Re: override toString() for a tuple?
On Wed, 04 Jun 2014 05:35:18 + Steve D via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: Is it possible to override std tuple's toString format? so that auto a = tuple(hello,1,2,3); writeln(a); prints (hello, 1, 2, 3) and not Tuple!(string, int, int, int)(hello, 1, 2, 3) I'm aware I could write a custom formatter function, but it would be nice not to have to use such a function for every tuple printed by the program. Overriding toString() one time in program (if possible) would give the ideal default behaviour. (I would duplicate the current typecons.d toString() and strip off the prefix) thanks for any help toString is a member of Tuple, and there's no way to override that externally. You could create a wrapper struct for a Tuple whose toString method did what you want, and you could just create a function which generated the string that you wanted that you used whenever printing out a Tuple, but there is no way to globally override Tuple's toString. The closest that you could do to overriding Tuple's toString in one place would be to write your own wrappers for whatever printing functions you want to use, have them detect when they're given a Tuple, and then print them the way that you want and pass everything else directly on to writeln or whatever it is you're wrapping. Then, the print functions would take care of it for you, but writing such a function wouldn't exactly be fun. If you're really determined to print tuples differently, you _could_ simply copy std.typecons.Tuple to your own code and alter it to do what you want. - Jonathan M Davis
Re: override toString() for a tuple?
On Wednesday, 4 June 2014 at 06:04:22 UTC, Jonathan M Davis via Digitalmars-d-learn wrote: toString is a member of Tuple, and there's no way to override that externally. ... Hi Jonathan, Yeah, I'll probably just keep my locally cobbled version of typecons.d in my path. The other options would be hard going as I've got tuples printed from arrays and variant arrays etc as well as individually. It's just easier to hack the default library code, although not so elegant. You would think the promise of OO and Inheritance would make it easy and free us from hacks like this ;) That said, it's only a personal project so as long as it works, who cares? Many Thanks for your reply Steve D
Re: why it said no identifier for declarator …
On Wednesday, 4 June 2014 at 00:07:35 UTC, Jesse Phillips wrote: On Tuesday, 3 June 2014 at 22:10:06 UTC, bioinfornatics wrote: I do not see why it fail in debug output we see that tuple have a field with given name. Your generated output (short and formatted) alias TL = Tuple!(int,x, bool function( const ref string ), xStartsWith , bool function( const ref string ), xEndsWith , int,y, bool function( const ref string ), yStartsWith , bool function( const ref string ), yEndsWith ); TL.xStartsWith... TL is a type. TL variable; variable.xStartsWith... oh stupid me thanks Jesse sometime you do not see a problem visible as the nose on your face.
Re: override toString() for a tuple?
On Wed, 04 Jun 2014 06:25:53 + Steve D via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: You would think the promise of OO and Inheritance would make it easy and free us from hacks like this ;) That would require using OO and inheritance, which has nothing to do with Tuple. ;) And actually, I find that I very rarely need inheritance. It's definitely the right solution for some problems, but in the vast majority of cases, I find that structs are a better solution - especially because they're far more composable. OO is actually very bad for code reuse, because it's not particularly composable at all. - Jonathan M Davis
Re: why it said no identifier for declarator …
On Wednesday, 4 June 2014 at 00:07:35 UTC, Jesse Phillips wrote:
On Tuesday, 3 June 2014 at 22:10:06 UTC, bioinfornatics wrote:
I do not see why it fail in debug output we see that tuple
have a
field with given name.
Your generated output (short and formatted)
alias TL = Tuple!(int,x, bool function( const ref string
),
xStartsWith , bool function( const ref string ), xEndsWith ,
int,y, bool function( const ref string ), yStartsWith ,
bool
function( const ref string ), yEndsWith );
TL.xStartsWith...
TL is a type.
TL variable;
variable.xStartsWith...
after a tmeplate update
template toTuple(T){
static string maker(){
string assignFunction = TL tl; ;
string statement = alias TL = Tuple!(;
foreach(const memberName; __traits(allMembers, T)){
mixin(`alias f = Filter!(isSection,
__traits(getAttributes, T.` ~ memberName ~ `));`);
if( f.length == 1 )
{
statement ~= typeof(__traits(getMember, T,
memberName)).stringof ~ ,\ ~ memberName ~ \,
~ bool function( const ref string
), \ ~ memberName ~ StartsWith\,
~ bool function( const ref string
), \ ~ memberName ~ EndsWith\, ;
assignFunction ~= tl. ~ memberName ~
StartsWith = __traits(getAttributes, T. ~ memberName ~
)[0].startsWith;
~ tl. ~ memberName ~ EndsWith
= __traits(getAttributes, T. ~ memberName ~ )[0].endsWith; ;
}
}
statement = statement[0..$-2] ~ ) ; ; // $-2 to remove
extra comma
return statement~assignFunction~ alias toTuple = tl;;
}
pragma( msg, maker() );
mixin( maker() );
}
which generate this string:
alias TL = Tuple!(int,x, bool function( const ref string ),
xStartsWith, bool function( const ref string ), xEndsWith,
int,y, bool function( const ref string ), yStartsWith, bool
function( const ref string ), yEndsWith) ;
TL tl;
tl.xStartsWith = __traits(getAttributes, T.x)[0].startsWith;
tl.xEndsWith = __traits(getAttributes, T.x)[0].endsWith;
tl.yStartsWith = __traits(getAttributes, T.y)[0].startsWith;
tl.yEndsWith = __traits(getAttributes, T.y)[0].endsWith;
alias toTuple = tl;
This produce an error at mixin step:
attribute.d-mixin-62(62): Error: no identifier for declarator
tl.xStartsWith
attribute.d-mixin-62(62): Error: Declaration expected, not '='
attribute.d-mixin-62(62): Error: no identifier for declarator
tl.xEndsWith
attribute.d-mixin-62(62): Error: Declaration expected, not '='
attribute.d-mixin-62(62): Error: no identifier for declarator
tl.yStartsWith
attribute.d-mixin-62(62): Error: Declaration expected, not '='
attribute.d-mixin-62(62): Error: no identifier for declarator
tl.yEndsWith
attribute.d-mixin-62(62): Error: Declaration expected, not '='
;
Re: Building 32bit program with MSVC?
LLVM never supported OMF. LDC uses msvcrt runtime, and MS claims that whatever can link with msvcrt, it also can link with later versions of msvcrt.
Re: Kernel in D
On Saturday, 31 May 2014 at 23:27:45 UTC, Qox wrote: On Saturday, 31 May 2014 at 07:57:18 UTC, Kagamin wrote: http://www.xomb.org/ ? seems to be outdated, but its another OS written in D. It's dead for only a year, the developer have probably graduated.
Re: why it said no identifier for declarator …
I take it the output looks something like this:
struct S {
int a;
}
S s;
s.a = 3;
void main() {
}
Hope this clears up this next problem. Module scope doesn't get
to utilize a variable, it can only initialize at compile-time.
Arrays as template parameters
I have the following code (on dpaste,
http://dpaste.dzfl.pl/636c04430a33):
enum : uint { a, b, c }
enum list = [a, b];
void foo(T...)()
{
pragma(msg, T[0].length); // fine
pragma(msg, T[0][0]); // fine
pragma(msg, T[0][1]); // fine
foreach(i; Iota!(0,T[0].length)) // fine
pragma(msg, T[0][i]);
//foreach(c; T[0]) // not fine
//pragma(msg, c);
}
template Iota(size_t i, size_t n)
{
import std.typetuple : TypeTuple;
static if (n == 0) alias TypeTuple!() Iota;
else alias TypeTuple!(i, Iota!(i + 1, n - 1)) Iota;
}
void main()
{
foo!list;
}
Just trying to pass a statically known array as a template
parameter. The foreach marked 'not fine' doesn't work, saying c
cannot be read at compile time, despite the length and all values
being known at compile time. The foreach above it uses a template
to generate a static tuple of indices, which are used to index
into the array, which works but seems unnecessary.
Is there a better way to do this?
how to get line number after readln
I've got a program that reads a text file line by line (using std.stdio readln()) and I'd like to refer to the line number when I send a message to stderr upon finding a mis-formatted line. Is there a way to get the current line number? Of course, I could create a counter and increment it with each call to readln, but is there a cool way of doing this? Okay, call me lazy... just don't call me late for dinner! :-) Robert
Re: how to get line number after readln
On 06/04/2014 05:05 PM, Robert Hathaway wrote:
I've got a program that reads a text file line by line (using std.stdio
readln())
Consider using byLine() instead. (Important: byLine uses an internal
buffer for the line; so, don't forget to make a copy if you want to
store the line for later use.)
and I'd like to refer to the line number when I send a message
to stderr upon finding a mis-formatted line. Is there a way to get the
current line number? Of course, I could create a counter and increment
it with each call to readln, but is there a cool way of doing this?
Okay, call me lazy... just don't call me late for dinner! :-)
Robert
One cool way is a zipped sequence:
import std.stdio;
import std.range;
void main()
{
foreach (i, line; zip(sequence!n, File(deneme.txt).byLine)) {
writefln(%s: %s, i, line);
}
}
Ali
Re: how to get line number after readln
On Thursday, 5 June 2014 at 00:33:26 UTC, Ali Çehreli wrote:
On 06/04/2014 05:05 PM, Robert Hathaway wrote:
I've got a program that reads a text file line by line (using
std.stdio
readln())
Consider using byLine() instead. (Important: byLine uses an
internal buffer for the line; so, don't forget to make a copy
if you want to store the line for later use.)
and I'd like to refer to the line number when I send a message
to stderr upon finding a mis-formatted line. Is there a way
to get the
current line number? Of course, I could create a counter and
increment
it with each call to readln, but is there a cool way of
doing this?
Okay, call me lazy... just don't call me late for dinner! :-)
Robert
One cool way is a zipped sequence:
import std.stdio;
import std.range;
void main()
{
foreach (i, line; zip(sequence!n,
File(deneme.txt).byLine)) {
writefln(%s: %s, i, line);
}
}
Ali
Once this[1] gets merged you'll be able to do this:
foreach (lineNum, line; File(deneme.txt).byLine().enumerate(1))
writefln(%s: %s, lineNum, line);
Which is a bit more clear about the intent.
1. https://github.com/D-Programming-Language/phobos/pull/1866
