add 071 comptime 6 inline for

1 files changed, 56 insertions, 0 deletions

diff --git a/exercises/071_comptime6.zig b/exercises/071_comptime6.zig
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+++ b/exercises/071_comptime6.zig
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+//
+// There have been several instances where it would have been
+// nice to use loops in our programs, but we couldn't because the
+// things we were trying to do could only be done at compile
+// time. We ended up having to do those things MANUALLY, like
+// NORMAL people. Bah! We are PROGRAMMERS! The computer should be
+// doing this work.
+//
+// An 'inline for' is performed at compile time, allowing you to
+// programatically loop through a series of items in situations
+// like those mentioned above where a regular runtime 'for' loop
+// wouldn't be allowed:
+//
+//     inline for (.{ u8, u16, u32, u64 }) |T| {
+//         print("{} ", .{@typeInfo(T).Int.bits});
+//     }
+//
+// In the above example, we're looping over a list of types,
+// which are available only at compile time.
+//
+const print = @import("std").debug.print;
+
+// Remember Narcissus from exercise 065 where we used builtins
+// for reflection? He's back and loving it.
+const Narcissus = struct {
+    me: *Narcissus = undefined,
+    myself: *Narcissus = undefined,
+    echo: void = undefined,
+};
+
+pub fn main() void {
+    var narcissus: Narcissus = Narcissus {};
+
+    print("Narcissus has room in his heart for:", .{});
+
+    // Last time we examined the Narcissus struct, we had to
+    // manually access each of the three fields. Our 'if'
+    // statement was repeated three times almost verbatim. Yuck!
+    //
+    // Please use an 'inline for' to implement the block below
+    // for each field in the slice 'fields'!
+
+    const fields = @typeInfo(Narcissus).Struct.fields;
+
+    ??? {
+        if (field.field_type != void) {
+            print(" {s}", .{field.name});
+        }
+    }
+
+    // Once you've got that, go back and take a look at exercise
+    // 065 and compare what you've written to the abomination we
+    // had there!
+
+    print(".\n", .{});
+}