Global Functions

Global functions are not attached to any specific type like strings or integers, they are globally available everywhere. They are similar to Golang len(), cap() functions.

This global function should be used only with variables. It allows you to check if the variable is defined or not to prevent Textwire from creating an error.

defined

defined(arg: any...): bool

Arguments:

1. arg (any) - Any amount of arguments

If you pass more than 1 variable, the function will return true if all variables are defined.

Input example:

{{ defined(actors) ? 'Defined' : 'Missing' }}

Output:

Defined

When to Use It?

You can use it inside of your components when you need to check if variable was passed to the component or not. Here is the example when the book variable is required but author is optional.

components/book.tw

<div class="book">
    <h1>{{ book.title }}</h1>
    <p>{{ book.description }}</p>

    @if(defined(author))
        <small>The author is {{ author.first }} {{ author.last }}</small>
    @else
        <small>The author is unknown</small>
    @end
</div>

How it Works with Literal Types

The function defined is designed to work with variables, but if you try to call it on any literal type it will always return true. Here is the example:

{{ defined("") ? 'Yes' : 'No' }} <!-- Output: Yes -->
{{ defined(0) ? 'Yes' : 'No' }} <!-- Output: Yes -->
{{ defined(nil) ? 'Yes' : 'No' }} <!-- Output: Yes -->
{{ defined(false) ? 'Yes' : 'No' }} <!-- Output: Yes -->
{{ defined(true) ? 'Yes' : 'No' }} <!-- Output: Yes -->
{{ defined({}) ? 'Yes' : 'No' }} <!-- Output: Yes -->
{{ defined([]) ? 'Yes' : 'No' }} <!-- Output: Yes -->

Best Practice

Use defined() when working with optional variables in components to avoid runtime errors when the variable is not passed to the template.