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 and object properties. It allows you to check if the variable or property is defined or not to prevent Textwire from creating an error.

defined

defined(arg: any...): boolean

Function defined checks if variables and properties are defined. It doesn't care about true, false, nil, or any other literal type, it only tells you if the variable is defined and if the property on an object is defined or not.

Arguments:

1. arg (any) - Any amount of arguments

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

Input Example:

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

Output:

Missing

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.

<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>

Another good usecase is for object properties, you can do something like this:

@if(defined(user.address.street.number))
    {{ user.address.street.number }}
@end

It prevents you from getting an error when trying to get propery on nil type if your address or street is undefined.

How it Works with Literal Types

The function defined is designed to work with variables and object properties, 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 --}}

Limitations

The defined function only checks for undefined variables and undefined properties on objects. It does not check for:

• Method calls on objects
• Function calls
• Array index out of bounds
• Type errors

If you try to use defined() with a method call that doesn't exist, it will still produce an error:

{{ name = "john"; defined(name.somemethod()) }}
{{-- Error: method 'somemethod' does not exist on type 'string' --}}

Best Practice

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

hasValue

hasValue(arg: any...): boolean

Function hasValue checks if variables and properties are defined and non-nullable. Unlike function defined, hasValue checks if the variable is not only defined but also has a non-nullable value. For example, if you have a variable x that is defined but has a value of 0, the function hasValue(x) will return false.

Arguments:

1. arg (any) - Any amount of arguments

If you pass more than 1 variable, the function will return true if all variables or properties have value.

Input Example:

{{ actors = []; hasValue(actors) ? 'Has value' : 'No value' }}

Output:

No value

Best Practice

Use hasValue() when you need to know for sure that the variable is defined and contains non-zero value.