From b4f204d57ddaccb66ca9707c0081be7d0cfcfbd9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Legat?= <benoit.legat@gmail.com>
Date: Sun, 14 Jul 2019 15:45:49 +0200
Subject: [PATCH] Add get_fallback in doc

---
 docs/src/apireference.md | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/docs/src/apireference.md b/docs/src/apireference.md
index 2bdb4f5b46..1a1ee9773b 100644
--- a/docs/src/apireference.md
+++ b/docs/src/apireference.md
@@ -44,6 +44,23 @@ set
 supports
 ```
 
+### Fallbacks
+
+The value of some attributes can be inferred from the value of other
+attributes. For instance, the value of [`ObjectiveValue`](@ref) can be computed
+using [`ObjectiveFunction`](@ref) and [`VariablePrimal`](@ref). When a solver
+gives access to the objective value, it is better to return this value but
+otherwise, [`Utilities.get_fallback`](@ref) can be used.
+```julia
+function MOI.get(optimizer::Optimizer, attr::MOI.ObjectiveValue)
+    return MOI.Utilities.get_fallback(optimizer, attr)
+end
+```
+
+```@docs
+Utilities.get_fallback
+```
+
 ### Submit
 
 Objects may be submitted to an optimizer using [`submit`](@ref).