magnum/doc/method-chaining.dox

/*
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namespace Magnum {
/** @page method-chaining Method chaining

@brief Little feature helping to reduce typing and encourage best practices.

Method chaining ([Wikipedia](http://en.wikipedia.org/wiki/Method_chaining)) is a
feature which allows you to chain method calls one after another without
repeatedly specifying variable the method is called on. Its primary goal is to
reduce unnecessary repeated names, improving code readability.

%Magnum uses this feature mainly for configuring OpenGL objects (such as
various mesh and framebuffer options, shader uniforms etc.). Because OpenGL was
designed with "bind-to-modify" approach, most configuration calls internally
need to bind the object first and only after that change the parameters (unless
@extension{EXT,direct_state_access} extension is available to avoid this). To
reduce unneeded bind calls, %Magnum binds the object only if it is not already
bound somewhere. Method chaining encourages you to configure whole object in
one run, effectively reducing the number of needed bindings. Consider the
following example:
@code
Texture2D *carDiffuseTexture, *carSpecularTexture, *carBumpTexture;

carDiffuseTexture->setStorage(5, TextureFormat::SRGB8);
carSpecularTexture->setStorage(3, TextureFormat::R8);
carBumpTexture->setStorage(5, TextureFormat::RGB8);
carDiffuseTexture->setSubImage(0, {}, diffuse);
carSpecularTexture->setSubImage(0, {}, specular;
carBumpTexture->setSubImage(0, {}, bump);
carDiffuseTexture->generateMipmap();
carSpecularTexture->generateMipmap();
carBumpTexture->generateMipmap();
@endcode

This code is written that similar configuration steps are grouped together,
which might be good when somebody needs to change something for all three
textures at once, but on the other hand the code is cluttered with repeated
names and after each configuration step the texture must be rebound to another.
With method chaining used the code looks much lighter and each object is
configured in one run, reducing count of bind calls from 9 to 3.
@code
carDiffuseTexture->setStorage(5, TextureFormat::SRGB8)
    ->setSubImage(0, {}, diffuse)
    ->generateMipmap();
carSpecularTexture->setStorage(3, TextureFormat::R8)
    ->setSubImage(0, {}, diffuse)
    ->generateMipmap();
carBumpTexture->setStorage(5, TextureFormat::RGB8)
    ->setSubImage(0, {}, bump)
    ->generateMipmap();
@endcode

Method chaining is not used on non-configuring functions, such as Framebuffer::clear()
or Mesh::draw(), as these won't be commonly used in conjunction with other
functions anyway.

Method chaining is also used in SceneGraph and other libraries and in some cases
it allows you to just "configure and forget" without even saving the created
object to some variable, for example when adding static object to an scene:
@code
Scene3D scene;

(new MyObject(&scene))
    ->rotateX(90.0_degf)
    ->translate({-1.5f, 0.5f, 7.0f});
@endcode

In most cases method chaining methods return pointer to the object, because
most of the objects are commonly created on the heap. The only exception are
Shader methods, which return reference, because the class is commonly created
as local variable in shader constructors.
*/
}