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From: Kaz Kylheku <643-408-1753@kylheku.com>
Newsgroups: comp.lang.c
Subject: Re: C23 thoughts and opinions
Date: Fri, 31 May 2024 15:34:29 -0000 (UTC)
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Message-ID: <20240531081143.419@kylheku.com>
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On 2024-05-31, bart <bc@freeuk.com> wrote:
> Here's how builtin embedding worked using a feature of my older C compiler:
>
>    #include <stdio.h>
>    #include <string.h>
>
>    char hello[] = strinclude("hello.c");
>
>    int main(void) {
>        printf("hello =\n%s\n", hello);
>        printf("strlen(hello) = %zu\n", strlen(hello));
>        printf("sizeof(hello) = %zu\n", sizeof(hello));
>    }

Lisp:

$ cat strincl.tl
(defmacro strinclude (path)
  (put-line `including @path`)
  (file-get-string path))

(defun test()
  (strinclude "/etc/hostname"))

When we run it interpreted we see from the debug put-line that /etc/hostname is
included at macro-expansion time before we run the test function:

$ txr -i strincl.tl
including /etc/hostname
This TTY may be recorded for privacy-violating and evidence-gathering purposes.
1> (test)
"sun-go\n"

Now compile the file: the file is pulled it at compile time. Twice. :)
A double expansion took place due to certain complexities of compiling.

$ txr --compile=strincl.tl
including /etc/hostname
including /etc/hostname

Now when we load the compiled file, the diagnostic trace
"including /etc/hostname" no longer appears: the string is part of the test
function as a literal:

$ txr -i strincl
TXR is enteric coated to release over 24 hours of lasting relief.
1> (test)
"sun-go\n"

-- 
TXR Programming Language: http://nongnu.org/txr
Cygnal: Cygwin Native Application Library: http://kylheku.com/cygnal
Mastodon: @Kazinator@mstdn.ca