Consider providing a message/warning if fig.alt is not defined?

[TimTaylor]

Would it be worth giving a little nudge via a message / warning if fig.alt is not provided for an image/plot within a document?

[yihui]

I don't know. It's quite simple to implement, but I'm not sure if users would find the messages pesky. I can consider adding an option so users can opt-in to see such messages (e.g., those who do want to get reminded of missing alt text). Thoughts?

diff --git a/R/fuse.R b/R/fuse.R
index a7b9a58..ac4fbb2 100644
--- a/R/fuse.R
+++ b/R/fuse.R
@@ -679,7 +679,6 @@ fuse_code = function(x, blocks) {
   env = opts$fig.env; alt = opts$fig.alt; cap = opts$fig.cap
   att = if (is.null(att <- opts$attr.plot)) '' else paste0('{', att, '}')
   if (is.null(alt)) alt = cap
-  if (is.null(alt)) alt = ''
   p1 = Filter(function(x) !is_plot(x), res)
   p2 = Filter(is_plot, res)
   # get the relative path of the plot directory
@@ -690,6 +689,15 @@ fuse_code = function(x, blocks) {
 
   # recycle alt and attributes for all plots
   pn = length(unlist(p2))
+  if (pn && is.null(alt)) {
+    # reminder about missing alt text if this option is set to TRUE
+    if (getOption('litedown.fig.alt', FALSE)) message(
+      "\nPlease provide a 'fig.alt' option to the code chunk at ", get_loc(lab)
+    )
+    alt = ''
+  }
   alt = rep(alt, length.out = pn)
   att = rep(att, length.out = pn)
   # if figure caption is provided, merge all plots in one env

[TimTaylor]

I like the option approach. It then also makes it very easy for you to switch the default (if there's a desire/need to) in future.

[yihui]

Okay, I just committed the code above. Thanks!