Document 'REQUIRES FUNCTION' to declare aliased functions which are required

to be provided.


git-svn-id: http://svn.cactuscode.org/flesh/trunk@3672 17b73243-c579-4c4c-a9d2-2d5706c11dac

2 files changed, 14 insertions, 2 deletions

diff --git a/doc/UsersGuide/Appendices.tex b/doc/UsersGuide/Appendices.tex
index 255b90d0..59b40cee 100644
--- a/doc/UsersGuide/Appendices.tex
+++ b/doc/UsersGuide/Appendices.tex
@@ -397,7 +397,13 @@ CCTK_FPOINTER <\var{function_arg1}>(<\var{arg1_type}> <\var{intent1}> <\var{arg1
 \end{alltt}
 Function pointers may not be nested. 
 
-If an aliased function is to be used then the block
+If an aliased function is to be required then the block
+\begin{alltt}
+REQUIRES FUNCTION <\var{alias}>
+\end{alltt}
+is required.
+
+If an aliased function is to be (optionally) used then the block
 \begin{alltt}
 USES FUNCTION <\var{alias}>
 \end{alltt}
diff --git a/doc/UsersGuide/ThornWriters.tex b/doc/UsersGuide/ThornWriters.tex
index 076203a1..266fc023 100644
--- a/doc/UsersGuide/ThornWriters.tex
+++ b/doc/UsersGuide/ThornWriters.tex
@@ -3969,7 +3969,11 @@ interface.ccl} file. Declare the prototype as, for example,
 \begin{verbatim}
 CCTK_REAL FUNCTION SumStuff(CCTK_REAL IN x, CCTK_REAL IN y)
 \end{verbatim}
-\noindent and that this function will be used in your thorn by
+\noindent and that this function will be either required in your thorn by
+\begin{verbatim}
+REQUIRES FUNCTION SumStuff
+\end{verbatim}
+\noindent or optionally used in your thorn by
 \begin{verbatim}
 USES FUNCTION SumStuff
 \end{verbatim}
@@ -3984,6 +3988,8 @@ That is, the C prototype will expect an argument with intent {\tt IN}
 to be a value and one with intent {\tt OUT} to be a pointer. There
 also exists the {\tt ARRAY} keyword for passing arrays of any
 dimension.
+Functions which are required by some thorn (which doesn't provide it itself)
+are checked at startup to be provided by some other thorn.
 
 
 \subsection{Providing a function}