Add warning to preparation (#253)

Author: gdalle

DifferentiationInterface/src/first_order/derivative.jl

@@ -6,7 +6,9 @@
 
 Create an `extras` object subtyping [`DerivativeExtras`](@ref) that can be given to derivative operators.
 
-Beware that in the two-argument case, `y` is mutated by `f!` during preparation.
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
+    In the two-argument case, `y` is mutated by `f!` during preparation.
 """
 function prepare_derivative end
 

DifferentiationInterface/src/first_order/gradient.jl

@@ -4,6 +4,9 @@
     prepare_gradient(f, backend, x) -> extras
 
 Create an `extras` object subtyping [`GradientExtras`](@ref) that can be given to gradient operators.
+
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
 """
 function prepare_gradient end
 

DifferentiationInterface/src/first_order/jacobian.jl

@@ -6,7 +6,9 @@
 
 Create an `extras` object subtyping [`JacobianExtras`](@ref) that can be given to Jacobian operators.
 
-Beware that in the two-argument case, `y` is mutated by `f!` during preparation.
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
+    In the two-argument case, `y` is mutated by `f!` during preparation.
 """
 function prepare_jacobian end
 

DifferentiationInterface/src/first_order/pullback.jl

@@ -6,7 +6,9 @@
 
 Create an `extras` object subtyping [`PullbackExtras`](@ref) that can be given to pullback operators.
 
-Beware that in the two-argument case, `y` is mutated by `f!` during preparation.
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
+    In the two-argument case, `y` is mutated by `f!` during preparation.
 """
 function prepare_pullback end
 

DifferentiationInterface/src/first_order/pushforward.jl

@@ -6,8 +6,9 @@
 
 Create an `extras` object subtyping [`PushforwardExtras`](@ref) that can be given to pushforward operators.
 
-Beware that in the two-argument case, `y` is mutated by `f!` during preparation.
-"""
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
+    In the two-argument case, `y` is mutated by `f!` during preparation."""
 function prepare_pushforward end
 
 """

DifferentiationInterface/src/second_order/hessian.jl

@@ -4,6 +4,9 @@
     prepare_hessian(f, backend, x) -> extras
 
 Create an `extras` object subtyping [`HessianExtras`](@ref) that can be given to Hessian operators.
+
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
 """
 function prepare_hessian end
 

DifferentiationInterface/src/second_order/hvp.jl

@@ -4,6 +4,9 @@
     prepare_hvp(f, backend, x, v) -> extras
 
 Create an `extras` object subtyping [`HVPExtras`](@ref) that can be given to Hessian-vector product operators.
+
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
 """
 function prepare_hvp end
 

DifferentiationInterface/src/second_order/second_derivative.jl

@@ -4,6 +4,9 @@
     prepare_second_derivative(f, backend, x) -> extras
 
 Create an `extras` object subtyping [`SecondDerivativeExtras`](@ref) that can be given to second derivative operators.
+
+!!! warning
+    If the function changes in any way, the result of preparation will be invalidated, and you will need to run it again.
 """
 function prepare_second_derivative end