#!/bin/bash
set -euo pipefail
-# Provides RT_CPP_FILES
+# Provides RT_CPP_FILES and paths
source "$(dirname "$0")/environment.sh"
+# Check required env vars
if [[ -z "${ROOT:-}" ]]; then
echo "❌ ROOT environment variable is not set. Aborting."
exit 1
exit 1
fi
+# Choose files to diff
+FILES=()
+if [[ "$#" -gt 0 ]]; then
+ FILES=("$@")
+else
+ FILES=("${RT_CPP_FILES[@]}")
+fi
+
echo "🔍 Diffing library ↔ libcpp..."
-for file in "${RT_CPP_FILES[@]}"; do
+for file in "${FILES[@]}"; do
SRC="$SRCDIR/$file"
DEST="$DESTDIR/$file"
* cpp_ext
-These cpp_ext files are not used in the code for RT_gcc. Nor do they use RT extensions. Rather developing them was part of the due diligence before electing to write the RT extensions.
-
-I find cpp_ext_0 to be useful, and would not hesitate to use it in production code.
-
-In contrast, was a good pedagogical tool for learning cpp, but I would hesitate to use it in production code. The reasoning being that recursion can lead to compiler error messages that span pages.
+The cpp_ext.c files will work with gcc without the RT extensions. With the RT extensions they are deprecated.
** cpp_ext_0
** cpp_ext_1
+This is an example of what not to do with production code. This is not part of the RT extensions.
+
+However, cpp_ext_1 is wonderful way to learn more about cpp. It tricks cpp into doing limited depth recursion despite its macro painting feature.
+
+It did make it into some of my C code for implementing variadic CAT before it was available without recursion with the RT extensions.
+
I pulled the original version from Jonathan Heathcote's "cpp magic", http://jhnet.co.uk/articles/cpp_magic, and modified it to work with the non-existence is false logic. Open AI suggests additional contributors to cpp trickery:
Paul F. Dubois — wrote about C macro tricks in early numerical computing contexts.
The Boost Preprocessor Library (by Paul Mensonides and others) contains some of the most extensive and formalized C macro "magic" ever crafted.
-I don't use cpp_ext_1 in production code because it can lead to very long error messages when compiling, and I have found non-recursive approaches for what I need. See the top level document/ directory for more discussion on cpp techniques (yet to come ;-).
+Using cpp_ext_1 can result in very long error messages when compiling. Get some popcorn, and have fun watching them scroll by.
* cpp_ext_rt
-In cpp_ext_0 it was not possible to write a routine that adds a member to a set, because we cannot create macro names on the fly. The `#assign` directive in the rt extension solves this problem.
+In cpp_ext_0 it was not possible to write a routine that adds a member to a set, because cpp had no facilitate for auto-generating macro names. The `#assign` directive in the rt extension solves this problem.
+
+CAT is an often used macro for prefixing a namespace, prefixing a set name to the front of an identifier before a membership test, or creating identifiers for equality matching. Seldom do we need very many arguments for these use case, though the exact number is not always bounded.
-Cat is an often used macro for prefixing a namespace, prefixing a set name to the front of an identifier before a membership test, or creating identifiers for equality matching. Seldom do we need very many levels of concatenation, though the exact number is not always bounded. Currently I use cpp_ext_1 recursion for variadic concatenation so that CAT won't have a number, CAT2, CAT3, etc. Variadic CAT seems like a reasonable thing to be able to do perhaps by putting ## in front of __VA_ARGS__. Hence, I added the built in macro __CAT(SEP, ...).
+Variadic CAT seems like a reasonable thing to be able to do. One might imagine putting ## in front of __VA_ARGS__; though it would be nice to also have an optional separator. Hence, I added the built in macro RT_CAT(SEP, ...).
projects / RT-gcc / commitdiff