• typedef d.com (28/28) May 09 2005 Suppose a class has ctor defined, then a typedef-ed class cannot use tha...
• Thomas Kuehne (15/42) May 11 2005 -----BEGIN PGP SIGNED MESSAGE-----

typedef d.com writes:

Suppose a class has ctor defined, then a typedef-ed class cannot use that ctor:
------------------------------------------------------------   
class A { public
this(int param) {} }    
 
typedef A B;    
 
#void foo() {    
#  A a = new
A(0);  // OK    
#  B b = new B(0);  // error: cannot implicitly convert
expression    
#                   // (new A (0)) of type typedef.A to B    
#}
------------------------------------------------------------   
 
by contrast,
if no ctor defined in A, then it works:
------------------------------------------------------------   
class A {}
typedef A B;    
 
void foo() {   
A a = new A();  //OK   
B b = new B();  //OK
}   
------------------------------------------------------------   
 

Thomas Kuehne <thomas-dloop kuehne.thisisspam.cn> writes:

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Hash: SHA1

typedef d.com schrieb am Tue, 10 May 2005 02:00:09 +0000 (UTC):
 Suppose a class has ctor defined, then a typedef-ed class cannot use that ctor:
 ------------------------------------------------------------   
 class A { public
 this(int param) {} }    
  
 typedef A B;    
  
 #void foo() {    
 #  A a = new
 A(0);  // OK    
 #  B b = new B(0);  // error: cannot implicitly convert
 expression    
 #                   // (new A (0)) of type typedef.A to B    
 #}
 ------------------------------------------------------------   
  
 by contrast,
 if no ctor defined in A, then it works:
 ------------------------------------------------------------   
 class A {}
 typedef A B;    
  
 void foo() {   
 A a = new A();  //OK   
 B b = new B();  //OK
 }   
 ------------------------------------------------------------   

This is illegal code: http://digitalmars.com/d/class.html#constructors
# If there is no constructor for a class, but there is a constructor for
# the base class, a default constructor of the form:
#	this() { }
#	
# is implicitly generated.

Thomas


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