Variables

Scriggo allows you to declare new variables in a template in addition to the global ones.

Declaration

A variable to be used, must first be declared with the var keyword:

{% var welcome = "hello" %}

or with a short assignment:

{% welcome := "hello" %}

Variables declared in a template can be used in the same way as the global variables:

{% var amount = 50 %}

shipping is free for an amount of at least ${{ amount }} 

shipping is free for an amount of at least $50

Variable's type

Each variable has a type and its type is the type of the value assigned to it at declaration time. The type can also be specified explicitly in the declaration. For example:

{% var a string %}    a has type string and value ""
{% var b int %}       b has type int and value 0
{% var c bool %}      c has type bool and value false
{% var e []string %}  e has type []string and value nil

The following declarations are like the previous ones but with an initial value:

{% var a = "hello" %}                    a has type string and value "hello"
{% var b = 5 %}                          b has type int and value 5
{% var c = true %}                       c has type bool and value true
{% var e = []string{"ciao", "hello"} %}  e has type []string and value []string{"hello", "ciao"}

Assignment

Once a variable is declared, its value can be changed at any time with an assignment. The type, on the other hand, cannot change, so only values of the same type can be assigned to the variable.

{% greatings = "hello" %}

There are several other assignment statements that combine the assignment with an operator:

Writing is like writing
a++ a = a + 1
a-- a = a - 1
a += b a = a + b
a -= b a = a - b
a *= b a = a * b
a /= b a = a / b
a %= b a = a % b

Visibility

The global variables are visible in all template files and in any part of the code. Instead, the visibility of the variables declared in the code depends on where they are declared:

  • if a variable is declared in a file with an extends statement or in an imported file, and not in a block (like the body of a macro, function or statement), it is visible in all file.

  • if a variable is declared in a block (like the body of a macro, function or statement), it is visible from its declaration up to the end of the block.

  • in the other cases it is visible from its declaration to the end of the file.

Examples

In the following example, the variable n is visible both inside and outside the if statement. The variable s is visible only in the body of the if.

{% var n = 3 %}
{% if n > 2 %}
  {% var s = "hello" %}
  {{ n }}{{ s }}
{% end if %}
{{ n }}

In this other example, the variable n is not visible in the "column.html" file.

{% n := 3 %}
{{ render "column.html" }}

A macro can be used to make its value available in another file. In this other example, the value of the variable n is passed as an argument to the Column macro which could be declared in another file:

{% n := 3 %}
{{ Column(n) }}

Multiple declarations and assignments

Declarations and assignments with = allow you to declare and assign more variable at the same time.

This example:

{% var n, s = 5, "ciao" %}

{% n, s = 2, "hello" %}

is equivalent to this one:

{% var n = 5 %}
{% var s = "ciao" %}

{% n = 2 %}
{% s = "hello" %}

The short assignment is a bit more complex, therefore read the Go language documentation before using it with multiple variables.

Multiple assignment is useful for example for swap the values of two variables:

{% a, b = b, a %}

and multiple declaration and assignment are useful for assigning the return values of a function call that return two or more values:

{% var d, err = parseDecimal("12.99") %}