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Referencing Functions

They cannot be stored in variables, passed as an argument to another service, or be returned from other functions. This is for performance reasons.

To reference a function by its name at runtime, (e.g., to store it in a variable, or pass it to another function as an argument) one must use the call or funcref helpers:

Remember the default functions like _init, and most notifications such as _enter_tree, _exit_tree, _process, _physics_process, etc. are called in all base classes automatically. So, there is only a need to call the function explicitly when overloading them in some way.

Static functions

A function is always declared static. When a function is static, it is access to the instance member variables or self. This is used to make libraries of helper functions;

Statements and control flow

They are standard and can be assignments, function calls, control flow structures, etc. (see below); as a statement, the separator is entirely optional.

If/else/elif

Simple conditions are created by using the if/else/elif syntax. The parenthesis around conditions are allowed, but not required. Given the nature of the tab-based indentation, elif can be used instead of else/if to maintain a level of indentation.

Short statements can be written on the same line as the condition:

Sometimes we might want to assign a different initial based on a Boolean expression. In this case, ternary-if expressions come in handy:

while

Loops are created by using while syntax. Loops can be broken using break or continued using continue:

while [expression]:

    statement(s)

for

To iterate through a range, like an array or table, a for loop is used. When iterating over an array, the array element h stored in the loop variable. When iterating a dictionary, the index has b is stored in the loop variable.

Match

A match statement is used to branch the execution of a program. It is equivalent to the switch statement found in many other languages but offers some additional features.

Syntax:

Switch statements:

  1. Replace the switch with match
  2. Remove case
  3. Remove any breaks. If we don't want to break by default, we can use continue for a fall through.
  4. Change default to a single underscore.

Control flow:

The pattern is matched from top to bottom. If a pattern matches, the execution continues below the match statement.

If we want to have a fall through, we can use continue to stop execution in the current block and check the ones below it.

There are six pattern types:

  • Constant pattern:
    Constant primitives are numbers and strings
  • Variable pattern
    It matches the contents of a variable/enum
  • Wildcard pattern
    This pattern matches everything. It is written as a single underscore.
    It is used as the equivalent of the default in a switch statement in other languages.
  • Binding pattern
    A binding pattern introduces a new variable. Like the wildcard pattern, it matches everything -and also gives the value a name. It is useful in array and dictionaries.
  • Array pattern
    Every single element in the array pattern is a pattern itself so we can nest them. The length of the array is tested; it has to be the same size as the pattern; otherwise, it cannot match.
    Open-ended array: An array is bigger than the pattern by making the last subpattern.
    Every sub pattern is separated by a comma.
  • Dictionary pattern
    It works the same as the array pattern. Every key has a constant pattern. The size of the dictionaries is tested; first, it has the same size as the pattern; otherwise, the pattern does not match.
    Open-ended dictionaries: A dictionaries can be more significant than the pattern by making the previous subpattern...
    Every subpattern has to be comma-separated.
    If we do not specify a value, then only the existence of the key is checked.
    A value pattern is separated from a key pattern with a:

Multi patterns:

We can also specify multiple patterns separated by a comma. These patterns are not allowed to have any bindings in them.






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