digitalmars.D.learn - Tools for building a dynamic derived type? I need a push in the right
- Gary Willoughby (57/57) Aug 20 2013 I've been researching ways to accomplish creating a template that
- Kapps (12/69) Aug 20 2013 AutoImplement
- Gary Willoughby (2/89) Sep 07 2013 Thanks that gave me a lot to work with! :)
- Jacob Carlborg (8/22) Aug 20 2013 I'm not exactly sure how you want it to work, but this is an idea:
I've been researching ways to accomplish creating a template that
creates a special kind of derived type and i think i need a push
in the right direction. Take this simple class:
class Person
{
private string _name;
private int _age;
this(string name, int age)
{
this._name = name;
this._age = age;
}
public string getName()
{
return this._name;
}
public int getAge()
{
return this._age;
}
}
I want to create a mock of this class which would mean achieving
the following:
1). Extend the class
2). Override all public methods to do nothing (or look for
enabled methods)
3). Provide a way of dynamically enabling methods with new return
values
Extending the class is pretty easy and adding methods dynamically
looks to be solved (TDPL 12.11.1) but it's the override all
public methods to do something different which is beating me. I
know it will probably involve mixins and dealing with tuples
somewhere along the line but documentation is lacking everywhere
i look.
std.traits gives me information about a type but using that
information is where i need the documentation. e.g. i know the
traits methods return tuples but how do you work with these
tuples? how to Iterate through them? I seem to always get stuck
when trying to iterate through tuples and generate compiler
errors.
I've taken a look at the std.typecons source especially BlackHole
and WhiteHole templates but i get lost. They are almost doing
what i want but for abstract methods.
The general usage is probably going to be something like this:
class Mock(T) : T
{
// Implementation
}
auto cat = Mock!Cat("Ginger"); // constructors supported.
auto person = Mock!Person();
person.addMethod("getName", delegate(){
return "Foo";
});
person.addMethod("getAge", delegate(){
return 10;
});
Any help will be greatly appreciated.
Aug 20 2013
On Tuesday, 20 August 2013 at 18:55:44 UTC, Gary Willoughby wrote:
I've been researching ways to accomplish creating a template
that creates a special kind of derived type and i think i need
a push in the right direction. Take this simple class:
class Person
{
private string _name;
private int _age;
this(string name, int age)
{
this._name = name;
this._age = age;
}
public string getName()
{
return this._name;
}
public int getAge()
{
return this._age;
}
}
I want to create a mock of this class which would mean
achieving the following:
1). Extend the class
2). Override all public methods to do nothing (or look for
enabled methods)
3). Provide a way of dynamically enabling methods with new
return values
Extending the class is pretty easy and adding methods
dynamically looks to be solved (TDPL 12.11.1) but it's the
override all public methods to do something different which is
beating me. I know it will probably involve mixins and dealing
with tuples somewhere along the line but documentation is
lacking everywhere i look.
std.traits gives me information about a type but using that
information is where i need the documentation. e.g. i know the
traits methods return tuples but how do you work with these
tuples? how to Iterate through them? I seem to always get stuck
when trying to iterate through tuples and generate compiler
errors.
I've taken a look at the std.typecons source especially
BlackHole and WhiteHole templates but i get lost. They are
almost doing what i want but for abstract methods.
The general usage is probably going to be something like this:
class Mock(T) : T
{
// Implementation
}
auto cat = Mock!Cat("Ginger"); // constructors supported.
auto person = Mock!Person();
person.addMethod("getName", delegate(){
return "Foo";
});
person.addMethod("getAge", delegate(){
return 10;
});
Any help will be greatly appreciated.
AutoImplement
std.typecons should do what you want. Instead of implementing
only abstract methods, you could make it implement all non-final
methods by changing the 'what' template parameter to simply
return true (final methods are skipped regardless). Then you
could change the 'how' template parameter to return
ReturnType!parent.init unless an argument is set in an AA. I
can't say I've ever tried this though, so I'm not sure how well
it would work in reality.
https://github.com/QAston/DMocks-revived may interest you as well.
Aug 20 2013
"Gary Willoughby" <dev nomad.so> On Wednesday, 21 August 2013 at 03:37:46 UTC, Kapps wrote:On Tuesday, 20 August 2013 at 18:55:44 UTC, Gary Willoughby wrote:Thanks that gave me a lot to work with! :)I've been researching ways to accomplish creating a template that creates a special kind of derived type and i think i need a push in the right direction. Take this simple class: class Person { private string _name; private int _age; this(string name, int age) { this._name = name; this._age = age; } public string getName() { return this._name; } public int getAge() { return this._age; } } I want to create a mock of this class which would mean achieving the following: 1). Extend the class 2). Override all public methods to do nothing (or look for enabled methods) 3). Provide a way of dynamically enabling methods with new return values Extending the class is pretty easy and adding methods dynamically looks to be solved (TDPL 12.11.1) but it's the override all public methods to do something different which is beating me. I know it will probably involve mixins and dealing with tuples somewhere along the line but documentation is lacking everywhere i look. std.traits gives me information about a type but using that information is where i need the documentation. e.g. i know the traits methods return tuples but how do you work with these tuples? how to Iterate through them? I seem to always get stuck when trying to iterate through tuples and generate compiler errors. I've taken a look at the std.typecons source especially BlackHole and WhiteHole templates but i get lost. They are almost doing what i want but for abstract methods. The general usage is probably going to be something like this: class Mock(T) : T { // Implementation } auto cat = Mock!Cat("Ginger"); // constructors supported. auto person = Mock!Person(); person.addMethod("getName", delegate(){ return "Foo"; }); person.addMethod("getAge", delegate(){ return 10; }); Any help will be greatly appreciated.AutoImplement std.typecons should do what you want. Instead of implementing only abstract methods, you could make it implement all non-final methods by changing the 'what' template parameter to simply return true (final methods are skipped regardless). Then you could change the 'how' template parameter to return ReturnType!parent.init unless an argument is set in an AA. I can't say I've ever tried this though, so I'm not sure how well it would work in reality. https://github.com/QAston/DMocks-revived may interest you as well.
Sep 07 2013
On 2013-08-20 20:55, Gary Willoughby wrote:
The general usage is probably going to be something like this:
class Mock(T) : T
{
// Implementation
}
auto cat = Mock!Cat("Ginger"); // constructors supported.
auto person = Mock!Person();
person.addMethod("getName", delegate(){
return "Foo";
});
person.addMethod("getAge", delegate(){
return 10;
});
Any help will be greatly appreciated.
I'm not exactly sure how you want it to work, but this is an idea:
Create and store an instance of T in Mock. Implement opDispatch in Mock
and forward an methods added by addMethod to the delegate. If no
delegate exists for that method forward to the instance of T instead.
http://dlang.org/operatoroverloading.html#Dispatch
--
/Jacob Carlborg
Aug 20 2013