Re: redirect std out to a string?
On Thursday, 21 May 2020 at 15:42:50 UTC, Basile B. wrote:
On Thursday, 21 May 2020 at 04:29:30 UTC, Kaitlyn Emmons wrote:
is there a way to redirect std out to a string or a buffer
without using a temp file?
yes:
[snip]
Alternatively, setvbuf can be used:
void[1024] buf; // buffer must be valid as long as the program
is running [1]
// (buffer could also be heap-allocated; see
Basile's post)
void main()
{
import std.stdio;
import std.string : fromStringz;
stdout.reopen("/dev/null", "a"); // on Windows, "NUL" should
do the trick
stdout.setvbuf(buf);
writeln("Hello world", 12345);
stdout.writeln("Hello again");
// Lastly, fromStringz is used to get a correctly sized
char[] from the buffer
char[] mystr = fromStringz(cast(char *) buf.ptr);
stderr.writeln("Buffer contents:\n", mystr);
}
[1] https://en.cppreference.com/w/c/io/setvbuf#Notes
Re: redirect std out to a string?
On Thursday, 21 May 2020 at 04:29:30 UTC, Kaitlyn Emmons wrote:
is there a way to redirect std out to a string or a buffer
without using a temp file?
yes:
---
#!dmd -betterC
module runnable;
extern(C) int main()
{
import core.sys.posix.stdio : fclose, stdout, fmemopen,
printf, fflush;
import core.stdc.stdlib : malloc;
char* buff;
enum s = "this will use a buffer from the heap that has, " ~
"just like a file, a FD thanks to fmemopen()";
fclose(stdout);
buff = cast(char*) malloc(4096);
buff[0..4096] = '\0';
stdout = fmemopen(buff, 4096, "wr+");
printf(s);
fflush(stdout);
assert(buff[0..s.length] == s);
return 0;
}
---
something similar should be possible using mmap().
Re: redirect std out to a string?
On Thursday, 21 May 2020 at 04:29:30 UTC, Kaitlyn Emmons wrote: is there a way to redirect std out to a string or a buffer without using a temp file? If you want to do the redirection at startup, it's possible. Have an another program to start your program by std.process functions and redirect stdout to a pipe. The outer program can then handle the output of the inner program however it wishes. Clumsy but possible. But I don't know whether a process can redirect it's own standard input or output.
Re: redirect std out to a string?
On 5/21/20 12:29 AM, Kaitlyn Emmons wrote: is there a way to redirect std out to a string or a buffer without using a temp file? D's I/O is dependent on C's FILE * API, so if you can make that write to a string, then you could do it in D. I don't think there's a way to do it in C. So likely the answer is no. -Steve
redirect std out to a string?
is there a way to redirect std out to a string or a buffer without using a temp file?
