From c29511a3cc3f7832b6c1add8b08748d3fa01250c Mon Sep 17 00:00:00 2001
From: Sameer Rahmani <lxsameer@gnu.org>
Date: Mon, 12 Sep 2022 15:24:31 +0100
Subject: [PATCH] Finish up ep 10 on macros

---
 core/fg42/cube.el        |  8 ++++----
 core/fg42/flags.el       | 24 +++++++++++++-----------
 docs/videos.org          | 32 +++++++++++++++++++++++++++++---
 scripts/install_files.sh |  1 +
 4 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/core/fg42/cube.el b/core/fg42/cube.el
index 57976f8..049962c 100644
--- a/core/fg42/cube.el
+++ b/core/fg42/cube.el
@@ -29,12 +29,12 @@
 (require 'fg42/utils)
 
 (defvar fg42/after-cubes-setup-hook nil
-  "A hook that will be run after all the active cubes got setup. This hook
-is dedicated for the codes that needs to do stuff based on other cubes
-presence. With this hook we eliminate the need for cube ordering.
+  "A hook that will be run after all the active cubes got setup.
+This hook is dedicated for the codes that needs to do stuff based on other cubes
+presence.  With this hook we eliminate the need for cube ordering.
 
 It will be called in the `fg42-config' and the proper way to use
-it is to use `fg42/after-cubes' macro. ")
+it is to use `fg42/after-cubes' macro.")
 
 
 (defvar fg42/available-cubes '()
diff --git a/core/fg42/flags.el b/core/fg42/flags.el
index d9813aa..7caf4a2 100644
--- a/core/fg42/flags.el
+++ b/core/fg42/flags.el
@@ -90,9 +90,12 @@ For example, `(fg42/merge-flags (list f1 f2 f3) f4 -f2)' will return `(f1 f3 f4)
 (defmacro defflag (flag-name docstring &optional default-value)
   "Define a new flag FLAG-NAME with the given DOCSTRING.
 If the DEFAULT-VALUE is a non nil value, then the flag will be
-added to the activa flags list."
-  (let ((var-name (intern (format "fg42/-flag-%s" flag-name)))
-        (set-default (if default-value `((add-to-list 'fg42/flags ',flag-name)) ())))
+added to the active flags list."
+  (declare (doc-string 2) (indent defun))
+  (let ((var-name (intern (format "fg42/-flag-%s" (symbol-name flag-name))))
+        (set-default (when default-value
+                       `((add-to-list 'fg42/flags ',flag-name)))))
+
     `(if (boundp ',var-name)
          (warn (format "Flag name `%s' already defined" ,(format "%s" flag-name)))
        (progn
@@ -106,12 +109,11 @@ added to the activa flags list."
   (declare (indent defun))
   ;; The `cube-local-flags' variable here is going to be
   ;; defined in cubes to hold the local flags for each cube
-  (if (and (boundp 'cube-local-flags)
-           (member flag cube-local-flags))
-      `,@body
-    `(if (member ',flag fg42/flags)
-         ,@body
-       nil)))
+  (if (not (and (boundp 'cube-local-flags)
+                (member flag cube-local-flags)))
+      `(progn ,@body)
+    `(when (member ',flag fg42/flags)
+       ,@body)))
 
 
 (defmacro if-flag (flag then else)
@@ -121,8 +123,8 @@ added to the activa flags list."
   ;; defined in cubes to hold the local flags for each cube
   (if (and (boundp 'cube-local-flags)
            (member flag cube-local-flags))
-      `,@then
-    `(if (member ',flag fg42/flags)
+      then
+     `(if (member ',flag fg42/flags)
          ,then
        ,else)))
 
diff --git a/docs/videos.org b/docs/videos.org
index 92a193e..dbf2b65 100644
--- a/docs/videos.org
+++ b/docs/videos.org
@@ -556,7 +556,8 @@ A collection of handy functions that operate on ~sequences~.
 
 #+END_SRC
 - ~seq-min~, ~seq-max~
-* Episode 9 - Introduction to Macros
+* DONE Episode 9 - Introduction to Macros
+CLOSED: [2022-09-11 Sun 11:08]
 ** What is a macro?
 - A macro is defined much like a function
 - It works on compile time
@@ -598,7 +599,32 @@ A collection of handy functions that operate on ~sequences~.
 - [[https://twitter.com/lxsameer][@lxsameer]] on Twitter
 
 * Episode 10 - More on Macros
-** Quasiquotes aka back quote
+** Quasiquote aka backquote (`)
+- Backquote constructs allow us to quote an expression, but selectively evaluate sub-expressions
+- Similar to a template engine for lisp expressions
+- It can be used on its own but it will shine in macro definitions
+- On the simplest form it is identical to ~quote~
+- Special markers ~,~ and ~,@~ can be used to mark expressions for evaluation
+- ~,~ will replace the return value of the evaluation with the expression
+- ~,@~ will replace and splice the return value of the evaluation
+*** Examples
+
+#+BEGIN_SRC emacs-lisp
+  `3
+  `(1 2 3 4)
+  `(1 2 3 ,(+ 5 6))
+  `(1 2 3 ,(list 4 5 6))
+  `(1 2 3 ,@(list 4 5 6))
+
+  `(setq ,(intern (upcase "some_var")) 3)
+#+END_SRC
+
 ** ~declare~ form
+- It's a special macro which can be used to add meta properties to a function or macro
+  + ~doc-string~
+  + ~indent~
+
+** Real Examples
+Let's discuss ~defflag~ and ~when-flag~ macros in [[file:../core/fg42/flags.el]]
+
 * Episode 11 - Common pitfalls of Macros
-*
diff --git a/scripts/install_files.sh b/scripts/install_files.sh
index 28d5187..2d9faa2 100644
--- a/scripts/install_files.sh
+++ b/scripts/install_files.sh
@@ -75,6 +75,7 @@ install_runners() {
 
     info "Copying share files..."
     sudo mkdir -p /usr/share/fg42/
+    sudo mkdir -p /usr/local/share/applications
     sudo cp $fg42_home/share/applications/fg42.desktop /usr/local/share/applications
     sudo cp -r $fg42_home/share/icons/hicolor/ /usr/local/share/icons
     sudo cp -r $fg42_home/share/* /usr/share/fg42/