Re: is there any reason UFCS can't be used with 'new'?
I can't understand how to use UFCS with instance of class:
void main()
{
string name = Suliman;
userName username = new userName(name);
/// How to use UFCS here?
userName.name.sayHello();
///
}
class userName
{
string name;
this(string name)
{
this.name = name;
}
void sayHello(string name)
{
writeln(name);
}
}
Re: is there any reason UFCS can't be used with 'new'?
On Mon, 10 Nov 2014 19:07:38 + Suliman via Digitalmars-d-learn digitalmars-d-learn@puremagic.com wrote: /// How to use UFCS here? userName.name.sayHello(); /// you can't. a little explanation: UFCS substitutes only the first argument. and for class methods first argument is hidden 'this'. so you can't do it in this way, you have to write `userName.sayHello(name);` here. on the very low level calling class methods looks like this: // what you see: myobj.method(arg); // what compiler does: // method(myobj, arg); so in your example compiler sees this: sayHello(userName.name); which is obviously not what you want, 'cause you need this: sayHello(userName, name); or, taking it the easier way: UFCS is for *functions*, not for *methods*. that's why it uniform *function* call syntax. it's not expected to work with methods, as the name suggests. maybe it will be easier to remember this way, rather than diving into compiler code transformations. ;-) signature.asc Description: PGP signature
Re: is there any reason UFCS can't be used with 'new'?
On Mon, 10 Nov 2014 19:07:38 +, Suliman wrote:
I can't understand how to use UFCS with instance of class:
void main()
{
string name = Suliman;
userName username = new userName(name);
/// How to use UFCS here?
userName.name.sayHello();
///
}
class userName {
string name;
this(string name)
{
this.name = name;
}
void sayHello(string name)
{
writeln(name);
}
}
This has nothing to do with new--you're trying to use a virtual function
scoped
to class userName with a string. Rewrite it to a static module-scoped
function:
class userName {
string name;
this(string name)
{
this.name = name;
}
}
void sayHello(string name)
{
writeln(name);
}
void main()
{
string name = Suliman;
userName username = new userName(name);
userName.name.sayHello();
}
Re: is there any reason UFCS can't be used with 'new'?
On 11/10/2014 11:07 AM, Suliman wrote:
I can't understand how to use UFCS with instance of class:
void main()
{
string name = Suliman;
userName username = new userName(name);
/// How to use UFCS here?
userName.name.sayHello();
///
}
class userName
{
string name;
this(string name)
{
this.name = name;
}
void sayHello(string name)
{
writeln(name);
}
}
UFCS is about calling a free-standing function like a member function.
The following example makes more sense to me:
void main()
{
string name = Suliman;
userName username = new userName(name);
username.sayHello();// UFCS
}
// Does not have a sayHello() member function
class userName
{
string name;
this(string name)
{
this.name = name;
}
}
void sayHello(userName u)
{
import std.stdio;
writeln(u.name);
}
Ali
Re: is there any reason UFCS can't be used with 'new'?
Thanks! Ali Çehreli, could you add this mention and possible the example to your book?
Re: is there any reason UFCS can't be used with 'new'?
On 11/10/2014 12:04 PM, Suliman wrote: Thanks! Ali Çehreli, could you add this mention and possible the example to your book? Of course. Perhaps I should rephrase some of the descriptions here? http://ddili.org/ders/d.en/ufcs.html Please email me at acehr...@yahoo.com if you have specific suggestions. Thank you, Ali
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 20:28:11 UTC, Jay wrote:
fwiw here's what i wrote:
template New(T) if (is(T == class)) {
T New(Args...) (Args args) {
return new T(args);
}
}
My try
template New(T) if (is(T == class))
{
T New(Args...) (Args args) {
return new T(args);
}
}
unittest
{
class C { int x, y; }
auto x = New!C;
}
fails as
typecons_ex.d(60,16): Error: outer function context of
typecons_ex.__unittestL64_4 is needed to 'new' nested class
typecons_ex.__unittestL64_4.C
typecons_ex.d(67,14): Error: template instance
typecons_ex.New!(C).New!() error instantiating
Re: is there any reason UFCS can't be used with 'new'?
On 09/30/2014 10:35 AM, Nordlöw wrote:
On Sunday, 28 September 2014 at 20:28:11 UTC, Jay wrote:
fwiw here's what i wrote:
template New(T) if (is(T == class)) {
T New(Args...) (Args args) {
return new T(args);
}
}
My try
template New(T) if (is(T == class))
{
T New(Args...) (Args args) {
return new T(args);
}
}
unittest
{
class C { int x, y; }
auto x = New!C;
}
fails as
typecons_ex.d(60,16): Error: outer function context of
typecons_ex.__unittestL64_4 is needed to 'new' nested class
typecons_ex.__unittestL64_4.C
typecons_ex.d(67,14): Error: template instance
typecons_ex.New!(C).New!() error instantiating
Apparently, a class definition even inside a unittest blocks are
considered to be nested classes.
Normally, objects of nested classes are created by the 'this.new'
syntax, 'this' meaning the object that wraps the nested class.
class Outer
{
class Inner
{}
Inner makeInner()
{
return this.new Inner();
}
}
void main()
{
Outer o = new Outer;
Outer.Inner i = o.makeInner();
}
i contains a context pointer to its creators so that it can access the
outer object's members.
To make a nested class unnested, declare it as static, which seems to
work in your case as well:
class C { int x, y; }
auto x = New!C();
Ali
Re: is there any reason UFCS can't be used with 'new'?
On 09/30/2014 11:07 AM, Ali Çehreli wrote:
To make a nested class unnested, declare it as static, which seems to
work in your case as well:
class C { int x, y; }
auto x = New!C();
Copy+paste cannot read my mind. :( Of course there should be 'static'
keyword there. :p
static class C { int x, y; }
Ali
P.S. Shame! There is no mention of nested classes in my book. I put it
in my short to-do list.
Re: is there any reason UFCS can't be used with 'new'?
On 9/30/14 2:07 PM, Ali Çehreli wrote:
Apparently, a class definition even inside a unittest blocks are
considered to be nested classes.
Normally, objects of nested classes are created by the 'this.new'
syntax, 'this' meaning the object that wraps the nested class.
I think unit test blocks are actually functions disguised as attributes.
So it makes sense.
void foo()
{
class C {}
auto c = New!C; // same error
}
-Steve
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 22:17:03 UTC, Meta wrote: I'm not sure. Maybe it's on the same level as the Lambda Abstraction (14.5), but you'll probably have to do some testing to figure it out exactly. precedence levels seem to be defined in `src/parse.h` (the `PREC` enum) and assigned to operators in `src/parse.c` (`initPrecedence()`).
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 19:11:23 UTC, Jay wrote:
i want to chain 'new' with method calls on the created object.
i found this on the internet:
window.mainWidget = (new Button()).text(Hello
worldd).textColor(0xFF);
it would look much nicer with UFCS:
window.mainWidget = Button.new().text(Hello
worldd).textColor(0xFF);
well, it's not *exactly* UFCS but you get what i mean.
mixin template New(T) if (is(T == class)) {
static T New(Args...)(Args args) {
return new T(args);
}
}
class Bar {
string txt;
this() {
txt = Foo;
}
this(string t) {
txt = t;
}
mixin New!Bar;
}
void main() {
import std.stdio;
writeln(Bar.New().txt);
writeln(Bar.New(Bar).txt);
}
Re: is there any reason UFCS can't be used with 'new'?
thanks! but i'm still interested *why* you can't have this with
'new'. if there's no good reason i will file a bug report.
On Sunday, 28 September 2014 at 19:19:56 UTC, Foo wrote:
mixin template New(T) if (is(T == class)) {
static T New(Args...)(Args args) {
return new T(args);
}
}
class Bar {
string txt;
this() {
txt = Foo;
}
this(string t) {
txt = t;
}
mixin New!Bar;
}
void main() {
import std.stdio;
writeln(Bar.New().txt);
writeln(Bar.New(Bar).txt);
}
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 19:32:11 UTC, Jay wrote: thanks! but i'm still interested *why* you can't have this with 'new'. if there's no good reason i will file a bug report. Because `new` is not a function - it's an operator.
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 19:41:29 UTC, Idan Arye wrote: Because `new` is not a function - it's an operator. do you think the function call syntax has any chance to be implemented? is it just me who needs it?
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 19:19:56 UTC, Foo wrote:
mixin template New(T) if (is(T == class)) {
static T New(Args...)(Args args) {
return new T(args);
}
}
fwiw here's what i wrote:
template New(T) if (is(T == class)) {
T New(Args...) (Args args) {
return new T(args);
}
}
...
New!Bar(hi).txt.writeln;
not as neat as your version but still improves on the ugly (new
Class()).method syntax and doesn't need to be mixed into the
class definition.
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 19:11:23 UTC, Jay wrote:
i want to chain 'new' with method calls on the created object.
i found this on the internet:
window.mainWidget = (new Button()).text(Hello
worldd).textColor(0xFF);
it would look much nicer with UFCS:
window.mainWidget = Button.new().text(Hello
worldd).textColor(0xFF);
well, it's not *exactly* UFCS but you get what i mean.
The following code works perfectly fine. The precedence of the
`new` operator was changed in a release a year or two ago.
class Button
{
typeof(this) text(string t)
{
return this;
}
typeof(this) textColour(int c)
{
return this;
}
}
void main()
{
auto b = new Button()
.text(Hello, world!)
.textColour(0xFF00);
}
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 20:30:42 UTC, Meta wrote:
class Button
{
typeof(this) text(string t)
{
return this;
}
typeof(this) textColour(int c)
{
return this;
}
}
void main()
{
auto b = new Button()
.text(Hello, world!)
.textColour(0xFF00);
}
thanks! where should i put it in this table:
http://wiki.dlang.org/Operator_precedence ?
Re: is there any reason UFCS can't be used with 'new'?
On Sunday, 28 September 2014 at 20:50:07 UTC, Jay wrote:
On Sunday, 28 September 2014 at 20:30:42 UTC, Meta wrote:
class Button
{
typeof(this) text(string t)
{
return this;
}
typeof(this) textColour(int c)
{
return this;
}
}
void main()
{
auto b = new Button()
.text(Hello, world!)
.textColour(0xFF00);
}
thanks! where should i put it in this table:
http://wiki.dlang.org/Operator_precedence ?
I'm not sure. Maybe it's on the same level as the Lambda
Abstraction (14.5), but you'll probably have to do some testing
to figure it out exactly.
