# Debug

## debug.isvalidlevel

```lua
<boolean> debug.isvalidlevel(<number> level)
```

Returns whether `level` is a valid level or not.

***

## debug.getregistry

```lua
<table<function | thread>> debug.getregistry()
```

Returns the lua registry.

***

## debug.getconstant

```lua
<any> debug.getconstant(<function | number> func, <number> index)
```

Returns the constant at `index` in the constant table of the function or level `func`. Throws an error if the constant does not exist.

***

## debug.getconstants

```lua
<table<any>> debug.getconstants(<function | number> func)
```

Returns the constant table of the function or level `func`.

***

## debug.getinfo

```lua
<DebugInfo> debug.getinfo(<function | number> func)
```

Returns debugger information about a function or stack level.

#### DebugInfo

| Field         | Type     | Description                                                                        |
| ------------- | -------- | ---------------------------------------------------------------------------------- |
| `source`      | string   | The name of the chunk that created the function.                                   |
| `short_src`   | string   | A "printable" version of `source` to be used in error messages.                    |
| `func`        | function | The function itself.                                                               |
| `what`        | string   | The string "Lua" if the function is a Luau function, or "C" if it is a C function. |
| `currentline` | number   | The current line where the given function is executing.                            |
| `name`        | string   | The name of the function.                                                          |
| `nups`        | number   | The number of upvalues in the function.                                            |
| `numparams`   | number   | The number of parameters in the function.                                          |
| `is_vararg`   | number   | Whether the function has a variadic argument.                                      |

***

## debug.getproto

```lua
<function | table<function>> debug.getproto(<function | number> func, <number> index, <boolean?> active)
```

Returns the proto at `index` in the function or level `func` if `active` is false.

If `active` is true, then every active function of the proto is returned.

***

## debug.getprotos

```lua
<table<function>> debug.getprotos(<function | number> func)
```

Returns a list of protos of the function or level `func`.

***

## debug.getstack

```lua
<any | table<any>> debug.getstack(<function | number> func, <number?> index)
```

Returns the value at `index` in the stack frame `level`. Throws an error if no value could be found.

If `index` is not specified, then the entire stack frame is returned.

***

## debug.getupvalue

```lua
<any> debug.getupvalue(<function | number> func, <number> index)
```

Returns the upvalue at `index` in the function or level `func`. Throws an error if the upvalue does not exist.

An upvalue is a local variable used by an inner function, and is also called an *external local variable*.

Read more on [Lua visibility rules](http://www.lua.org/manual/5.1/manual.html#2.6).

***

## debug.getupvalues

```lua
<table<any>> debug.getupvalues(<function | number> func)
```

Returns a list of upvalues of the function or level `func`.

***

## debug.setconstant

```lua
<nil> debug.setconstant(<function | number> func, <number> index, <any> value)
```

Sets the constant at `index` in the function or level `func` to `value`.

***

## debug.setstack

```lua
<nil> debug.setstack(<function | number> func, <number> index, <any> value)
```

Sets the register at `index` in the stack frame `level` to `value`.

***

## debug.setupvalue

```lua
<nil> debug.setupvalue(<function | number> func, <number> index, <any> value)
```

Sets the upvalue at `index` in the function or level `func` to `value`.

***


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