Re: Little demo of allowing basic types to implement interfaces. Was in D.annouce
Just wondering if this exists in the standard library.
I made a function Implements!(T,I) that returns true is a given
type T implements the interface I.
http://dpaste.dzfl.pl/d7a727fd
I've found it really helps with keeping some code clean such as
the below:
void main() {
int i = 0x34342343;
writebytes(i);
}
//enum Order { Big };
//interface IRawBytes { ubyte[] bytes(Order); }
interface IRawBytes { ubyte[] bytes(); }
void writebytes(T)(T item) if (Implements!(T, IRawBytes)) {
import std.stdio : writeln;
writeln(item.bytes);
}
ubyte[] bytes(ref int i) {
ubyte* ptr;
ptr = cast(ubyte*)i;
return ptr[0..i.sizeof];
}
If you decide that IRawBytes.bytes should start taking an Order
parameter you get the same benefits you would have got if you had
used classes with an interface.
Re: Checking if UFCS function exists for a specific type
On Thursday, 29 August 2013 at 21:10:41 UTC, Rory McGuire wrote:
On Thursday, 29 August 2013 at 21:06:04 UTC, Rory McGuire wrote:
Hi all,
I've got this little ctfe template function that checks if a
function called member with first argument T exists. Its for
checking if a type has a custom encoder.
bool hasUFCSmember(T, string member)() {
T v;
// would be nice if we could use ParameterTypeTuple to get
the first arg and check for exact type match
return __traits(compiles, mixin(member ~(v)));
}
forum posted when I hit tab. Meant to ask:
Is there a way to make sure that the compiler is not implicitly
casting T?
Currently it returns true for bool, enum, int etc... even if
the only function available is for an int.
I also have:
template hasUFCSmember(T, string member) {
enum hasUFCSmember = __traits(compiles, mixin(member
~(T.init)));
}
But it doesn't work for types such as string[string] because
T.init is null.
Any help will be greatly appreciated.
Thanks,
R
I suppose I can avoid the implicit casts for function lookup by
using Typedef.
Thanks,
R
Checking if UFCS function exists for a specific type
Hi all,
I've got this little ctfe template function that checks if a
function called member with first argument T exists. Its for
checking if a type has a custom encoder.
bool hasUFCSmember(T, string member)() {
T v;
// would be nice if we could use ParameterTypeTuple to get the
first arg and check for exact type match
return __traits(compiles, mixin(member ~(v)));
}
Re: Checking if UFCS function exists for a specific type
On Thursday, 29 August 2013 at 21:06:04 UTC, Rory McGuire wrote:
Hi all,
I've got this little ctfe template function that checks if a
function called member with first argument T exists. Its for
checking if a type has a custom encoder.
bool hasUFCSmember(T, string member)() {
T v;
// would be nice if we could use ParameterTypeTuple to get the
first arg and check for exact type match
return __traits(compiles, mixin(member ~(v)));
}
forum posted when I hit tab. Meant to ask:
Is there a way to make sure that the compiler is not implicitly
casting T?
Currently it returns true for bool, enum, int etc... even if the
only function available is for an int.
I also have:
template hasUFCSmember(T, string member) {
enum hasUFCSmember = __traits(compiles, mixin(member
~(T.init)));
}
But it doesn't work for types such as string[string] because
T.init is null.
Any help will be greatly appreciated.
Thanks,
R
Re: Using getchar
Its not skipping its looping on a\r\n if you're on windows.
Linux it does the same but only a\n.
Not sure how you'd make it so that you don't have to wait for the
return press. Probably has something to do with console settings,
which are probably platform dependent.
-Rory
Andrej Mitrovic wrote:
I have some D1 code that I'm transfering to D2, and it's using
getchar. I
think I need to flush the buffer or something because the loop tends
to
skip:
import std.c.stdio;
import std.stdio;
void main()
{
char k;
for(int i = 0; i 10; i++)
{
writef(Press key #%d:\t\n, i);
k = cast(char)getchar();
}
}
E.g.:
Press key #0:
a
Press key #1:
Press key #2:
b
Press key #3:
Press key #4:
c
Press key #5:
Press key #6:
I guess I could use scanf() instead.. or maybe something more D-ish
perhaps? :)
Someone on the NGs started creating some user-friendly input
functions,
something like getInput!char(variable), or similar. But I can't find
the
topic, anyone know the link perhaps? It was fairly recent that
someone
posted it.
Re: dmd: Module X conflicts with itself (Was: Re: RDMD on Windows)
Andrej Mitrovic wrote: Doh! I swear I've read somewhere that a module declaration needs to have the same name as the *file name*. I didn't know I had to add the path as well. That makes the modules work now. In fact, I probably just read this one line in the docs: The ModuleDeclaration sets the name of the module and what package it belongs to. *If absent, the module name is taken to be the same name (stripped of path and extension) of the source file name.* But I didn't pay attention to the package stuff. Thanks Nick for the help, I was going slightly mad there for a second. :p Nick Sabalausky Wrote: snip In Java yes. I D you can use the module declaration to move a module. e.g. filename: socket.d; module: alt.socket; to import you'd do import alt.socket; even if the file is in the same directory as the module using the file.
Re: String literals have only one instance?
Rory Mcguire wrote:
Are all string literals that have the same value initialized to the same
address?
void main() {
string same() {
return This;
}
assert(This is same());
assert(This is This);
}
Can this be relied upon?
Interesting thanks guys.
Was just curious about the speed of comparisons for string literals. Because
I believe the string comparisons check if a string is another string
first.
String literals have only one instance?
Are all string literals that have the same value initialized to the same
address?
void main() {
string same() {
return This;
}
assert(This is same());
assert(This is This);
}
Can this be relied upon?
Re: inheriting ctors?
Philippe Sigaud wrote:
On Fri, Aug 6, 2010 at 21:59, Rory Mcguire rjmcgu...@gm_no_ail.com
wrote:
Here is a possible solution to your problem:
-Rory
I believe you can get the type of A. Isn't it typeof(super) or
std.traits.BaseClassesTuple!B[0] ? B in the latter case being typeof(this)
That way, there is no need for the user to provide A, it's automatically
found by the template.
Warning: I did not test this.
And, we know the constructs are of type 'A function(someTypes)' [*], so
the 'A function' part is redundant.
Hence, the user only needs to provide for the args types and that makes
for a cleaner call.
* either as a list :
mixin(InheritConstructors!(int, double, string)); // I want to inherit
the constructors taking one type, build me the __ctors for int, double and
string
* or, in the case of multi-parameters constructors, wrap them in a tuple:
mixin(InheritConstructors!(int, double, Tuple!(int, double)); // I
want
super(int), super(double) and super(int, double)
That means iterating on the type list, and determining if the current type
is a tuple or not
* if its a 'normal' type, create the corresponding contructor
* if it's a Tuple, crack it open and get the types, using the .Types alias
std.typecons.Tuples have. Creating a constructor from this typetuple is no
different from creating it for one type.
To determine if something is a std.typecons.Tuple, you cannot use an is()
expression: they do not allow multiple types:
enum bool isTuple = is(T == Tuple!U, U...); // no. U... is not allowed.
Hmm, enhancement request?
So, you can either rely on it having a .Types 'member':
template isTuple(T)
{
enum bool isTuple = is(T.Types);
}
Pb: that will flag as tuples any type that exposes a .Types alias.
Or use a function accepting a Tuple:
template isTuple(T)
{
enum bool isTuple = is(typeof({
void foo(U...)(Tuple!U t) {}; // this
function accepts only tuples
foo(T.init); // test it
}()));
}
It's ugly as a rat's ass, but it's more solid than the former template.
Philippe
[*] btw, shouldn't that be A delegate(someTypes)???
I'll see what I can do to shorten it but I'm not sure how to iterate over
the Selectors inside the foreach and still be able to skip unselected
constructors. Hmmm I suppose I could use a temporary boolean or something.
I don't use A delegate(someTuypes) because the compiler says that the type
of the constructors is for instance: A function(int x)
Re: inheriting ctors?
I had been trying to use AutoImplement to make something before but it gave me weird errors. I'm going to try using it for implementing this when I get some time. Andrej Mitrovic wrote: Here's an example: [snip]
Re: inheriting ctors?
Philippe Sigaud wrote:
On Fri, Aug 6, 2010 at 11:43, Rory Mcguire rjmcgu...@gm_no_ail.com
wrote:
I've been trying to make a template for this but it seems that dmd still
won't allow me to get the parameters of the constructors. dmd Seems to
think
that I'm trying to use it as a property.
void main() {
foreach (m; __traits(getOverloads, A, __ctor)) {
pragma(msg, m.stringof); // it thinks I'm calling m
}
}
constructors.d(34): Error: constructor constructors.A.this (int x) is not
callable using argument types ()
This is my new once-a-day bug :(
Using a function alias, and being unable to call properties on it, because
DMD thinks I'm calling it. Man, it's no property, just a name!
Anyway, just pragma(msg, m) works, strangely.
I think I found a way to use m, somewhat:
void main() {
foreach (m; __traits(getOverloads, A, __ctor)) {
pragma(msg, m); // it thinks I'm calling m
typeof(m) tmp = m;
writeln( (ParameterTypeTuple!tmp).stringof); // (int), (double),
(string)
writeln( (ParameterTypeTuple!m).stringof); // (int), (int), (int)
writeln( typeof(m).stringof); // A function(int x), A
function(double x), A function(string s)
}
}
using ParameterTypeTuple!m directly does not differentiate the m's. But
using a temporary pointer, it seems to work.
Oh and I even get the arguments names !
Philippe
Thanks!! works now. Now we just need to be able to select which constructors
we actually want.
string inheritconstructors_helper(alias T)() {
string s;
foreach (m; __traits(getOverloads, T, __ctor)) {
string args, args1;
foreach (i, cons; ParameterTypeTuple!(typeof(m))) {
pragma(msg, cons.stringof);
args ~= ,~cons.stringof~ v~to!string(i);
args1 ~= ,v~to!string(i);
}
args = args.length 1 ? args : args[1..$];
args1 = args1.length 1 ? args1 : args1[1..$];
s ~= this(~args~) { super(~args1~); }\n;
}
return s;
}
class A {
int i;
//private this() {}
this(int x) {
i = x;
}
this(float x) {
i = cast(int)x; // ignore bad code
}
this(string s, int mul) { // test multiple args
i = to!int(s) * mul;
}
}
class B : A {
mixin(inheritconstructors_helper!A());
// InheritConstructors!A;
}
void main() {
A a = new B(4);
a = new B(42, 2);
}
Re: inheriting ctors?
Rory Mcguire wrote:
Philippe Sigaud wrote:
On Fri, Aug 6, 2010 at 11:43, Rory Mcguire rjmcgu...@gm_no_ail.com
wrote:
I've been trying to make a template for this but it seems that dmd still
won't allow me to get the parameters of the constructors. dmd Seems to
think
that I'm trying to use it as a property.
void main() {
foreach (m; __traits(getOverloads, A, __ctor)) {
pragma(msg, m.stringof); // it thinks I'm calling m
}
}
constructors.d(34): Error: constructor constructors.A.this (int x) is
not callable using argument types ()
This is my new once-a-day bug :(
Using a function alias, and being unable to call properties on it,
because DMD thinks I'm calling it. Man, it's no property, just a name!
Anyway, just pragma(msg, m) works, strangely.
I think I found a way to use m, somewhat:
void main() {
foreach (m; __traits(getOverloads, A, __ctor)) {
pragma(msg, m); // it thinks I'm calling m
typeof(m) tmp = m;
writeln( (ParameterTypeTuple!tmp).stringof); // (int), (double),
(string)
writeln( (ParameterTypeTuple!m).stringof); // (int), (int), (int)
writeln( typeof(m).stringof); // A function(int x), A
function(double x), A function(string s)
}
}
using ParameterTypeTuple!m directly does not differentiate the m's. But
using a temporary pointer, it seems to work.
Oh and I even get the arguments names !
Philippe
Thanks!! works now. Now we just need to be able to select which
constructors we actually want.
string inheritconstructors_helper(alias T)() {
string s;
foreach (m; __traits(getOverloads, T, __ctor)) {
string args, args1;
foreach (i, cons; ParameterTypeTuple!(typeof(m))) {
pragma(msg, cons.stringof);
args ~= ,~cons.stringof~ v~to!string(i);
args1 ~= ,v~to!string(i);
}
args = args.length 1 ? args : args[1..$];
args1 = args1.length 1 ? args1 : args1[1..$];
s ~= this(~args~) { super(~args1~); }\n;
}
return s;
}
class A {
int i;
//private this() {}
this(int x) {
i = x;
}
this(float x) {
i = cast(int)x; // ignore bad code
}
this(string s, int mul) { // test multiple args
i = to!int(s) * mul;
}
}
class B : A {
mixin(inheritconstructors_helper!A());
// InheritConstructors!A;
}
void main() {
A a = new B(4);
a = new B(42, 2);
}
Got selection working:
string inheritconstructors_helper(alias T,Selectors...)() {
string s;
foreach (m; __traits(getOverloads, T, __ctor)) {
string args, args1;
pragma(msg, typeof(m));
/*foreach (sel; Selectors) {
pragma(msg, sel, is (sel == typeof(m)));
continue top;
}*/
if (staticIndexOf!(typeof(m), Selectors)==-1) {
continue;
}
foreach (i, cons; ParameterTypeTuple!(typeof(m))) {
pragma(msg, cons.stringof);
args ~= ,~cons.stringof~ v~to!string(i);
args1 ~= ,v~to!string(i);
}
args = args.length 1 ? args : args[1..$];
args1 = args1.length 1 ? args1 : args1[1..$];
s ~= this(~args~) { super(~args1~); }\n;
}
return s;
}
Usage:
class B : A {
mixin(inheritconstructors_helper!(A,TypeTuple!(A function(string,int)
,A function(int)))());
}
Re: hijacking a class's members
Mafi wrote:
Am 04.08.2010 12:11, schrieb Rory Mcguire:
Hi,
The code below is my beginning to attempt a class which implements any
class and throws an exception if one tries to access any member of that
class.
Problem is that if I use:
auto a1 = noinit!(A)();
it works and accesses the int x() {...} member of the generated class,
but if I use:
A a1 = noinit!(A)();
it accesses A.x instead of the generated classes x.
So am I wrong in making a sub class have a member function which hides a
parent class's member variable or is the compiler wrong and it should
generate a call to generated sub class?
Thanks!!!
-Rory
Hi,
if x is a field (ie a member variable) it's statically bound. In your
example it is a field so it gets A.x of your subclass which is still
there becuase of the methoda of A which could use A.x.
Fields have to be statically bound because there's no covariance
guarateed with them. Use getters and setters instead.
BTW are @propertys statically or dynamically bound. They're kind of
both: fields and methods.
Mafi
Thats what feels weird to me. a.x can result in different things happening
even though x exists in both A and the generated class. However the
generated class has two fields called x one you can't access anymore and
the @property one.
When I create an instance of the generated class I would expect it to always
to the same thing if I use one of its methods/properties/etc...
Kind of like you would expect the following to print out hello 2:
class A {
string toString() { return hello; }
}
class B : A {
string toString() { return super.toString() ~ 2; }
}
void main() {
A a = new B();
writeln(a.toString()); // uses B.toString()
}
What I've got is:
class A {
int x;
}
class B : A {
int x() { throw new Exception(); }
}
void main() {
A a = new B();
writeln(a.x); // this accesses A.x not B.x
}
just seems like properties are not quite right or something.
-Rory
Re: hijacking a class's members
Mafi wrote:
Thats what feels weird to me. a.x can result in different things
happening even though x exists in both A and the generated class. However
the generated class has two fields called x one you can't access
anymore and the @property one.
When I create an instance of the generated class I would expect it to
always to the same thing if I use one of its methods/properties/etc...
Kind of like you would expect the following to print out hello 2:
class A {
string toString() { return hello; }
}
class B : A {
string toString() { return super.toString() ~ 2; }
}
void main() {
A a = new B();
writeln(a.toString()); // uses B.toString()
}
What I've got is:
class A {
int x;
}
class B : A {
int x() { throw new Exception(); }
}
void main() {
A a = new B();
writeln(a.x); // this accesses A.x not B.x
}
just seems like properties are not quite right or something.
-Rory
If you want that to work, both x have to be virtual (ie dynamically
bound). In D all non-final non-ststic clsss-methods are virtual(1).
Consider the following:
///
class A {
int x = 0;
int getX() { //-- it's virtual
return x;
}
}
class B : A{
int x = 5;
override int getX() { //-- it's virtual too
return x;
}
}
void thinAboutA(A a) {
/* Now a call to a non virtual method
* which results in vtbl lookup. a's vtbl
* contains B.getX().
writeln(a.getX());
/* Non virtual field.
* Has to be statically bound
* to a lookup in A.x
*/
writeln(a.x);
}
void main() {
thinkAboutA(new B);
}
Fields have to be statically bound bcause the compiler doesn't enforce
covariance with fields. So you can:
///
class C : A {
string x = ;
}
void main() {
thinkAboutA(new C); //Should evrything crash now? I won't.
}
//
1) I'm not sure about @propertys.
cool thanks
good example
Re: various questions
Jason Spencer wrote:
== Quote from Rory Mcguire (rjmcgu...@gm_no_ail.com)'s article
Jason Spencer wrote:
== Quote from Rory Mcguire (rjmcgu...@gm_no_ail.com)'s article
Jason Spencer wrote:
I nievely went and replaced foreach (t;
Iota!(str_types.length))
with foreach (t; str_types.length), since the length of that
array is known at compile-time.
Can't use 0 .. str_types.length in the foreach
because compiler is expecting Integer constants so it can make
the template foo into actual code.
This is the part I'm still not getting. Why shouldn't
foreach (t; 0..3)
work? Those are integer constants.
Actually, I think I'm getting it. str_types.length is actually (or
close to) an integer literal, but t is not. t over a range is an int
variable. So at best, the compiler will infer the type of t and try
to get TypeTuple![int] from the mixin, which doesn't help. But it
works in Iota because it only needs a value, and the length property
is not a variable, but a compile-time constant.
I'm not sure what magic gets worked when t is bound to a TypeTuple
that has int literals, but I'm guessing t in that case is not an int
variable, but a compile-time type variable, and it iterates over int
literals. Those work with templ. What I really want to know is does
that foreach run at compile-time or run-time? I suspect compile-time
because it iterates over type variables. But documentation is shakey
:)
I convert str_types.length to its actual value below:
foreach (t; 3) {
...
}
You can't do that (dmd : t.d(6): Error: int is not an aggregate
type)
Yeah, I mis-typed orginally. It was foreach (t;
0..str_types.length) as a range.
The foreach using Iota is unrolled at compile time, bearofile mentioned this
somewhere as well.
Re: various questions
Jason Spencer wrote:
Ok, I've gone over this, adapted it, and mostly understand it. I just
have one question left:
== Quote from bearophile (bearophileh...@lycos.com)'s article
template Iota(int stop) {
...
alias TypeTuple!(Iota!(stop-1), stop-1) Iota;
}
...
foreach (t; Iota!(str_types.length))
What happens at compile-time with this foreach loop?
I nievely went and replaced foreach (t; Iota!(str_types.length))
with foreach (t; str_types.length), since the length of that array
is known at compile-time. That of course bombed, but I don't quite
get why. Is the compiler actually evaluating the foreach loop at
compile time? How could it, when the body makes run-time checks? If
it's not, why doesn't my change work?
Jason
your replacement tries to loop over an uint called str_types.length. Never
gonna happen.
Iota!(str_types.length) seems to generate str_types.length(a number of)
integer indexes. Can't use 0 .. str_types.length in the foreach because
compiler is expecting Integer constants so it can make the template foo
into actual code.
Re: various questions
Jason Spencer wrote:
== Quote from Rory Mcguire (rjmcgu...@gm_no_ail.com)'s article
Jason Spencer wrote:
I nievely went and replaced foreach (t; Iota!(str_types.length))
with foreach (t; str_types.length), since the length of that
array is known at compile-time.
your replacement tries to loop over an uint called str_types.length.
Never gonna happen.
Iota!(str_types.length) seems to generate str_types.length(a number
of)integer indexes. Can't use 0 .. str_types.length in the foreach
because compiler is expecting Integer constants so it can make the
template foo into actual code.
Not quite sure I follow. I think you're saying the range in foreach
has to be actual literals, and not just an expression that can be
evaluated at compile time to generate the same range...close?
If that's the case, then why does it work to instantiate Iota! with
str_types.length? It can obviously get the value behind it at compile
time. I'm still missing something.
Jason
I convert str_types.length to its actual value below:
foreach (t; 3) {
...
}
You can't do that (dmd : t.d(6): Error: int is not an aggregate type)
Re: Stack traces on exceptions in D2?
Nick Sabalausky wrote: Is there a way to get stack traces on exceptions in D2? What OS. I'm on linux and I get stack traces.
Re: Stack traces on exceptions in D2?
Nick Sabalausky wrote: Nick Sabalausky a...@a.a wrote in message news:i2rbht$22v...@digitalmars.com... Rory Mcguire rjmcgu...@gm_no_ail.com wrote in message news:i2rafu$20l...@digitalmars.com... Nick Sabalausky wrote: Is there a way to get stack traces on exceptions in D2? What OS. I'm on linux and I get stack traces. Windows. Must be a debug-only thing though (not sure why I thought otherwise). I've been unable to actually build in debug mode though, because 2.046 gives me phobos errors if I use debug mode, and 2.076 can't do array(filter()) which is a breaker for me. I guess I could try 2.045. Hmm, weird, I'm not getting the Phobos error with debug-mode on 2.076 now. But still not getting stack traces though, even with both -debug and -g interesting, I get them on 2.046 with and without -debug but not with - release.
Re: SIGSEGV in rt_finalize
Steven Schveighoffer wrote:
On Wed, 28 Jul 2010 11:45:59 -0400, Rory Mcguire rjmcgu...@gm_no_ail.com
wrote:
Hi guys,
I have a 265 line program that gets a segmentation fault if I don't
comment
out this while loop(I am not using delete or anything like it):
/+ while (lines.length 0 line.length 3 line[3]=='-') {
line ~= lines[0];
lines = lines[1..$];
}+/
Any Ideas on how to track this one down?
No, please post the whole code, or a reduced example. What compiler
version/platform?
-Steve
I'll try make a reduced example.
Re: struct opCall error messages
Jacob Carlborg wrote:
On 2010-07-26 14:27, Rory Mcguire wrote:
Hi,
I'm not sure this is in bugzilla, I tried finding something mentioning it
but coudn't.
Compiling the below code results in the dmd compiler printing:
struct_bad_error.d(8): Error: 'this' is only defined in non-static member
functions, not inner
struct S {
S opCall() {S s; return s;}
}
void main() {
S s;
//s = S(); // decent error message: struct_bad_error.d(6):
// Error: need 'this' to access member opCall
void inner() {
s = S();
}
}
=
What to do? Also found that having an empty () after the struct name is
not the best error message: struct_bad_error.d(5): Error: struct
struct_bad_error.S() is used as a type
Surely it could tell me I need to put an Identifier in the ()
-Rory
Perhaps you want a static opCall ?
S foo;
foo(); // calls opCall
S(); // calls static opCall
doh! [slaps head]
Thanks
Re: Threading errors.
Philippe Sigaud wrote:
On Mon, Jul 26, 2010 at 19:11, dcoder dco...@devnull.dev wrote:
== Quote from Rory Mcguire (rjmcgu...@gm_no_ail.com)'s article
Dmitry Olshansky wrote:
std.typecons.Tuple fields cannot be indexed like arrays, Andrei made a
mistake. To access field #n, use ._n or .field[n]. There is no difference
between the two.
void writer() {
for( ;; ) {
auto msg = receiveOnly!(Tid, int)(); // msg is a Tuple!(Tid, int),
msg._0
is a Tid, msg._1 is an int.
writeln( Secondary thread: , msg._1);
msg._0.send(thisTid);
}
}
Also, in my case, the return; in writer must be commented out, or DMD
complains it cannot be reached.
Philippe
Interesting, I didn't have to comment out return; using dmd 2.047 on linux
Re: Threading errors.
Philippe Sigaud wrote: On Tue, Jul 27, 2010 at 11:25, Rory Mcguire rjmcgu...@gm_no_ail.com wrote: Also, in my case, the return; in writer must be commented out, or DMD complains it cannot be reached. Interesting, I didn't have to comment out return; using dmd 2.047 on linux I think I have -w (warnings treated as errors?) always checked. That's my Code::Blocks default configuration for DMD. I was on Windows for this test. I never cheked if there was any difference between OSes for this :-) :) thanks Philippe
Re: D and cygwin io.
dcoder wrote:
Hello. Here's a short program that works in a dos window:
import std.stdio;
void main() {
writef( What is your name?);
string name = readln();
writefln( Hello ~ name);
}
The program prints a prompt without a newline and the user enters a name
and a greeting is printed.
The same program does not seem to work when at a cygwin prompt. The
program
seems to pause. It is actually waiting for input. So, if I type in a
name and hit return, the prompt and the greeting appears as expected but
on one line.
I can change writef to writefln and it will work on the cygwin prompt and
on the dos prompt, but now a newline will be added after the prompt
message.
I'm wondering how can I fix this? I am using bash shell on cygwin.
thanks.
try flushing the output after the write: stdout.flush();
struct opCall error messages
Hi,
I'm not sure this is in bugzilla, I tried finding something mentioning it
but coudn't.
Compiling the below code results in the dmd compiler printing:
struct_bad_error.d(8): Error: 'this' is only defined in non-static member
functions, not inner
struct S {
S opCall() {S s; return s;}
}
void main() {
S s;
//s = S(); // decent error message: struct_bad_error.d(6):
// Error: need 'this' to access member opCall
void inner() {
s = S();
}
}
=
What to do? Also found that having an empty () after the struct name is not
the best error message: struct_bad_error.d(5): Error: struct
struct_bad_error.S() is used as a type
Surely it could tell me I need to put an Identifier in the ()
-Rory
std.socket.TcpSocket.flush
Hi, What is one supposed to use to flush a TcpSocket. flush doesn't seem to exist, should I really just use the c function? -Rory
Re: std.socket.TcpSocket.flush
Heywood Floyd wrote: Rory Mcguire Wrote: Hi, What is one supposed to use to flush a TcpSocket. flush doesn't seem to exist, should I really just use the c function? -Rory Was in a similar situation, found this: http://stackoverflow.com/questions/855544/is-there-a-way-to-flush-a- posix-socket I thought a socket needed to be flushed because curl and ab hanged when GETting from my server. Turns out I was just not sending the correct HTTP-headers... /HF Thanks. I've made this before but it was about 3 years ago now, and I can't remember what I did. Perhaps it was just TCP_NODELAY. telnet,smtp,http1.1, etc... all rely on the ability to send data without the while the client waits for a specific line. I'm sending a line when the client connects, which the client has to read in order to acknowledge, with a write but it never gets the data from the server. Suppose I'll have to find my backups... somewhere :(.
Detecting a property setter?
Hi,
Does anyone know how to detect if there is a setter for a property? The
code below prints the same thing for both
the setter and the getter of front:
==
import std.traits;
class Foo {
uint num;
@property ref uint front() {
return num;
}
@property void front(uint i) {
num = i;
}
ref uint front2() {
return num;
}
}
template isProperty(alias func) if (isCallable!(func)) {
enum isProperty = (functionAttributes!(func)
FunctionAttribute.PROPERTY)==0 ? false : true;
}
template hasSetter(alias func) if (isCallable!(func)) {
enum hasSetter = (isProperty!(func) ParameterTypeTuple!(func).length
0 ReturnType!(func).stringof != void) ? true : false;
}
void main() {
Foo foo;
pragma(msg, hasSetter!(foo.front));
static if (isProperty!(foo.front)) {
pragma(msg, property);
} else {
pragma(msg, not a property);
}
alias MemberFunctionsTuple!(Foo,front) fronts;
foreach (s; fronts) {
pragma(msg, ReturnType!(s)); // this line just prints uint
for both
front properties!
}
}
Is this a compiler bug? Or am I wrong again?
Thanks
Rory
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Re: Detecting a property setter?
On Mon, 19 Jul 2010 22:06:14 +0200, Simen kjaeraas
simen.kja...@gmail.com wrote:
Rory McGuire rmcgu...@neonova.co.za wrote:
Does anyone know how to detect if there is a setter for a property? The
code below prints the same thing for both
the setter and the getter of front:
==
import std.traits;
class Foo {
uint num;
@property ref uint front() {
return num;
}
@property void front(uint i) {
num = i;
}
ref uint front2() {
return num;
}
}
template isProperty(alias func) if (isCallable!(func)) {
enum isProperty = (functionAttributes!(func)
FunctionAttribute.PROPERTY)==0 ? false : true;
}
template hasSetter(alias func) if (isCallable!(func)) {
enum hasSetter = (isProperty!(func)
ParameterTypeTuple!(func).length
0 ReturnType!(func).stringof != void) ? true : false;
}
For what it's worth, I would simply check if the property allows
assignment. i.e.:
template hasSetter(alias func) if (isCallable!(func)) {
enum hasSetter = isProperty!(func)
is( typeof( (){ func = ReturnType!(func).init; } ) );
}
Hehe good solution, never even crossed my mind.
And it doesn't match ref return types such as the following signature.
ref uint front() { return num; }
My test code below:
===
import std.traits;
class Foo {
uint num;
@property ref uint front() {
return num;
}
/+@property void front(uint i) {
num = i;
}+/
ref uint front2() {return num;}
}
template isProperty(alias func) if (isCallable!(func)) {
enum isProperty = (functionAttributes!(func)
FunctionAttribute.PROPERTY)==0 ? false : true;
}
template hasSetter(alias func) if (isCallable!(func)) {
enum hasSetter = isProperty!(func)
is( typeof( (){ func = ReturnType!(func).init; } ) );
}
void main() {
Foo foo;
pragma(msg, hasSetter!(foo.front)); // is the return type null (setter)
static if (isProperty!(foo.front)) {
pragma(msg, property);
} else {
pragma(msg, not a property);
}
alias MemberFunctionsTuple!(Foo,front) fronts;
foreach (s; fronts) {
pragma(msg, hasSetter!(s));
}
}
Could be used in a GUI library for checking which properties of a class
are editable and which are only for display.
And tell you about it at compile time.
Thanks!
Re: Detecting a property setter?
On Mon, 19 Jul 2010 23:25:01 +0200, Jonathan M Davis
jmdavisp...@gmail.com wrote:
On Monday, July 19, 2010 13:42:51 Philippe Sigaud wrote:
On Mon, Jul 19, 2010 at 22:06, Simen kjaeraas
simen.kja...@gmail.comwrote:
template hasSetter(alias func) if (isCallable!(func)) {
enum hasSetter = isProperty!(func)
is( typeof( (){ func = ReturnType!(func).init; } ) );
}
In that case, for the second func, the one you call ReturnType on, how
does
the compiler knows it must take the ref uint one (the getter) and not
the
void func() one?
Philippe
I don't think that you're supposed to be able to have a getter property
returning a ref at the same time that you have a setter property with
the same
name. It certainly sounds like it should be a bug in any case.
- Jonathan M Davis
I suppose it would be seen as a bug because it possibly circumvents the
getter/setter
philosophy (If you return the internal value anyway).
Re: Detecting a property setter?
On Mon, 19 Jul 2010 22:42:51 +0200, Philippe Sigaud philippe.sig...@gmail.com wrote:On Mon, Jul 19, 2010 at 22:06, Simen kjaeraas simen.kja...@gmail.com wrote:
template hasSetter(alias func) if (isCallable!(func)) {
enum hasSetter = isProperty!(func)
is( typeof( (){ func = ReturnType!(func).init; } ) );
}In that case, for the second func, the one you call ReturnType on, how does the compiler knows it must take the ref uint one (the getter) and not the void func() one?Philippe
Simen is using the fact that the compiler already has to figure out if there is an overload that matches the requirements. So it ends uptaking the only one that works. Since it seems to ignore the ref return type property, the property that takes an uint argument must have ahigher precedence (gets checked if it works first).I wonder if its because Walter probably implemented function overloading before properties and ref return types. Hopefully its a languagefeature and not just a implementation side effect.-Rory
Anyone know why this CTFE isn't working?
import std.stdio;struct State { string s; string getString() { return s; } static State opCall(string s) { State ret; ret.s = s; return ret; }}void main() { auto s = State("adf"); pragma(msg, s.getString());}dmd Output: (line 14 is the pragma statement)struct.d(14): Error: variable s cannot be read at compile timestruct.d(14): Error: cannot evaluate s.getString() at compile times.getString()
Rory McGuire
R
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Re: Anyone know why this CTFE isn't working?
Sorry about the html
On Fri, 16 Jul 2010 11:46:48 +0200, Rory McGuire rmcgu...@neonova.co.za
wrote:
import std.stdio;
struct State {
string s; string getString() { return s; }
static State opCall(string s) {
State ret;
ret.s = s;
return ret;
}
}
void main() {
auto s = State(adf);
pragma(msg, s.getString());
}
dmd Output: (line 14 is the pragma statement)
struct.d(14): Error: variable s cannot be read at compile time
struct.d(14): Error: cannot evaluate s.getString() at compile time
s.getString()
Re: Anyone know why this CTFE isn't working?
On Fri, 16 Jul 2010 11:58:57 +0200, Lars T. Kyllingstad
pub...@kyllingen.nospamnet wrote:
On Fri, 16 Jul 2010 11:46:48 +0200, Rory McGuire wrote:
import std.stdio;
struct State {
string s; string getString() { return s; } static State opCall(string
s) {
State ret;
ret.s = s;
return ret;
}
}
void main() {
auto s = State(adf);
pragma(msg, s.getString());
}
dmd Output: (line 14 is the pragma statement)
struct.d(14): Error: variable s cannot be read at compile time
struct.d(14): Error: cannot evaluate s.getString() at compile time
s.getString()
It's not working because s isn't a compile-time quantity. Try:
enum s = State(adf);
-Lars
Awesome thanks, worked.
So is the difference that auto s is a Struct which can change whereas
enum s is a constant?
If it is a constant its just s that is constant right?
Thanks Lars
-Rory
Re: Anyone know why this CTFE isn't working?
On Fri, 16 Jul 2010 12:05:02 +0200, Jonathan M Davis
jmdavisp...@gmail.com wrote:
On Friday 16 July 2010 02:46:48 Rory McGuire wrote:
import std.stdio;
struct State {
string s; string getString() { return s; }
static State opCall(string s) {
State ret;
ret.s = s;
return ret;
}
}
void main() {
auto s = State(adf);
pragma(msg, s.getString());
}
Make s an enum and it'll work. As it is, it's a local variable created at
runtime rather than a constant at compile-time. So, use
enum s = State(adf);
- Jonathan M Davis
Thanks
worked
Re: Best practice and module declarations
On Thu, 15 Jul 2010 00:22:34 +0200, Jonathan M Davis jmdavisp...@gmail.com wrote: I was wondering what the general consesus was (if there is one) on whether it's valuable to always put module declarations in each module. Obviously, if you need the module to have a name other than the file name, then you need to have the module declaration. However, is it necessarily desirable to have it when the module name matches the file name? Or would there even be a reason for it to be desirable _not_ to have the module declaration? I can't think of any particularly strong reasons to have it or not to have it. My first reaction is to just always use it, but thinking about it, I'm not sure that there's really much point if the file name and the module name already match. Does anyone have reasons why it would matter other than personal preference? - Jonathan M Davis From what I remember in TDPL: Can be used to rename a module if you have it in a different directory structure than how you use it. E.g. implementation and headers in separate folders. Can be used to rename module when a filename is not a valid D symbol. -Rory
Re: Best practice and module declarations
On Thu, 15 Jul 2010 23:08:07 +0200, torhu n...@spam.invalid wrote: On 15.07.2010 21:59, Rory McGuire wrote: From what I remember in TDPL: Can be used to rename a module if you have it in a different directory structure than how you use it. E.g. implementation and headers in separate folders. If you use *.di files (headers), you would normally just keep the directory structure, but put the whole thing in a different root directory. Just having *.d and *.di files in the same directory works too, as the compiler prefers the *.di files. Andrei's use case was if you had multiple teams of programmers with some allowed to work on interfaces and others only allowed to work on the implementations. Can be used to rename module when a filename is not a valid D symbol. That would fool the D-specific build tools, and DMD itself too. In most cases it's easier to just rename the file too. It can be made to work using a *.di file if you really have to. Andrei's example had hyphens in the file name, sometimes policy comes first? yes no. Not that I can think of a reason for the policy off hand perhaps GTK naming convention.
Re: Recommended way to do RAII cleanly
On Mon, 12 Jul 2010 08:25:32 +0200, Jonathan M Davis
jmdavisp...@gmail.com wrote:
Okay. There are cases where you want a constructor to do something when
the
class/struct is created, and you want the destructor to do something
when the
class/struct goes out of scope. A classic example would be an autolock
for a
mutex. Another would be the hourglass in MFC - it's displayed when the
object is
created and disappears when the object is destroyed (so all you have to
do is
declare the object it at the beggining of the function and it
automatically is
displayed and then disappears). This is classic RAII.
Obviously, because classes are reference types with infinite lifetime
while
structs are value types with their lifetime restricted to their scope,
structs
would be the better choice for RAII. I have noticed a bit of a snag
however:
structs can't have default constructors.
After reading TDPL, I completely understand that structs can't have
default
constructors due to how the init property works. However, the classic
case where
you want to simply declare an object and have it do what it does through
RAII
then falls apart. Ideally, you'd have something like this
struct S
{
this()
{
/* do something */
}
~this()
{
/* undo what you did before or do whatever clean up is required
for it */
}
}
void main()
{
auto s = S();
/* whatever the rest of main() does */
}
Thanks to the lack of default constructor, you can't do that. Therefore,
I see 2
options:
1. Create a nonsensical constructor that takes an argument of _some_
kind which
is totally ignored.
2. Create a factory function to create the struct, and it does whatever
would
have been in the default constructor.
Out of those two options, the second seems the best, but it seems to me
that
there have got to be more options than that. So, the question is what
would be
the best option (be it one of those or another that I haven't though of)
to do
RAII in the general case? What would be best practice for D when
dealing with
structs intended for RAII without any arguments to their constructor
when you
can't have a default constructor?
- Jonathan M Davis
Do you know about the scope storage class, or about scope classes?
{
scope tmp = new A();
// use tmp;
tmp destructor is called.
}
scope classes are similar:
http://www.digitalmars.com/d/2.0/class.html
Re: std.pattern.. templated publisher subscriber pattern, adding events to collections
On Wed, 07 Jul 2010 00:47:32 +0200, BLS windev...@hotmail.de wrote:
Okay a bit better snippet than before. snippet should be almost
functional..
/*
Hi,
Andrei brings in the idea of std.pattern. Seems that this module is
stalled; Unfortunately !
However I would like to enhance collection classes (likewise
dcollections) with a Publisher - Subscriber pattern (signal - slot, or
observer pattern) , if you prefer)
Hope the idea of enhancing collections with events become clear with the
following snippet.
!!! I am able to spend just a few hours a month with D programming.. in
other words, please don't kill me :)
Untested Draft code which requires a lot of help and ,more important,
feedback from you.
*/
struct publisherMsg(T) {
T data;
Action a;
}
mixin template Publisher(T) {
private :
enum Action = {INSERT, UPDATE, DELETE, READONLY};
//alias typeof(this) PT;
struct receiver {
Object o;
callback cb;
}
receiver[] subscriber;
publisherMsg!(T) msg;
alias void delegate(const ref msg) callback;
void addSubscriber(object o, callback cb) {
//subscriber ~= o;
}
void publish() {
foreach (object o ; subscriber)
{
// create message and send message
}
}
}
mixin template Subscriber() {
// see UndoList for implementation
}
final class Stack(T, bool observable = false ) {
T[] data;
static if (observable) mixin Observable!T;
void push( T t) {
data ~= t;
publish(t, Action.INSERT);
}
T pop() {
publish(t, Action.DELETE);
//...
}
bool empty() {
}
T top() {
publish(t, Action.READONLY);
//...
}
size_t size() {
}
}
// Undo list will receive every pushed or popped item -data and action)
class UndoList(T) {
private:
T[] data;
/// should be part of the sunscriber mixin templates.
publisherMsg!T stackMessage;
void delegate(const ref stackMessage) dg;
alias Stack!(int) IntegerStack;
IntegerStack intstack = new IntegerStack;
private this() {
dg = this.feedback;
// SUBBSCRIBE Stack(T) push and pop events.
intstack.addSubscriber(this, dg);
}
public void feedback(const ref stackMessage msg ) {
writefln(Action);
}
}
Hi Bjoern,
your mixin template should have private { ... } rather than private: I
believe the current way will make
everything that uses the mixin template private after its used.
Re: Grokking std.container and Ranges
On Tue, 29 Jun 2010 07:16:13 +0200, BCS n...@anon.com wrote:
Hello Mike,
I want to do the following:
foreach(obj; list)
{
if(obj.pleaseKillMe)
somehow_remove_the_object_from_the_list();
}
That isn't legal for normal arrays or AAs. IIRC the docs even say that
you can't change what a foreach is iterating over during the foreach. I
think you will have to convert to a manual for loop to make it work.
That said, I've not worked with range at all.
Perhaps keep the foreach and make a list of to be deleted objects and then
delete them after the foreach.
Re: @property and interfaces
On Tue, 29 Jun 2010 14:42:33 +0200, BLS windev...@hotmail.de wrote: Hi bearophile, sorry for my ignorance, but what is the difference between @disable and simply deleting the line ? where can I read more about @disable ? thanks, bjoern @disable propagates throughout the objects hierarchy (all children). you can use it to disable builtins as well such as opEquals
Re: A module comprehensive template-specialization
On Mon, 28 Jun 2010 11:09:13 +0200, Matthias Walter
xa...@xammy.homelinux.net wrote:
On 06/28/2010 09:49 AM, Justin Spahr-Summers wrote:
On Sun, 27 Jun 2010 18:51:35 +0200, Matthias Walter
xa...@xammy.homelinux.net wrote:
Hi list,
I tried to write a traits class comparable to iterator_traits in C++
STL
or graph_traits in Boost Graph Library in D 2.0, but failed to do so
via
template specialization which is put into different modules. Putting
everything into one module interferes with extensibility. I tried the
following:
== Module a ==
| module a;
|
| template Base (T)
| {
| alias T Base;
| }
== Module b ==
| module b;
|
| import a;
|
| template Base(T: T*)
| {
| alias Base !(T) Base;
| }
== Main module ==
|
| import a, b;
|
| int main(char[][] args)
| {
| alias Base !(int*) foo;
|
| return 0;
| }
The error message is:
bug.d(8): Error: template instance ambiguous template declaration
b.Base(T : T*) and a.Base(T)
Can I handle this in another way (like making the template a
conditional
one)?
best regards
Matthias Walter
I believe this is intended behavior, as it prevents template hijacking
and the like. Using alias to import the two templates into the same
scope might help, though I'm not sure exactly how it should be done.
I tried to do so in some variants but did not succeed unfortunately. If
you have a precise idea, please let me know!
On another note, though, have you looked at __traits() and std.traits?
I looked at them but didn't find them helpful for this precise problem.
The whole reason for doing this is to make it possible to make another
existing class model the concept (i.e. have some aliases / typedefs
done) of my library class without editing any of them. As I mentioned in
my other response, a prominent example for Boost Graph
Library is the LEDA graph class, which can be enabled to be used by BGL
by more or less just specializing the graph_traits template. I'd like to
have this kind of technique available, too.
Any further suggestions?
I haven't looked at the boost stuff you mention but is it possible that
using alias this, solves a similar or the same problem?
TDPL addresses the use of aliasing to bring multiple declarations into the
same scope/module but it only uses actual functions not templates.
Re: auto functions not authorized inside main?
On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud
philippe.sig...@gmail.com wrote:
Is it defined somewhere that auto functions are not authorized inside
main?
void main()
{
auto fun(string s) { return s;} // this does not compile
}
error:
main.d|6|found 's' when expecting ')'|
main.d|6|semicolon expected, not ')'|
main.d|6|found ')' instead of statement|
main.d|7|unrecognized declaration|
||=== Build finished: 4 errors, 0 warnings ===|
So it's not even parsed?
I couldn't find a bugzilla entry for this and I cannot believe no one
ever
tried to put an auto fun inside main!
Is that part of the spec?
Philippe
Hope this isn't a stupid question, but how would you access this function
if it did work?
Would it be fun(asdf)?
Is this just shorthand for:
auto fun = function(string s) {return s;};
-Rory
Re: auto functions not authorized inside main?
On Mon, 28 Jun 2010 16:07:43 +0200, Philippe Sigaud philippe.sig...@gmail.com wrote:On Mon, Jun 28, 2010 at 15:40, Rory McGuire rmcgu...@neonova.co.za wrote:
void main()
{
auto fun(string s) { return s;} // this does not compile
}
Hope this isn't a stupid question, but how would you access this function if it did work?
Would it be fun("asdf")?Yes, that's what I had in mind. Basically, just using it as any other auto inner function. void main(){auto fun(string s) { return s;}auto s = fun("abc");
auto t = fun("def");}
Is this just shorthand for:
auto fun = function(string s) {return s;};That'd be about the same, yes. Fact is, I don't really _need_ this, I was just astonished to be bitten by this.Why can I do
void main(){ string foo(string s) { return s;}}and notvoid main(){ auto foo(string s) { return s;}} ?***OK, I tested it some more, and it seems you cannot define auto function inside any other function. So auto function cannot be inner functions. I'm quite astonished I never did that when using D, but OK.
I filed a bug report, at least to update the docs. It's bug #4401.Philippe
Right! I get what you're saying, didn't realise because it was formatted more how I would format a anon delegate.You're saying "surely the compiler can infer the return type for a inner function just as much as it can infer the return type of a normal function..Must be a compiler bug.-Rory
Re: auto functions not authorized inside main?
On Mon, 28 Jun 2010 16:01:46 +0200, BCS n...@anon.com wrote:
Hello Rory,
On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud
philippe.sig...@gmail.com wrote:
void main()
{
auto fun(string s) { return s;} // this does not compile
}
Hope this isn't a stupid question, but how would you access this
function
if it did work?
Would it be fun(asdf)?
Is this just shorthand for:
auto fun = function(string s) {return s;};
I would look almost the same to the user but should in fact be a normal
local function.
Ye I got it now.
My brain was interpreting it as a delegate that wasn't being assigned to
anything for some reason.
Now I get that it is just return type inferance doesn't work for inner
functions.
-Rory
Re: @porperty problem..
On Mon, 28 Jun 2010 22:37:06 +0200, BLS windev...@hotmail.de wrote:
Hi I have a forward reference pb in conjunction with @property.
Err msg is :
forward refrence to inferred return type of function call s1.servername.
any ideas ? beside, where are the @property docs ?
thanks, bjoern
final class LoadBalancer {
private static LoadBalancer lb;
private Server[] servers;
static this() {
synchronized lb = new LoadBalancer;
}
private this() {
Server s1 = new Server();
s1.servername = Server 1; // ERROR
servers ~= s1;
}
public static LoadBalancer getLoadBalancer() {
return lb;
}
@property nextServer() {
return servers[0];
}
class Server {
private string _name, _id;
@property servername(string name) {
_name = name;
}
@property servername() {
return _name;
}
}
}
Only place I've seen @property docs is in TDPL
Re: Cannot initialize associative array.
On Wed, 23 Jun 2010 00:30:40 +0200, Ali Çehreli acehr...@yahoo.com wrote:
dcoder wrote:
So, I moved the initialization to inside the main function, and now
it works.
Great. I think we need to put this question in the FAQ.
For future reference, if it really needs to be global:
uint[string] mywords;
static this()
{
mywords = [ Hello : 1, World : 1, Cat : 1, Dog : 1 ];
}
Ali
from what I have read in TDPL so far (about half way now), there is no
mention of this limitation.
It just says that [key:value] is how you would statically initialize a AA.
Does this mean that it is just a D implementation issue. To me its seems
like this should be a defined part
of the language. Also the compiler should really rewrite it to your above
code anyway, surely?
-Rory
Re: Tempated class instantiation
Mike L. sgtmuff...@myrealbox.com wrote:
Simen kjaeraas Wrote:
On Wed, 16 Dec 2009 07:25:39 +0100, Mike L. sgtmuff...@myrealbox.com
wrote:
I'm making a class template that only works with strings, so I thought
it'd be good to instantiate each template with char, wchar, and dchar
right in the template's module so that when it's compiled it'll be part
of the .obj file and won't have to compile it for every other project
that uses it. However, I get an error reproducible with this:
module test;
class A(T)
{
version(broken)
{
class B
{
T blah() { return t; }
}
}
T t;
}
mixin A!(int);
int main()
{
A!(int) a = new A!(int)();
return 0;
}
If what I want to do makes sense, how should I be doing it?
It makes sense. Seems to be another compiler bug, but I have
no good overview of which (might even be a new one).
This compiles and runs:
class A(T)
{
version(broken)
{
class B
{
// Explicitly state which t we're talking about.
T blah() { return this.outer.t; }
}
}
T t;
}
mixin A!(int);
int main()
{
A!(int) a = new A!(int)();
return 0;
}
--
Simen
Thanks for the reply, that seems to be working for my project too, but the
code gets really ugly really fast. Should I submit a bug report?
--Mike L.
As grauzone said, you have to use an alias, or you could use a template. but
the
code above just does the same old templated class instantiation, you can leave
out the mixin A!(int); line completely.
As far as I understand it a template is always evaluated at least once for each
type T. So perhaps if you used it in the module that declares it the compiler
would detect that it doesn't need to compile it again but I'm not convinced of
that because the instance is in a different module.
-Rory
Re: why can't structs implement interfaces?
Saaa em...@needmail.com wrote:
struct S : Pos {}
Why is this not possible?
Why do you want to use a struct for that, rather than a class?
Re: reading files from a directory
miriac 1234...@gmail.com wrote: Jesse Phillips Wrote: miriac Wrote: I'm trying to get my program to read all the files in a directory. dmd gives an errer that theis imports dont exist: tango.io.FileSystem, tango.io.FileRoots, Can someone please help me and tell me what i use to do so? thanxs M As jcc7 mentioned it sounds like you're using a Tango example without installing Tango first. For more details about starting with D: http://www.prowiki.org/wiki4d/wiki.cgi?D__Tutorial/StartingWithD I really do want to stick to tongo, i instaled it with the instructions in the tongo book but i can try downlding it again and see if it works thanks My reply before checking the docs: if its not working after installation then the import paths are incorrect. you could start by checking that. and also note that tango trunk and the latest tango release are somewhat different. also it looks like you should be using trunk because the next release is due out shortly. My reply after checking the api docs: I don't see tango.io.FileRoots anywhere, check the version of tango you are trying to use.
Re: How to set non-static variable in static method within class
Sam Hu samhu.sa...@nospam.com wrote: Ary Borenszweig Wrote: You can't access non-static data from a static method. Non-static data is related to an instance of a class, and a static method is not bound to any instance. Why do you want to do that? Say I want to implement an utility dialog, InputDialog in DFL which is a subclass of Form,using its static method I can call InputDialog.getString to retrieve a string from the textbox of this dialog other than create an instance of InputDialog,at the mean time I want to customize the caption text and the prompt message of the InputDialog in the static method InputDialog.getString.But I can't modify Form.text, (form.)TextBox.text in the static method.Currently I have to use its non-static version of getString method and create an instance of the dialog each time when I call getString. since non-static data is only created with an instance you would have to use some sort of Singleton or something, I suppose.
