=============== Getting started =============== Welcome to D:YAML! D:YAML is a `YAML `_ parser library for the `D programming language `_. This tutorial will explain how to set D:YAML up and use it in your projects. This is meant to be the **simplest possible** introduction to D:YAML. Some of this information might already be known to you. Only basic usage is covered. ---------- Setting up ---------- ^^^^^^^^^^^^^^^^^^^^^^^^ Install the DMD compiler ^^^^^^^^^^^^^^^^^^^^^^^^ Digital Mars D compiler, or DMD, is the most commonly used D compiler. You can find its newest version `here `_. Download the version of DMD for your operating system and install it. .. note:: Other D compilers exist, such as `GDC `_ and `LDC `_. Setting up with either one of them should be similar to DMD, however, at the moment they are not as up to date as DMD. ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Download and compile D:YAML ^^^^^^^^^^^^^^^^^^^^^^^^^^^ The newest version of D:YAML can be found `here `_. Download a source archive, extract it, and move to the extracted directory. D:YAML uses a modified version of the `CDC `_ script for compilation. To compile D:YAML, you first need to build CDC. Do this by typing the following command into the console:: dmd cdc.d Now you can use CDC to compile D:YAML. To do this on Unix/Linux, use the following command:: ./cdc On Windows:: cdc.exe This will compile the library to a file called ``libdyaml.a`` on Unix/Linux or ``libdyaml.lib`` on Windows. ------------------------- Your first D:YAML project ------------------------- Create a directory for your project and in that directory, create a file called ``input.yaml`` with the following contents: .. code-block:: yaml Hello World : - Hello - World Answer: 42 This will serve as input for our example. Now we need to parse it. Create a file called "main.d". Paste following code into the file: .. code-block:: d import std.stdio; import yaml; void main() { yaml.Node root = yaml.load("input.yaml"); foreach(string word; root["Hello World"]) { writeln(word); } writeln("The answer is ", root["Answer"].get!int); } ^^^^^^^^^^^^^^^^^^^^^^^ Explanation of the code ^^^^^^^^^^^^^^^^^^^^^^^ First, we import the *yaml* module. This is the only module you need to import to use D:YAML - it automatically imports all needed modules. Next we load the file using the *yaml.load()* function - this loads the file as **one** YAML document and throws *YAMLException*, D:YAML exception type, if the file could not be parsed or does not contain exactly one document. Note that we don't do any error checking here in order to keep the example as simple as possible. *yaml.Node* represents a node in a YAML document. It can be a sequence (array), mapping (associative array) or a scalar (value). Here the root node is a mapping, and we use the index operator to get subnodes with keys "Hello World" and "Answer". We iterate over the first, as it is a sequence, and use the *yaml.Node.get()* method on the second to get its value as an integer. You can iterate over a mapping or sequence as if it was an associative or normal array. If you try to iterate over a scalar, it will throw a *YAMLException*. You can iterate over subnodes using yaml.Node as the iterated type, or specify the type subnodes are expected to have. D:YAML will automatically convert iterated subnodes to that type if possible. Here we specify the *string* type, so we iterate over the "Hello World" sequence as an array of strings. If it is not possible to convert to iterated type, a *YAMLException* is thrown. For instance, if we specified *int* here, we would get an error, as "Hello" cannot be converted to an integer. The *yaml.Node.get()* method is used to get value of a scalar node as specified type. D:YAML will try to return the scalar as specified type, converting if needed, throwing *YAMLException* if not possible. ^^^^^^^^^ Compiling ^^^^^^^^^ To compile your project, you must give DMD the directories containing import modules and the library. You also need to tell it to link with D:YAML. The import directory should be the D:YAML package directory. You can specify it using the ``-I`` option of DMD. The library directory should point to where you put the compiled D:YAML library. On Unix/Linux you can specify it using the ``-L-L`` option, and link with D:YAML using the ``-L-l`` option. On Windows, the import directory is used as the library directory. To link with the library on Windows, just add the path to it relative to the current directory. For example, if you extracted D:YAML to ``/home/xxx/dyaml`` and compiled it in that directory, your project is in ``/home/xxx/dyaml-project``, and you are currently in that directory, you can compile the project with the following command on Unix/Linux:: dmd -I../dyaml -L-L../dyaml -L-ldyaml main.d And the following on Windows:: dmd -I../dyaml ../dyaml/libdyaml.lib main.d This will produce an executable called ``main`` or ``main.exe`` in your directory. When you run it, it should produce the following output:: Hello World The answer is 42 ^^^^^^^^^^ Conclusion ^^^^^^^^^^ You should now have a basic idea about how to use D:YAML. To learn more, look at the `API documentation <../api/index.html>`_ and other tutorials. You can find code for this example in the ``example/getting_started`` directory in the package.