Draft a page about counting arguments

agagniere · Aug 27, 2024 · fadcae4 · fadcae4
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diff --git a/book/pages/05_argcount.md b/book/pages/05_argcount.md
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+# Counting arguments
+
+:::{admonition} Work In Progress
+:class: warning
+This page is a draft
+:::
+
+If you've made it this far, congratulations !
+You've completed the introduction.
+
+We will now start abusing macros and delve into black magic.
+
+The pivotal trick is going to be able to count the number of arguments given to a variadic macro.
+
+:::{preprocessed} 05_first
+:::
diff --git a/book/pages/index.rst b/book/pages/index.rst
@@ -15,4 +15,5 @@ Black Magic
    02_use
    03_log
    04_default
+   05_argcount
    quotes
diff --git a/book/samples/05_first.c b/book/samples/05_first.c
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+#include <stdio.h>
+
+#define ARG_COUNT_1(A, B, C, D, E, F, G, H, I, J, ...) J
+#define ARG_COUNT_2(...) ARG_COUNT_1(__VA_ARGS__ __VA_OPT__(,) 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+
+int main()
+{
+	printf("0: %i\n", ARG_COUNT_2());
+	printf("1: %i\n", ARG_COUNT_2(1));
+	printf("2: %i\n", ARG_COUNT_2(1, 2));
+}
-Original file line number
+Diff line change
@@ Expand Up / @@ -15,4 +15,5 @@ Black Magic @@
 _use
 _log
 _default
+_argcount
        quotes