+ they're much faster and can't fail.
+
+ When the target class is known statically, it's slightly more convenient to
+ use the @|SOD_CONVERT| macro than the @|sod_convert| function, since the
+ class object name is longer and uglier, and the macro returns a pointer of
+ the correct type.
+\end{describe*}
+
+
+\subsection{Instance lifecycle}
+\label{sec:runtime.object.lifecycle}
+
+The following macros and functions manage the standard steps along an
+instance's lifecycle.
+
+\subsubsection{Low-level operations}
+The following macros and functions are agnostic with respect to storage
+allocation strategies. They don't concern themselves with allocation or
+deallocation, and applications are free to use any suitable mechanism.
+
+\begin{describe*}
+ {\dhead[SOD_INIT]{mac}
+ {@<cls> *SOD_INIT(@<cls>, void *@<p>, @<keywords>);}
+ \dhead[sod_init]{fun}
+ {void *sod_init(const SodClass *@<cls>, void *@<p>, \dots);}
+ \dhead[sod_initv]{fun}
+ {void *sod_initv(const SodClass *@<cls>, void *@<p>, va_list @<ap>);}}
+ Imprints and initializes an instance of a class @<cls> in the storage
+ starting at address~@<p>.
+
+ The direct class for the new instance is specified as a class name to
+ @|SOD_INIT|, or a pointer to a class object to the functions.
+
+ Keyword arguments for the initialization message may be provided. The
+ @|SOD_INIT| macro expects a single preprocessor-time argument which is
+ a use of one of \descref{KWARGS}{mac} or \descref{NO_KWARGS}{mac}; the
+ @|sod_init| function expects the keywords as a variable-length argument
+ tail; and @|sod_initv| expects the keywords to be passed indirectly,
+ through the captured argument-tail cursor @<ap>.
+
+ The return value is an instance pointer for the class @<cls>; the
+ @|SOD_INIT| macro will have converted it to the correct type, so it should
+ probably be used where possible. In fact, this is guaranteed to be equal
+ to @<p> by the layout rules described in
+ \xref{sec:structures.layout.instance}.
+\end{describe*}
+
+\subsubsection{Automatic storage duration}
+The following macro constructs an instance with automatic storage duration.
+
+\begin{describe}[SOD_DECL]{mac}{SOD_DECL(@<cls>, @<var>, @<keywords>);}
+ Declares and initializes an instance with automatic storage duration.
+
+ Given a class name @<cls> and an identifier @<var>, @|SOD_DECL| declares
+ @<var> to be a pointer to an instance of @<cls>. The instance is
+ initialized in the sense that its vtable and class pointers have been set
+ up, and slots for which initializers are defined are set to the appropriate
+ initial values.
+
+ Keyword arguments for the initialization message may be provided. The
+ macro expects a single preprocessor-time argument which is a use of one of
+ \descref{KWARGS}{mac} or \descref{NO_KWARGS}{mac}.
+
+ The instance has automatic storage duration: pointers to it will become
+ invalid when control exits the scope of the declaration.