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D Cookbook

By : Adam Ruppe

5 (9)

D Cookbook

5 (9)

By: Adam Ruppe

Overview of this book

D Cookbook

D Cookbook

Credits

Credits

Foreword

Foreword

About the Author

About the Author

About the Reviewers

About the Reviewers

www.PacktPub.com

www.PacktPub.com

Preface

Preface

Free Chapter

Core Tasks

Core Tasks

Introduction

Installing the compiler and writing a "Hello World" program

Adding additional modules (files) to your program

Using external libraries

Building and processing arrays

Using associative arrays to translate input

Creating a user-defined vector type

Using a custom exception type

Understanding immutability

Slicing a string to get a substring

Creating a tree of classes

Phobos – The Standard Library

Phobos – The Standard Library

Introduction

Performing type conversions

Finding the largest files in a directory

Creating a network client and server

Using Base64 to create a data URI

Generating random numbers

Normalizing a string and performing Unicode comparisons

Searching with regular expressions

Writing a digest utility

Using the std.zlib compression

Using the std.json module

Ranges

Ranges

Introduction

Using ranges when implementing an algorithm

Creating an input range

Creating an output range

Creating a higher-order range

Putting a range interface on a collection

Creating an input range over a tree structure

Using runtime polymorphic (class) ranges

Storing a range as a data member

Sorting ranges efficiently

Searching ranges

Using functional tools to query data

Integration

Integration

Introduction

Calling the Windows API functions

Removing the Windows console

Making Linux system calls

Writing part of a C program in D

Interfacing with C++

Using structs to mimic the C++ object structure

Communicating with external processes

Communicating with a dynamic scripting language

Using Windows' COM

Resource Management

Resource Management

Introduction

Avoiding the garbage collector

Making a reference-counted object

Manually managing class memory

Using scope guards to manage transactions

Creating an array replacement

Managing lent resources

Creating a NotNull struct

Using unique pointers

Using RAII and handling the limitations of class destructors

Wrapped Types

Wrapped Types

Introduction

Creating a struct with reference semantics

Simulating inheritance with structs

Creating a ranged integer

Creating an opaque handle type

Creating a subtyped string for i18n

Forwarding methods with opDispatch

Creating a tagged dynamic type

Creating a structure with two views into the same data

Simulating multiple inheritance with mixin templates

Correctness Checking

Correctness Checking

Introduction

Using assertions and exceptions

Using static asserts

Using template constraints and static if

Preventing memory corruption bugs with @safe

Leveraging const-correctness

Avoiding side effects of pure functions

Verifying object invariants and pre- and post-conditions

Unit testing your code

Documenting your code with Ddoc

Writing platform-specific code (versions) and per-client configuration modules

Reflection

Reflection

Introduction

Getting dynamic runtime type information

Getting a list of child classes

Determining whether a module is available

Getting a list of all methods or fields in a module or an object

Inspecting function overloads

Determining names, types, and default values of function parameters

Getting components of complex types

Using user-defined attributes

Implementing a custom lint-style check for virtual functions

Extending the runtime type information

Creating a command-line function caller

Code Generation

Code Generation

Introduction

Creating user-defined literals

Parsing a domain-specific language

Generating data structures from text diagrams

Automating dynamic calls with multiple dispatch

Building a lookup table

Using string parameters to change functions

Wrapping instance methods

Using opDispatch to generate properties

Duck typing to a statically-defined interface

Multitasking

Multitasking

Introduction

Using threads

Passing messages with std.concurrency

Processing parallel data with std.parallelism

Using fibers

Creating new processes

Exploring thread-safe, single-locking singletons

Using asynchronous I/O

D for Kernel Coding

D for Kernel Coding

Introduction

Running D on bare metal x86 with a stripped runtime

Adding interrupt handling to the bare metal x86 code

Web and GUI Programming

Web and GUI Programming

Introduction

Creating a dynamic website with cgi.d

Creating a web API with web.d

Parsing and modifying an HTML page with dom.d

Accessing a SQL database

Sending an e-mail

Writing colored output to the console

Getting real-time input from the terminal

Working with image files

Creating a graphics window to show a TV static demo

Creating an OpenGL window

Addendum

Addendum

Compiling D for ARM/Linux Raspberry Pi

Running D on bare metal ARM

Using the exponentiation operator

Getting a stack trace without throwing an exception

Finding more information about D

Index

Index

Getting a list of child classes

Another form of runtime information available in D is a list of all classes in the program. Using this information, we can achieve tasks that will be impossible at runtime, such as getting a list of all child classes of a particular class. A potential use of this capability will be to load game objects, defined as classes inheriting a common base, from an XML file at runtime.

How to do it…

Let's execute the following steps to get a list of child classes:

Get the typeid of the parent class you're interested in.
Loop over ModuleInfo with the foreach loop.
Loop over the localClasses member of each loop value.
Add recursion if you want to get all descendants, including the children's children.

The code is as follows:

ClassInfo[] getChildClasses(ClassInfo c) {
    ClassInfo[] info;
    foreach(mod; ModuleInfo) {
        foreach(cla; mod.localClasses) {
            if(cla.base is c)
                info ~= cla;
        }
    }

    return info;
}

class A {}
class B : A...

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