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digitalmars.D.learn - method chaining

reply spir <denis.spir gmail.com> writes:
Hello,

I don't understand why the compiler refuses the code below, with the error
__trials__.d(33): found '.' when expecting ';' following statement
(Note that method set returns this.)

class C {
    int i,j;
    this (int i) {
        this.i =3D i;
    }
    C set (int j) {
        this.j =3D j;
        return this;
    }
    override string toString () {
        return format("C(%s,%s)", i,j);
    }
}

void main () {
    c =3D new C(1).set(3);	///////
    writeln(c);
}

Well, the example is somewhat artificial, but this idiom is highly useful.


Denis
-- -- -- -- -- -- --
vit esse estrany =E2=98=A3

spir.wikidot.com
Nov 08 2010
next sibling parent "Steven Schveighoffer" <schveiguy yahoo.com> writes:
On Mon, 08 Nov 2010 14:39:43 -0500, spir <denis.spir gmail.com> wrote:

 Hello,

 I don't understand why the compiler refuses the code below, with the  
 error
 __trials__.d(33): found '.' when expecting ';' following statement
 (Note that method set returns this.)

 class C {
     int i,j;
     this (int i) {
         this.i = i;
     }
     C set (int j) {
         this.j = j;
         return this;
     }
     override string toString () {
         return format("C(%s,%s)", i,j);
     }
 }

 void main () {
     c = new C(1).set(3);	///////

To the compiler, this means: c = new (C(1).set(3)); What you want is: c = (new C(1)).set(3); Java implies this, but D does not. -Steve
Nov 08 2010
prev sibling parent Tomek =?UTF-8?B?U293acWEc2tp?= <just ask.me> writes:
spir napisaƂ:

 Hello,
 
 I don't understand why the compiler refuses the code below, with the error
 __trials__.d(33): found '.' when expecting ';' following statement
 (Note that method set returns this.)
 
 class C {
     int i,j;
     this (int i) {
         this.i = i;
     }
     C set (int j) {
         this.j = j;
         return this;
     }
     override string toString () {
         return format("C(%s,%s)", i,j);
     }
 }
 
 void main () {
     c = new C(1).set(3);	///////
     writeln(c);
 }
 
 Well, the example is somewhat artificial, but this idiom is highly useful.

C c = (new C(1)).set(3); -- Tomek
Nov 08 2010