ploticus: Modernize

- Split pname & version.
- Format the expression.
- Do not use custom builder, the generic one is good enough.
- Install the man pages to datadir instead of $out, where they would be moved anyway.
– Allowing us to drop the postFixup.
- Use patch instead of wrapper for pointing to prefabs. This is what Debian does and it will also apply to the pl binary, not just the ploticus alias.
- Since the wrapping is no longer necessary, let’s create the alias using a symlink.

pkgs/tools/graphics/ploticus/builder.sh

···
-source $stdenv/setup
-
-preBuild() {
-  cd src
-}
-
-preInstall() {
-  mkdir -p $out/bin
-}
-
-postInstall() {
-  # Install the "prefabs".
-  mkdir -p $out/share/ploticus/prefabs &&		\
-  cd .. &&						\
-  cp -rv prefabs/* $out/share/ploticus/prefabs
-
-  # Create a wrapper that knows where to find them.  Debian's package
-  # does something similar by patching directly the C file that looks
-  # for `$PLOTICUS_PREFABS'.
-  cat > $out/bin/ploticus <<EOF
-#! $SHELL -e
-PLOTICUS_PREFABS="$out/share/ploticus/prefabs"
-export PLOTICUS_PREFABS
-exec "$out/bin/pl" \$@
-EOF
-  chmod +x $out/bin/ploticus
-
-  # Install the man pages.
-  cp -rv man $out
-  ln -s "$out/man/man1/pl.1" "$out/man/man1/ploticus.1"
-}
-
-genericBuild

pkgs/tools/graphics/ploticus/default.nix

···
-{lib, stdenv, fetchurl, zlib, libX11, libpng}:
+{ lib
+, stdenv
+, fetchurl
+, zlib
+, libX11
+, libpng
+}:
 
 stdenv.mkDerivation {
-  name = "ploticus-2.42";
+  pname = "ploticus";
+  version = "2.42";
 
-  builder = ./builder.sh;
   src = fetchurl {
     url = "mirror://sourceforge/ploticus/ploticus/2.41/pl241src.tar.gz";
     sha256 = "1065r0nizjixi9sxxfxrnwg10r458i6fgsd23nrxa200rypvdk7c";
   };
 
-  buildInputs = [ zlib libX11 libpng ];
+  patches = [
+    # Replace hardcoded FHS path with $out.
+    ./ploticus-install.patch
+
+    # Set the location of the PREFABS directory.
+    ./set-prefabs-dir.patch
+  ];
+
+  buildInputs = [
+    zlib
+    libX11
+    libpng
+  ];
 
   hardeningDisable = [ "format" ];
 
-  patches = [ ./ploticus-install.patch ];
+  preBuild = ''
+    cd src
+  '';
 
-  # Make the symlink relative instead of absolute.
-  # Otherwise it breaks when auto-moved to $out/share.
-  preFixup = ''
-    ln -sf pl.1 "$out"/man/man1/ploticus.1
+  preInstall = ''
+    mkdir -p "$out/bin"
+  '';
+
+  postInstall = ''
+    cd ..
+
+    # Install the “prefabs”.
+    mkdir -p "$out/share/ploticus/prefabs"
+    cp -rv prefabs/* "$out/share/ploticus/prefabs"
+
+    # Install the man pages.
+    cp -rv man $out/share
+
+    # Add aliases for backwards compatibility.
+    ln -s "pl.1" "$out/share/man/man1/ploticus.1"
+    ln -s "pl" "$out/bin/ploticus"
   '';
 
   meta = with lib; {
     description = "A non-interactive software package for producing plots and charts";
-    longDescription = ''Ploticus is a free, GPL'd, non-interactive
+    longDescription = ''
+      Ploticus is a free, GPL'd, non-interactive
       software package for producing plots, charts, and graphics from
       data.  Ploticus is good for automated or just-in-time graph
       generation, handles date and time data nicely, and has basic
       statistical capabilities.  It allows significant user control
-      over colors, styles, options and details.'';
+      over colors, styles, options and details.
+    '';
     license = licenses.gpl2Plus;
     maintainers = with maintainers; [ pSub ];
     homepage = "http://ploticus.sourceforge.net/";

pkgs/tools/graphics/ploticus/set-prefabs-dir.patch

···
+--- a/src/Makefile
++++ b/src/Makefile
+@@ -133,6 +133,6 @@
+ #### To set a hard-coded directory for prefabs files, uncomment & edit the following..
+ #### If done, users won't be required to have PLOTICUS_PREFABS environment variable defined.
+ #### This option not available for win32
+-# PREFABS_DIR = "/usr/lib/ploticus/prefabs"
++PREFABS_DIR = "$(out)/share/ploticus/prefabs"
+ 
+