Updated 'Getting Started' with dub info.

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Ferdinand Majerech 2014-08-01 17:07:08 +02:00
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=============== ===============
Getting started Getting started
=============== ===============
Welcome to D:YAML! D:YAML is a `YAML <http://en.wikipedia.org/wiki/YAML>`_ Welcome to D:YAML! D:YAML is a `YAML <http://en.wikipedia.org/wiki/YAML>`_ parser
parser library for the `D programming language <http://dlang.org>`_. library for the `D programming language <http://dlang.org>`_. This tutorial will
This tutorial will explain how to set D:YAML up and use it in your projects. 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 is meant to be the **simplest possible** introduction to D:YAML. Some of this
this information might already be known to you. Only basic usage is covered. information might already be known to you. Only basic usage is covered.
---------- ----------
@ -18,59 +18,43 @@ Setting up
Install the DMD compiler Install the DMD compiler
^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^
Digital Mars D compiler, or DMD, is the most commonly used D compiler. You can Digital Mars D compiler, or DMD, is the most commonly used D compiler. You can find its
find its newest version `here <http://dlang.org/download.html>`_. newest version `here <http://dlang.org/download.html>`_. Download the version of DMD
Download the version of DMD for your operating system and install it. for your operating system and install it.
.. note:: .. note::
Other D compilers exist, such as Other D compilers exist, such as
`GDC <http://gdcproject.org/>`_ and `GDC <http://gdcproject.org/>`_ and
`LDC <http://bitbucket.org/goshawk/gdc/wiki/Home>`_. `LDC <http://bitbucket.org/goshawk/gdc/wiki/Home>`_.
^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^
Download and compile D:YAML Install dub
^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^
The newest version of D:YAML can be found `dub <http://code.dlang.org/about>`_ is a build system and package manager for D.
`here <https://github.com/Kiith-Sa/D-YAML>`_. Download a source archive, extract It is the standard way to manage D projects and their dependencies, compilation and so
it, and move to the extracted directory. on.
D:YAML uses a modified version of the `CDC <http://dsource.org/projects/cdc/>`_ DMD may include DUB in future releases, but at this point we need to install it
script for compilation. To compile D:YAML, you first need to build CDC. separately. See
Do this by typing the following command into the console:: `installation instructions <https://github.com/D-Programming-Language/dub#installation>`_.
dmd cdc.d
Now compile D:YAML with CDC.
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 Your first D:YAML project
------------------------- -------------------------
Create a directory for your project and in that directory, create a file called Create a directory for your project and in that directory, create a new file named
``input.yaml`` with the following contents: ``input.yaml`` and paste this code into the file:
.. code-block:: yaml .. code-block:: yaml
Hello World : Hello World : [Hello, World]
- Hello
- World
Answer: 42 Answer: 42
This will serve as input for our example. This will serve as input for our example.
Now we need to parse it. Create a file called ``main.d``. Paste following code Now we need to parse it. Create a new file with name ``main.d``. Paste following code
into the file: into the file:
.. code-block:: d .. code-block:: d
@ -99,83 +83,94 @@ into the file:
Explanation of the code Explanation of the code
^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^
First, we import the *dyaml.all* module. This is the only D:YAML module you First, we import the *dyaml.all* module. This is the only D:YAML module you need to
need to import - it automatically imports all needed modules. import - it automatically imports all needed modules.
Next we load the file using the *Loader.load()* method. *Loader* is a struct Next we load the file using the *Loader.load()* method. *Loader* is a struct used for
used for parsing YAML documents. The *load()* method loads the file as parsing YAML documents. The *load()* method loads the file as **one** YAML document, or
**one** YAML document, or throws *YAMLException*, D:YAML exception type, if the throws *YAMLException*, D:YAML exception type, if the file could not be parsed or
file could not be parsed or does not contain exactly one document. Note that we contains more than one document. Note that we don't do any error checking here in order
don't do any error checking here in order to keep the example as simple as to keep the example as simple as possible.
possible.
*Node* represents a node in a YAML document. It can be a sequence (array), *Node* represents a node in a YAML document. It can be a sequence (array), mapping
mapping (associative array) or a scalar (value). Here the root node is a (associative array) or a scalar (value). Here the root node is a mapping, and we use the
mapping, and we use the index operator to get subnodes with keys "Hello World" index operator to get subnodes with keys "Hello World" and "Answer". We iterate over the
and "Answer". We iterate over the first, as it is a sequence, and use the former, as it is a sequence, and use the *Node.as()* method on the latter to read its
*Node.as()* method on the second to read its value as an integer. value as an integer.
You can iterate over a mapping or sequence as if it was an associative or normal You can iterate over a mapping or sequence as if it was an associative or normal array,
array. If you try to iterate over a scalar, it will throw a *YAMLException*. respectively. If you try to iterate over a scalar, it will throw a *YAMLException*.
You can iterate over subnodes using *Node* as the iterated type, or specify You can iterate using *Node* as the iterated type, or specify the type iterated nodes
the type subnodes are expected to have. D:YAML will automatically convert are expected to have. D:YAML will automatically convert to that type if possible. Here
iterated subnodes to that type if possible. Here we specify the *string* type, we specify the *string* type, so we iterate over the "Hello World" sequence as an array
so we iterate over the "Hello World" sequence as an array of strings. If it is of strings. If it is not possible to convert to iterated type, a *YAMLException* is
not possible to convert to iterated type, a *YAMLException* is thrown. For thrown. For instance, if we specified *int* here, we would get an error, as "Hello"
instance, if we specified *int* here, we would get an error, as "Hello"
cannot be converted to an integer. cannot be converted to an integer.
The *Node.as()* method is used to read value of a scalar node as specified type. The *Node.as()* method is used to read value of a scalar node as specified type. If the
D:YAML will try to return the scalar as this type, converting if needed, scalar does not have the specified type, D:YAML will try to convert it, throwing
throwing *YAMLException* if not possible. *YAMLException* if not possible.
Finally we dump the document we just read to ``output.yaml`` with the Finally we dump the document we just read to ``output.yaml`` with the *Dumper.dump()*
*Dumper.dump()* method. *Dumper* is a struct used to dump YAML documents. method. *Dumper* is a struct used to dump YAML documents. The *dump()* method writes
The *dump()* method writes one or more documents to a file, throwing one or more documents to a file, throwing *YAMLException* if the file could not be
*YAMLException* if the file could not be written to. written to.
D:YAML doesn't preserve style information in documents, so even though D:YAML tries to preserve style information in documents so e.g. ``[Hello, World]`` is
``output.yaml`` will contain the same data as ``input.yaml``, it might be not turned into:
formatted differently. Comments are not preserved, either.
| ``- Hello``
| ``- World``
However, comments are not preserved and neither are any extra formatting whitespace that
doesn't affect the meaning of YAML contents.
^^^^^^^^^ ^^^^^^^^^
Compiling Compiling
^^^^^^^^^ ^^^^^^^^^
To compile your project, DMD needs to know which directories contain the We're going to use dub, which we installed at the beginning, to compile our project.
imported modules and the library. You also need to tell it to link with D:YAML.
The import directory should be the ``source`` subdirectory of the D:YAML
directory. You can specify it using the ``-I`` option of DMD. The library
directory should point to the compiled 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 and compiled D:YAML in ``/home/xxx/dyaml``, your Create a file called ``dub.json`` with the following contents:
project is in ``/home/xxx/dyaml-project``, and you are currently in that
directory, compile the project with the following command on Unix/Linux::
dmd -I../dyaml/source -L-L../dyaml -L-ldyaml main.d .. code-block:: json
And the following on Windows:: {
"name": "getting-started",
"targetType": "executable",
"sourceFiles": ["main.d"],
"mainSourceFile": "main.d",
"dependencies":
{
"dyaml": { "version" : "~>0.5.0", "path" : "../../"},
},
}
dmd -I../dyaml/source ../dyaml/libdyaml.lib main.d This file tells dub that we're building an executable called ``getting-started`` from
a D source file ``main.d``, and that our project depends on D:YAML 0.5.0 or any newer,
bugfix release of D:YAML 0.5 . DUB will automatically find and download the correct
version of D:YAML when the project is built.
This will produce an executable called ``main`` or ``main.exe`` in your Now run the following command in your project's directory::
directory. When you run it, it should produce the following output::
dub build
dub will automatically download D:YAML and compile it, and then then it will compile our
program. This will generate an executable called ``getting-started`` or
``getting-started.exe`` in your directory. When you run it, it should produce the
following output::
Hello Hello
World World
The answer is 42 The answer is 42
^^^^^^^^^^ ^^^^^^^^^^
Conclusion Conclusion
^^^^^^^^^^ ^^^^^^^^^^
You should now have a basic idea about how to use D:YAML. To learn more, look at You should now have a basic idea about how to use D:YAML. To learn more, look at the
the `API documentation <../api/index.html>`_ and other tutorials. You can find code for this `API documentation <../api/index.html>`_ and other tutorials. You can find code for this
example in the ``example/getting_started`` directory in the package. example in the ``example/getting_started`` directory in the package.