Nested functions

Up to this point, we have been defining functions, structs, and classes in the outermost scopes (i.e., the module scope). They can be defined in inner scopes as well. Defining them in inner scopes helps with encapsulation by narrowing the visibility of their symbols, and creating closures, which we covered in the function pointers, delegates, and lambdas chapter.

As an example, the following outerFunc() function contains definitions of a nested function, a nested struct, and a nested class:

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void outerFunc(int parameter) {
    int local;

    void nestedFunc() {
        local = parameter * 2;
    }

    struct NestedStruct {
        void memberFunc() {
            local /= parameter;
        }
    }

    class NestedClass {
        void memberFunc() {
            local += parameter;
        }
    }

    // Using the nested definitions inside this scope:

    nestedFunc();

    auto s = NestedStruct();
    s.memberFunc();

    auto c = new NestedClass();
    c.memberFunc();
}

void main() {
    outerFunc(42);
}

Introduction

Lifetimes, null Value and the is Operator

Type Conversions

Structs

Variable Number of Parameters

Function Overloading and Member Functions

Constructor and Other Special Functions

Operator Overloading

Introduction to Classes

Inheritance

The Object Class

Interfaces

destroy and scoped

Modules and Libraries

Encapsulation and Protection Attributes

UFCS, Properties and Contract Programming

Templates

Pragmas, alias and with

Pointers

Bit Operations

Conditional Compilation

Function Pointers, Delegates, and Lambdas

foreach with Structs and Classes

Unions, Labels, goto and Tuples

More Templates

More Functions

Mixins

Ranges

static foreach and Parallelism

Message Passing Concurrency

Data Sharing Concurrency

Fibers

Memory Management

User Defined Attributes (UDA) and Operator Precedence

Conclusion

Nested Functions, Structs, and Classes

Nested functions