From 11a856fbb3cacc1d72c46ae639a81c8b51cdf4c4 Mon Sep 17 00:00:00 2001
From: Graham A Smith <grahamas@gmail.com>
Date: Wed, 31 Jan 2018 13:12:32 -0600
Subject: [PATCH] Allow animation frame saving frequency to be a variable.

---
 src/animation.jl | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/animation.jl b/src/animation.jl
index 93f28427..12fdb36b 100644
--- a/src/animation.jl
+++ b/src/animation.jl
@@ -115,6 +115,7 @@ function _animate(forloop::Expr, args...; callgif = false)
   # add the call to frame to the end of each iteration
   animsym = gensym("anim")
   countersym = gensym("counter")
+  freqassert = :()
   block = forloop.args[2]
 
   # create filter
@@ -127,7 +128,7 @@ function _animate(forloop::Expr, args...; callgif = false)
     # filter every `freq` frames (starting with the first frame)
     @assert n == 2
     freq = args[2]
-    @assert isa(freq, Integer) && freq > 0
+    freqassert = :(@assert isa($freq, Integer) && $freq > 0)
     :(mod1($countersym, $freq) == 1)
 
   elseif args[1] == :when
@@ -147,6 +148,7 @@ function _animate(forloop::Expr, args...; callgif = false)
 
   # full expression:
   esc(quote
+    $freqassert             # if filtering, check frequency is an Integer > 0
     $animsym = Animation()  # init animation object
     $countersym = 1         # init iteration counter
     $forloop                # for loop, saving a frame after each iteration