docid: classes-codegen-function

title: CodegenFunction

layout: docs

permalink: /docs/classes/CodegenFunction/

`CodegenFunctionBase` provides shared functionality for methods and functions;

`CodegenFunction` does not add to it. The recommended way to get an instance of

`CodegenFunction` is to call `->codegenFunction('function_name()')` on an instance of

`IHackCodegenFactory`.

Basics

- `->setReturnType(string $type)`: set the return type of the function if

generating Hack code

- `->setIsAsync(bool)`: if the function should use the `async` keyword or not. This

doesn't affect the return type - include `Awaitable<>` in `setReturnType()` if

appropriate

- `->addParameter(string $param)`: add a parameter to the signature. `$param` should

include both the type and variable name - you can use

`->addParameterf($format, ...)` for complicated cases

- `->setBody(string $code)`: set the body (implementation) of the function. You

should generally use `HackBuilder` to create the string

- `->setManualBody(bool $manual = true)`: if true, make the entire function body a

manual section. If called, `->setBody()` is still used for the default value when

generating a new file.

Attributes

To make a function memoized (adding the `<<__Memoize>>` attribute), call

`->setIsMemoized(bool $value = true)`; for other attributes, call

`->setUserAttribute(string $name, ?string $value)`.

CodegenMethod

Methods are created with `$factory->codegenMethod('methodName')`, and have some

additional features over functions:

- `->setIsOverride(bool $value = true)`: add the `<<__Override>>` attribute, which

requires that the method is declared in a parent class

- `->setIsFinal(bool $value = true)`: mark the method as final

- `->setIsAbstract(bool $value = true)`: mark the method as abstract

- `->setIsStatic(bool $value = true)`: mark the method as static

FIXMEs

In some cases, you need to add an `HH_FIXME` or similar to the method declaration -

for example, variadics are not support in Hack before HHVM 3.15, so a fixme is

needed for all variadic functions.

Call `->addHHFixMe(int $code, string $why)` to add `/* HH_FIXME[$code] $why */` to

the function declaration.

Metadata

`CodegenFunctionBase` supports `->setDocBlock(string)` and

`->setGeneratedFrom(CodegenGeneratedFrom)` in the same way as `CodegenFile`.

docid: classes-other

title: Other Classes

layout: docs

permalink: /docs/classes/other/

CodegenMethod

See [CodegenFunction](/hack-codegen/docs/classes/CodegenFunction/#codegenmethod)