Move expansions to separate functions

Move expansions to functions and comment them properly there.

setup/mk.sh

@@ -36,29 +36,10 @@ build1() {
     local srcpath dstpath
     srcpath=$1
     dstpath=${srcpath%.skel}
-    perl -pe "
-        s|__FFOO_DIR__|$shrdir|;
-        s|__VERSION__|$(get_version)|;
-    " < $srcpath > $dstpath
+    expand_variables < $srcpath > $dstpath
     if grep -qe '.md$' <<<"$dstpath";
     then
-        perl -we '
-            use strict;
-            my $text;
-            while (<>) {
-                chomp;
-                if (m/<!-- include4: (\S+) -->/) {
-                    open my $fh, $1 or warn "cannot find: $1";
-                    my $text = do { local($/); <$fh> };
-                    close $fh;
-                    $text =~ s/^(.)/    $1/gm;
-                    chomp $text;
-                    print "$text\n";
-                } else {
-                    print "$_\n";
-                }
-            }
-        ' < $srcpath > $dstpath
+        expand_includes < $srcpath > $dstpath
     fi
     echo $dstpath >> built.list
 }
@@ -100,6 +81,41 @@ dist() {
     rm -rf $dirname
 }
 
+expand_includes() {
+    #
+    # Expand include directives
+    #
+    # Expand e.g. `<!-- include4: foo.sh -->` to include code of foo.sh
+    #
+    perl -we '
+        use strict;
+        my $text;
+        while (<>) {
+            chomp;
+            if (m/<!-- include4: (\S+) -->/) {
+                open my $fh, $1 or warn "cannot find: $1";
+                my $text = do { local($/); <$fh> };
+                close $fh;
+                $text =~ s/^(.)/    $1/gm;
+                chomp $text;
+                print "$text\n";
+            } else {
+                print "$_\n";
+            }
+        }
+    '
+}
+
+expand_variables() {
+    #
+    # Expand variable values
+    #
+    perl -pe "
+        s|__FFOO_DIR__|$shrdir|;
+        s|__VERSION__|$(get_version)|;
+    "
+}
+
 install() {
     mkdir -vp $bindir \
               $docdir \