to use each function.

### Triggon 
`Triggon(self, label: str | dict[str, Any], /, new: Any=None, *, debug: bool=False)`

`Triggon()` is initialized with label-value pairs.  
You can pass a single label with its value, or multiple labels using a dictionary.

If you pass multiple values to a label using a list,  
each value will correspond to index 0, 1, 2, and so on, in the order you provide.

```python
from triggon import Triggon

# Set index 0 to 100 and index 1 to 0 as their new values
tg = Triggon("num", new=[100, 0])

def example():
    x = tg.switch_lit("num", 0)    # index 0
    y = tg.switch_lit("*num", 100) # index 1

    print(f"{x} -> {y}")

example()
# Output: 0 -> 100

tg.set_trigger("num")

example()
# Output: 100 -> 0
```

When passing a list or tuple that should be used as a single value,  
make sure to wrap it in another list or tuple to avoid it being unpacked.

```python
tg = Triggon({
    "seq1": [(1, 2, 3)], # index 0 holds (1, 2, 3)  
    "seq2": [1, 2, 3],   # indexes 0, 1, and 2 hold 1, 2, and 3
})

def example():
    x = tg.switch_lit("seq1", 10) # index 0
    y = tg.switch_lit("seq2", 10) # index 0

    print(f"For 'seq1': {x}")
    print(f"For 'seq2': {y}")

tg.set_trigger(("seq1", "seq2"))

example()
# == Output ==
# For 'seq1': (1, 2, 3)
# For 'seq2': 1
```

A single index can have multiple values assigned to it.

```python
from dataclasses import dataclass

from triggon import Triggon

tg = Triggon("mode", new=True) # Set index 0 to True for label 'mode'

@dataclass
class ModeFlags:
    mode_a: bool = False
    mode_b: bool = False
    mode_c: bool = False

    def set_mode(self, enable: bool):
        tg.set_trigger("mode", cond="enable")

        tg.switch_var("mode", [self.mode_a, self.mode_b, self.mode_c]) # All values share index 0

        print(
            f"mode_a is {self.mode_a}\n"
            f"mode_b is {self.mode_b}\n"
            f"mode_c is {self.mode_c}\n"
        )

s = ModeFlags()

s.set_mode(False)
# == Output ==
# mode_a is False
# mode_b is False
# mode_c is False

s.set_mode(True)
# == Output ==
# mode_a is True
# mode_b is True
# mode_c is True
```

If you want to trace label activity in real time, set the `debug` keyword to `True`.

> ⚠️ **Note:** 
Labels with the `*` prefix cannot be used during initialization 
and will raise an `InvalidArgumentError`.

### set_trigger
`def set_trigger(self, label: str | list[str] | tuple[str, ...], /, *, cond: str=None) -> None`

Marks the specified label(s) as triggered, 
allowing their values to be updated on the next call.  
All values associated with the specified label will be changed, regardless of their index.  
The `label` parameter accepts a single string or a list/tuple of labels.

You can set conditions using the `cond` keyword 
but control structures such as `if` are not allowed.

If any of the specified labels have been disabled using `revert()`, 
this function has no effect on them.

```python
from triggon import Triggon

tg = Triggon({
    "milk": 3,
    "banana": 0.4,
    "msg": "We're having a sale for milk today!",
})

def example():
    msg = tg.switch_lit("msg", org="We're open as usual today.")
    print(msg)

    milk = tg.switch_lit('milk', 4)
    banana = tg.switch_lit('banana', 0.6)

    print(f"Milk: ${milk}")
    print(f"Banana: ${banana}")

example()
# == Output ==
# We're open as usual today.
# Milk: $4
# Banana: $0.6

tg.set_trigger(["milk", "msg"]) # Triggers for 'milk' and 'msg' are activated here.

example()
# == Output ==
# We're having a sale for milk today!
# Milk: $3
# Banana: $0.6
```

```python
tg = Triggon("msg", "Call me?")

def sample(print_msg: bool):
    # Activate "msg" if print_msg is True
    tg.set_trigger("msg", cond="print_msg")

    # Print the message if triggered
    print(tg.switch_lit("msg", ""))

sample(False) # Output:
sample(True)  # Output: Call me? 
```

> **Note:**
This function uses `eval()` internally to evaluate the `cond` argument.
However, **only comparison expressions (e.g., `x > 0 > y`, `value == 10`) are allowed**.
Non-comparison expressions will raise an `InvalidArgumentError`.

### switch_lit (alter_literal)
`def switch_lit(self, label: str | list[str] | tuple[str, ...], /, org: Any, *, index: int=None) -> Any`

Changes a literal value when the flag is active.  
You can also use this function directly inside a print().  
When using a dictionary for `label`, the `index` keyword cannot be used.

```python
from triggon import Triggon

tg = Triggon("text", new="After") 

def example():
    text = tg.switch_lit("text", org="Before", index=0)
    print(text)  

    # You can also write: 
    # print(tg.alter_literal('text', 'Before'))

    tg.set_trigger("text")

example() # Output: Before
example() # Output: After
```

Alternatively, you can use the `*` character as a prefix to specify the index.  
For example, `"label"` refers to index 0, and `"*label"` refers to index 1.

You can use the `index` keyword or the `*` prefix.  
When both are provided, the keyword takes precedence.  
`*` used elsewhere (not as a prefix) is ignored and has no special meaning.

> **Note:**   
For better readability when working with multiple indices, 
it's recommended to use the `index` keyword.

```python
# Set the value to 'A' for index 0 and to 'B' for index 1
tg = Triggon("char", new=("A", "B"))

def example():
    tg.set_trigger("char")

    print(tg.switch_lit("char", 0))           # index 0 (no '*' — defaults to index 0)
    print(tg.switch_lit("*char", 1))          # index 1 (using '*')
    print(tg.switch_lit("*char", 0, index=0)) # index 0 ('index' keyword takes precedence over '*')
    print(tg.switch_lit("char", 1, index=1))  # index 1 (using 'index' keyword)

example()
# == Output ==
# A
# B
# A
# B
```

```python
tg = Triggon({"A": True, "B": False})

def sample():
    # Applies the new value if any label is active.
    # If both are active, the earlier one takes priority.
    x = tg.switch_lit(["A", "B"], None)

    print(x)

sample()            # Output: None 

tg.set_trigger("A") # Output: True
sample()

tg.set_trigger("B") # Output: True
sample()
```

> **Note:**   
When multiple labels are passed and multiple flags are active,  
the earliest label in the sequence takes precedence.
In that case, if the `index` keyword is passed,  
it will be applied to all labels.

### switch_var (alter_var)
`def switch_var(self, label: str | dict[str, Any], var: Any=None, /, *, index: int=None) -> None | Any`

Changes variable value(s) directly when the flag is active.  
**It supports global variables and class attributes, but not local variables.**

You can pass multiple labels and variables using a dictionary.    
The `index` keyword cannot be used in that case.  
If the target index is 1 or greater, 
add a `*` prefix to the label corresponding to the index  
(e.g., `*label` for index 1, `**label` for index 2).

This function returns the updated value **only when a single label is passed**.  
If a dictionary is passed, the function returns `None`.

> **Note:**  
In such cases, it is recommended to use individual calls to this function  
with the `index` keyword instead, for better readability.

```python
import random

from triggon import Triggon

tg = Triggon({
    "level_1": ["an uncommon", 80],
    "level_2": ["a rare", 100],
    "level_3": ["a legendary", 150],
})

level = None
attack = None

def spin_gacha():
    items = ["level_1", "level_2", "level_3"]
    result = random.choice(items)

    tg.set_trigger(result)

    tg.switch_var(result, level)
    tg.switch_var(result, attack, index=1)

    # Outputs vary randomly.
    # Example: result = 'level_2'
    print(f"You pulled {level} sword!") # Output: You pulled a rare sword!
    print(f"Attack Power: {attack}")    # Output: Attack Power: 100 

spin_gacha()
```

```python
from dataclasses import dataclass

from triggon import Triggon

tg = Triggon("even", [0, 2, 4])

@dataclass
class Example:
    a: int = 1
    b: int = 3
    c: int = 5

    def change_field_values(self, change: bool):
        if change:
            tg.set_trigger("even")

        tg.alter_var({
            "even": self.a,    # index 0
            "*even": self.b,   # index 1
            "**even": self.c,  # index 2
        })

exm = Example()

exm.change_field_values(False)
print(f"a: {exm.a}, b: {exm.b}, c: {exm.c}")
# Output: a: 1, b: 3, c: 5

exm.change_field_values(True)
print(f"a: {exm.a}, b: {exm.b}, c: {exm.c}")
# Output: a: 0, b: 2, c: 4
```

Also, you can assign multiple values to a single variable.

```python
tg = Triggon({
    "flag": [True, False],
    "num": [0, 100],
})

@dataclass
class Sample:
    flag: bool = None
    num: int = None

    def sample(self, label: str, label_2: str):
        tg.switch_var({label: self.flag, label_2: self.num})

        print(f"flag is {self.flag} and num is {self.num}")

s = Sample()
tg.set_trigger(["flag", "num"])

s.sample("flag", "num")   # Output: flag is True and num is 0
s.sample("*flag", "*num") # Output: flag is False and num is 100
```

> **Notes:** 
> Values are typically updated when `set_trigger()` is called.  
> However, on the first call, 
> the value won't change unless the variable has been registered via `switch_var()`.  
> In that case, the value is changed by `switch_var()`.  
> Once registration is complete, each call to `set_trigger()` immediately updates the value.  
>
> In some environments (e.g., Jupyter or REPL),  
> calls to alter_var or switch_var may not be detected due to source code unavailability.
>
> This function only supports  
> literal values, variables, or simple attribute chains for labels and the `index` keyword.  
> Other types will raise an `InvalidArgumentError`.

### revert
`def revert(self, label: str | list[str] | tuple[str, ...]=None, /, *, all: bool=False, disable: bool=False) -> None`

Reverts all values previously changed by `switch_lit()` or `switch_var()`  
to their original state.  
To revert all labels, set the `all` keyword to `True`.

The reversion remains effective until the next call to `set_trigger()`.  
All values associated with the specified label will be reverted, 
regardless of their index.

If the `disable` keyword is set to `True`, the reversion becomes permanent.

```python
from dataclasses import dataclass

from triggon import Triggon

tg = Triggon("hi", new="Hello")

@dataclass
class User:
    name: str = "Guest"
    init_done: bool = False

    def initialize(self):
        # Set the trigger for the first-time greeting
        tg.set_trigger("hi")

        self.init_done = True
        self.greet()

    def greet(self):
        msg = tg.switch_lit("hi", org="Welcome back")
        print(f"{msg}, {self.name}!")

    def entry(self):
        if self.init_done:
            self.greet()
        else:
            self.initialize()
            tg.revert("hi") # Revert to the original value

user = User()

user.entry() # Output: Hello, Guest!

user.entry() # Output: Welcome back, Guest!
```

```python
tg = Triggon({"name": "John", "state": True})

@dataclass
class User:
    name: str = None
    online: bool = False

    def login(self):
        # Set the variable for each label
        tg.switch_var({"name": self.name, "state": self.online})
        tg.set_trigger(["name", "state"])

user = User()
print(f"User name: {user.name}\nOnline: {user.online}")
# == Output ==
# User name: None
# Online: False

user.login()
print(f"User name: {user.name}\nOnline: {user.online}")
# == Output ==
# User name: John
# Online: True
```

### exit_point
`def exit_point(self, label: str, func: TrigFunc, /) -> None | Any`

Defines the exit point where an early return is triggered by `trigger_return()`.  
The `func` argument must be a `TrigFunc` instance that wraps the target function.  

An index with the `*` prefix can be used, but it is ignored.

> **Note:** `exit_point()` is not required if `trigger_return()` is not triggered.

### trigger_return
`trigger_return(self, label: str, /, ret: Any=None, *, index: int=None, do_print: bool=False) -> None | Any`

Triggers an early return with any value when the flag is active.  
The return value must be set during initialization.  
If nothing needs to be returned, set it to `None` or simply omit the value..

You can also set the return value with the `ret` keyword,  
which takes precedence over the one set during initialization.
In that case, you don't need to provide any value if you're not using a dictionary.

If the `do_print` keyword is set to `True`, the return value will be printed.  
If the value is not a string, an `InvalidArgumentError` is raised.

```python
from triggon import Triggon, TrigFunc

# Define label and early-return value
tg = Triggon("skip", new="(You don't have enough money...)")
F = TrigFunc() # Wraps the target function for early return

def check_funds(money: int):
    if money < 300:
        tg.set_trigger("skip")

    print(f"You now have {money}G.")
    board_ship()

def board_ship():
    print("It'll cost you 300G to board the ship.")

    # Triggers early return and prints the value if the flag is set
    tg.trigger_return("skip", do_print=True) 

    print("Enjoy the ride!")  

tg.exit_point("skip", F.check_funds(500))
# == Output ==
# You now have 500G.
# It'll cost you 300G to board the ship.
# Enjoy the ride!

tg.exit_point("skip", F.check_funds(200))
# == Output ==
# You now have 200G.
# It'll cost you 300G to board the ship.
# (You don't have enough money...)
```

```python
tg = Triggon("zero")
F = TrigFunc()

def sample():
    num = get_number()

    # The "zero" label will be activated if `num` is 0
    tg.set_trigger("zero", cond="num == 0")

    # Return early with the message if triggered
    tg.trigger_return("zero", ret=f"{num} ...", do_print=True) 

    num_2 = get_number()

    print(f"The total number is {num + num_2}!")

def get_number():
    return random.randint(0, 10) 

tg.exit_point("zero", F.sample()) # The output is random!
```

### trigger_func
`def trigger_func(self, label: str, func: TrigFunc, /) -> None | Any`

Triggers a function when the flag is active.  
The `func` argument must be a `TrigFunc` instance that wraps the target function.

A label must be initialized with any value in order to register it when creating a `Triggon` instance.  
The value won't be returned, so you can use any placeholder.  
If you're not using a dictionary, there's no need to provide a value at all.  
**If the function returns a value, that value will also be returned.**.

An index with the `*` prefix can be used, but it is ignored.

```python
from triggon import Triggon, TrigFunc

tg = Triggon({
    "skip": None,
    "call": None,
})
F = TrigFunc()

def example():
    tg.set_trigger(["skip", "call"]) # Set triggers for early return and function call

    print("If the 'call' flag is active, jump to example_2().")

    tg.trigger_func("call", F.example_2()) # Use the TrigFunc instance F for example_2()

    print("This message may be skipped depending on the trigger.")


def example_2():
    print("You’ve reached the example_2() function!")
    tg.trigger_return("skip")

tg.exit_point("skip", F.example())
# == Output ==
# If the 'call' flag is active, jump to example_2().
# You’ve reached the example_2() function!
```

### TrigFunc
This class wraps a function to delay its execution.   
You can create an instance without any arguments and use it to wrap the target function.

> ⚠️ **Note:**  
When using this class,  
you must create an instance first (e.g., F = TrigFunc()) before using it.

### Error
- `InvalidArgumentError`  
Raised when the number of arguments, their types, or usage is incorrect.

- `MissingLabelError`
Raised when a specific label has not been registered.

## License
This project is licensed under the MIT License.  
See [LICENSE](./LICENSE) for details.

## Author
Created by Tsuruko  
GitHub: [@tsuruko12](https://github.com/tsuruko12)  
X: [@tool_tsuruko12](https://x.com/tsuruko)
