Re: echo: -n, the next installment
On Saturday, 27 July 2013 at 01:09:03 UTC, Jesse Phillips wrote: On Friday, 26 July 2013 at 00:38:46 UTC, John Colvin wrote: After a few weeks of not getting around to it, here's my second post: http://foreach-hour-life.blogspot.co.uk/2013/07/the-first-corner-n-for-echo.html BTW, std.getopt is a good way to parse arguments. Not sure if it is relevant to what you want to teach, but should generally be preferred over handwritten. I'm pretty sure it wouldn't work ideally for echo as the behaviour depends on the order of the arguments.
Re: echo: -n, the next installment
On Saturday, 27 July 2013 at 12:19:44 UTC, John Colvin wrote: I'm pretty sure it wouldn't work ideally for echo as the behaviour depends on the order of the arguments. It also has some odd little niggles -- e.g. it's not nice that with a short option you can have --t 5 and --t=5 but not -t 5 or -t=5 (according to docs you can only use -t5 ).
Re: echo: -n, the next installment
On Saturday, 27 July 2013 at 12:39:24 UTC, monarch_dodra wrote:
On Friday, 26 July 2013 at 00:38:46 UTC, John Colvin wrote:
After a few weeks of not getting around to it, here's my
second post:
http://foreach-hour-life.blogspot.co.uk/2013/07/the-first-corner-n-for-echo.html
I tried to post a comment on your blog, but I failed. Anyways,
I wanted to post:
And here is the second comment I wanted to put:
When parsing the options, you use an if-else. I don't know if its
just me, but I find that using a switch is clearer (it's what you
do in your second example). It also introduces string cases
(illegal in C++), and labeled control statements.
The code becomes:
import std.stdio : writef, writeln;
void main(string[] args)
{
assert(args.length);
args = args[1 .. $];
bool writeNewline = true;
size_t i = 0;
myForeach: foreach(arg; args)
{
switch(arg)
{
case -n:
writeNewline = false;
++i;
break;
default:
break myForeach;
}
}
args = args[i .. $];
writef(%-(%s %), args);
if(writeNewline)
writeln();
}
PS: If I figure out how to comment on your blog, I'll paste the
comments there :)
Re: echo: -n, the next installment
On Saturday, 27 July 2013 at 12:19:44 UTC, John Colvin wrote: On Saturday, 27 July 2013 at 01:09:03 UTC, Jesse Phillips wrote: On Friday, 26 July 2013 at 00:38:46 UTC, John Colvin wrote: After a few weeks of not getting around to it, here's my second post: http://foreach-hour-life.blogspot.co.uk/2013/07/the-first-corner-n-for-echo.html BTW, std.getopt is a good way to parse arguments. Not sure if it is relevant to what you want to teach, but should generally be preferred over handwritten. I'm pretty sure it wouldn't work ideally for echo as the behaviour depends on the order of the arguments. getopt knows how to handle ordering, it's really just a matter of echo's argument parsing rules being different from classic getopt. For example, echo does not handle -- argument (end of options mark), which means it is literally impossible for echo's first string argument to be -n. So for example, while echo -- -n would print -- -n, a getopt echo would print -n. Arguably, this is better behavior, but if the goal is exact replication, then it's wrong :/
Re: echo: -n, the next installment
On Saturday, 27 July 2013 at 12:52:11 UTC, monarch_dodra wrote:
And here is the second comment I wanted to put:
When parsing the options, you use an if-else. I don't know if
its just me, but I find that using a switch is clearer (it's
what you do in your second example). It also introduces string
cases (illegal in C++), and labeled control statements.
The code becomes:
import std.stdio : writef, writeln;
void main(string[] args)
{
assert(args.length);
args = args[1 .. $];
bool writeNewline = true;
size_t i = 0;
myForeach: foreach(arg; args)
{
switch(arg)
{
case -n:
writeNewline = false;
++i;
break;
default:
break myForeach;
}
}
args = args[i .. $];
writef(%-(%s %), args);
if(writeNewline)
writeln();
}
PS: If I figure out how to comment on your blog, I'll paste the
comments there :)
thanks for the info on writef, I didn't realise it could do that.
About the switch statement: I didn't even know you could do that
with labels, I'd only ever used them for gotos. I'll consider
putting that in the next version.
Re: echo: -n, the next installment
On Friday, 26 July 2013 at 00:38:46 UTC, John Colvin wrote: After a few weeks of not getting around to it, here's my second post: http://foreach-hour-life.blogspot.co.uk/2013/07/the-first-corner-n-for-echo.html BTW, std.getopt is a good way to parse arguments. Not sure if it is relevant to what you want to teach, but should generally be preferred over handwritten.
echo: -n, the next installment
After a few weeks of not getting around to it, here's my second post: http://foreach-hour-life.blogspot.co.uk/2013/07/the-first-corner-n-for-echo.html
