digitalmars.D - toString not working...

Orgoton <orgoton mindless.com> Jan 15 2007

Johan Granberg <lijat.meREM OVE.gmail.com> Jan 15 2007

Orgoton <orgoton mindless.com> Jan 15 2007

Marcin Kuszczak <aarti interia.pl> Jan 15 2007

Ary Manzana <ary esperanto.org.ar> Jan 16 2007

Daniel Keep <daniel.keep+lists gmail.com> Jan 16 2007

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> Jan 16 2007

Leopold Walkling <leopold_walkling web.de> Jan 16 2007
Daniel Giddings <dgiddings bigworldtech.com> Jan 16 2007

Daniel Giddings <dgiddings bigworldtech.com> Jan 16 2007

Orgoton <orgoton mindless.com> writes:

I have

ushort number=1092;
char[] text="Some text " ~ number.toString();

it doesn't compile because presumably ushort has no property called "toString"
yet on digitalmars.com/d it says that toString is defined on class "object"
and every type inherits from this object. Any ideas?

Jan 15 2007

Johan Granberg <lijat.meREM OVE.gmail.com> writes:

Orgoton wrote:

 I have
 
 ushort number=1092;
 char[] text="Some text " ~ number.toString();
 
 it doesn't compile because presumably ushort has no property called
 "toString" yet on digitalmars.com/d it says that toString is defined on
 class "object" and every type inherits from this object. Any ideas?


Every type does not inherit from object, every class does. As ushort is not
a class it has no such property. try this code instead;

import std.string;
toString(number);

Jan 15 2007

Orgoton <orgoton mindless.com> writes:

Ok, now I did

import std.string;
ushort number=1092;
char[] text="Some text " ~ toString(number);

and the compiler claimed that the number of arguments of
Object.object.toString()
did not match... So, I did

char[] text="Some text " ~ std.string.toString(number);

and it worked fine. Is this a compiler bug? I did not import object (as it is
implicitly done). Or have I some weird compiler configuration?

Jan 15 2007

Marcin Kuszczak <aarti interia.pl> writes:

Orgoton wrote:

 Ok, now I did
 
 import std.string;
 ushort number=1092;
 char[] text="Some text " ~ toString(number);
 
 and the compiler claimed that the number of arguments of
 Object.object.toString() did not match... So, I did
 
 char[] text="Some text " ~ std.string.toString(number);
 
 and it worked fine. Is this a compiler bug? I did not import object (as it
 is implicitly done). Or have I some weird compiler configuration?


Probably you did:
char[] text="Some text " ~ toString(number);

in class method, so compiler thought you want to refer to Object's
toString() method.

You should escape current scope of class with '.' (dot).
class Test {
        void method(int number) {
                char[] text="Some text " ~ .toString(number);
        }
}

Above code should work.

-- 
Regards
Marcin Kuszczak (Aarti_pl)
-------------------------------------
Ask me why I believe in Jesus - http://zapytaj.dlajezusa.pl (en/pl)
Doost (port of few Boost libraries) - http://www.dsource.org/projects/doost/
-------------------------------------

Jan 15 2007

Ary Manzana <ary esperanto.org.ar> writes:

Marcin Kuszczak escribi�:
 Orgoton wrote:
 
 Ok, now I did

 import std.string;
 ushort number=1092;
 char[] text="Some text " ~ toString(number);

 and the compiler claimed that the number of arguments of
 Object.object.toString() did not match... So, I did

 char[] text="Some text " ~ std.string.toString(number);

 and it worked fine. Is this a compiler bug? I did not import object (as it
 is implicitly done). Or have I some weird compiler configuration?


 Probably you did:
 char[] text="Some text " ~ toString(number);
 
 in class method, so compiler thought you want to refer to Object's
 toString() method.
 
 You should escape current scope of class with '.' (dot).
 class Test {
         void method(int number) {
                 char[] text="Some text " ~ .toString(number);
         }
 }
 
 Above code should work.
 


That's not very intuitive :-(

Can't this be fixed? toString methods should be easy to work since they 
are widely used.

Jan 16 2007

Daniel Keep <daniel.keep+lists gmail.com> writes:

Ary Manzana wrote:
 That's not very intuitive :-(
 
 Can't this be fixed? toString methods should be easy to work since they 
 are widely used.


I can think of two ways:

1) Allow for type extensions, or
2) require the use of "this" in front of all members -- hey, it works 
for Python! :3

The problem here is that if called from an object instance, 
"this.toString" shadows any global "toString"s.  It's not so much a bug 
as a consequence of how D's lookup rules work.  Personally, I think #1 
above is the best long-term solution to this, as it allows you to more 
obviously disambiguate what you're trying to say.

	-- Daniel

Jan 16 2007

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Daniel Keep wrote:
 Ary Manzana wrote:
 That's not very intuitive :-(

 Can't this be fixed? toString methods should be easy to work since 
 they are widely used.


 I can think of two ways:
 
 1) Allow for type extensions, or


 as a consequence of how D's lookup rules work.  Personally, I think #1 
 above is the best long-term solution to this, as it allows you to more 
 obviously disambiguate what you're trying to say.


I agree that would be a nice thing to have. And it can't really be that 
hard to implement; it's already done for arrays, why not for other types?

Jan 16 2007

Leopold Walkling <leopold_walkling web.de> writes:

Hello Marcin,

 Orgoton wrote:
 
 Ok, now I did
 
 import std.string;
 ushort number=1092;
 char[] text="Some text " ~ toString(number);
 and the compiler claimed that the number of arguments of
 Object.object.toString() did not match... So, I did
 
 char[] text="Some text " ~ std.string.toString(number);
 
 and it worked fine. Is this a compiler bug? I did not import object
 (as it is implicitly done). Or have I some weird compiler
 configuration?
 


 char[] text="Some text " ~ toString(number);
 in class method, so compiler thought you want to refer to Object's
 toString() method.
 
 You should escape current scope of class with '.' (dot).
 class Test {
 void method(int number) {
 char[] text="Some text " ~ .toString(number);
 }
 }
 Above code should work.
 



This problem only occurs if you import specific modules (std.thread). So 
if you comment out that line, you can use toString without the dot, this 
isn't the wanted behavior, right?

Jan 16 2007

Daniel Giddings <dgiddings bigworldtech.com> writes:

I've found use of format better in many cases as with tuple's the 
compiler can get confused as to which toString variant to use (giving a 
link error because its trying to compile a call in to toString(bool) on 
a char[]), and it happily avoids any naming conflicts with the toString 
of your class.

class Test {
         void method(int number) {
                 char[] text="Some text " ~ format(number);
         }
}

Marcin Kuszczak wrote:
 Orgoton wrote:
 
 Ok, now I did

 import std.string;
 ushort number=1092;
 char[] text="Some text " ~ toString(number);

 and the compiler claimed that the number of arguments of
 Object.object.toString() did not match... So, I did

 char[] text="Some text " ~ std.string.toString(number);

 and it worked fine. Is this a compiler bug? I did not import object (as it
 is implicitly done). Or have I some weird compiler configuration?


 Probably you did:
 char[] text="Some text " ~ toString(number);
 
 in class method, so compiler thought you want to refer to Object's
 toString() method.
 
 You should escape current scope of class with '.' (dot).
 class Test {
         void method(int number) {
                 char[] text="Some text " ~ .toString(number);
         }
 }
 
 Above code should work.

Jan 16 2007

Daniel Giddings <dgiddings bigworldtech.com> writes:

I suppose I should give an example of the matching error:

import std.stdio;
import std.string;

struct S(T...)
{
	static assert( T.length > 0 );
	
	T fields;
	
	char[] toString()
	{
		char[] result = "(" ~ .toString(fields[0]);
		
		foreach( f; fields[1..$] )
			result ~= "," ~ .toString(f);
		
		return result ~ ")";
	}
}
void main()
{
	S!(char[],double) t;
	
	writefln( t );
}

compiling gives:
t.d(12): function std.string.toString (bool) does not match parameter 
types (char[])
t.d(8): Error: cannot implicitly convert expression 
this._fields_field_0) of type char[] to char*
t.d(22): template instance t.S!(char[],double) error instantiating


but using format:

import std.stdio;
import std.string;

struct S(T...)
{
	static assert( T.length > 0 );
	
	T fields;
	
	char[] toString()
	{
		char[] result = "(" ~ format(fields[0]);
		
		foreach( f; fields[1..$] )
			result ~= "," ~ format(f);
		
		return result ~ ")";
	}
}
void main()
{
	S!(char[],double) t;
	
	writefln( t );
}

compiles, and correctly gives:
(,nan)

Jan 16 2007

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