Hi!
A problem that I came across recently was the difficulty of writing
C++ tutorials for beginners to programming in org mode. In such
tutorials, it would be ideal to keep as much boilerplate away from the
examples so they don't ask questions (until we get to those topics).
The shortest ob-C++ example available is:
#+begin_src C++ :includes <iostream>
std::cout<<"Hello World!\n";
#+end_src
However, it would be nice to add a "using namespace std" to this
source code block, so it can become:
#+BEGIN_SRC C++ :includes <iostream> :namespaces std
cout << "Hello world\n";
#+END_SRC
Which makes it cleaner and easier to read, especially for very short
code snippets, using a bunch of std tools.
Attached are patches for adding a :namespaces export option to C++
blocks, and a patch to documentation on worg that documents this
change.
One concern that I have is that "using namespace *;" is only available
in C++ and not C, but there isn't an easy way I could find to limit
it's usage to only C++ blocks without a bunch of restructuring, so
this will fail if you attempt to set a namespace on a plain C block.
Since it's clear that namespaces aren't part of plain C, I don't think
this is too big of a deal.
Please give this a more thorough review than usual, I'm very new to all of this!
Thanks again for creating/maintaining org mode, it's the greatest!
Also, this contribution puts me very close to the 15 line limit before
I need to get FSF papers signed. I intend to sign papers soon, but I'm
a little busy right now, and I'll get around to submitting the request
later on.
Thanks,
-Jay
PS:
I'm getting an error when I try to run:
#+BEGIN_SRC C :exports output :includes stdio.h
printf("hello world\n");
#+END_SRC
because 'stdio.h' is not surrounded by quotes. I can do <stdio.h> and
have it work fine, but how can I include quotes in the header line?
They seem to be stripped by org, and backslash ecaping them does not
work.
From 1e5fff1741dc853214962b7ea90b0832b4ae3e69 Mon Sep 17 00:00:00 2001
From: Jay Kamat <jaygka...@gmail.com>
Date: Sun, 16 Jul 2017 21:55:24 -0700
Subject: [PATCH] ob-C.el: Add support for specifying namespaces in C/C++
* lisp/ob-C.el (org-babel-C-expand-C): Add a :namespaces export option
to C++ org babel blocks. Namespaces specified here will be added to
the file in the format 'using namespace %s;'. Multiple namespaces
can be specified, separated by spaces.
TINYCHANGE
---
lisp/ob-C.el | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/lisp/ob-C.el b/lisp/ob-C.el
index 2bdda68d5..ba10833d0 100644
--- a/lisp/ob-C.el
+++ b/lisp/ob-C.el
@@ -202,9 +202,15 @@ its header arguments."
(defines (org-babel-read
(or (cdr (assq :defines params))
(org-entry-get nil "defines" t))
- nil)))
+ nil))
+ (namespaces (org-babel-read
+ (or (cdr (assq :namespaces params))
+ (org-entry-get nil "namespaces" t))
+ nil)))
(when (stringp includes)
(setq includes (split-string includes)))
+ (when (stringp namespaces)
+ (setq namespaces (split-string namespaces)))
(when (stringp defines)
(let ((y nil)
(result (list t)))
@@ -224,6 +230,10 @@ its header arguments."
(mapconcat
(lambda (inc) (format "#define %s" inc))
(if (listp defines) defines (list defines)) "\n")
+ ;; namespaces
+ (mapconcat
+ (lambda (inc) (format "using namespace %s;" inc))
+ namespaces "\n")
;; variables
(mapconcat 'org-babel-C-var-to-C vars "\n")
;; table sizes
--
2.11.0
From 3267aeac0b90c76f5091104e13389ce6050dd580 Mon Sep 17 00:00:00 2001
From: Jay Kamat <jaygka...@gmail.com>
Date: Sun, 16 Jul 2017 22:09:06 -0700
Subject: [PATCH] Add documentation for ob-C :namespaces
---
org-contrib/babel/languages/ob-doc-C.org | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/org-contrib/babel/languages/ob-doc-C.org b/org-contrib/babel/languages/ob-doc-C.org
index b1aac99b..faf2b77f 100644
--- a/org-contrib/babel/languages/ob-doc-C.org
+++ b/org-contrib/babel/languages/ob-doc-C.org
@@ -66,7 +66,7 @@ the results of evaluation inserted into the buffer.
: int b=1;
: printf("%d\n", a+b);
: #+end_src
-:
+:
: #+results:
: : 2
@@ -154,6 +154,11 @@ It features:
(C & C++ only) just like =:includes= but for =#defines= lines at the
top of the code.
+- =:namespaces= ::
+ (C++ only)
+ accepts either a single name, or a list of names of namespaces to use.
+ The final format will look like this: =using namespace name;=
+
- =:libs= ::
(C & C++ only) useful for linking with a library, may be given
=-L/path/to/lib= and =-llibrary= instructions.
--
2.11.0
