gstreamer/subprojects/gst-docs/markdown/additional/design/conventions.md

Documentation conventions

Due to the potential for exponential growth, several abbreviating conventions will be used throughout this documentation. These conventions have grown primarily from extremely in-depth discussions of the architecture in IRC. This has verified the safety of these conventions, if used properly. There are no known namespace conflicts as long as context is rigorously observed.

Object classes

Since everything starts with Gst, we will generally refer to objects by the shorter name, i.e. Element or Pad. These names will always have their first letter capitalized.

Function names

Within the context of a given object, functions defined in that object’s header and/or source file will have their object-specific prefix stripped. For instance, gst_element_add_pad() would be referred to as simply *add_pad(). Note that the trailing parentheses should always be present, but sometimes may not be. A prefixed asterisk (*) will always tell you it’s a function, however, regardless of the presence or absence of the trailing parentheses.

defines and enums

Values and macros defined as enums and preprocessor macros will be referred to in all capitals, as per their definition. This includes object flags and element states, as well as general enums. Examples are the states NULL, READY, PLAYING, and PAUSED; the element flags LOCKED_STATE, and state return values SUCCESS, FAILURE, and ASYNC. Where there is a prefix, as in the element flags, it is usually dropped and implied. Note however that element flags should be cross-checked with the header, as there are currently two conventions in use: with and without *FLAGS* in the middle.

Drawing conventions

When drawing pictures the following conventions apply:

objects

Objects are drawn with a box like:

+------+
|      |
+------+

pointers

a pointer to an object.

     +-----+
*--->|     |
     +-----+

an invalid pointer, this is a pointer that should not be used.

*-//->

elements

 +----------+
 | name     |
sink       src
 +----------+

pad links

-----+    +---
     |    |
    src--sink
-----+    +---