igl42 / cpp_software_design Goto Github PK

Hi, I have learned a lot from your book, but in guideline 4 I have two questions:1. should the “widgetDetails::BlobCollection blobs_” in wideget class be “widgetDetails::BlobCollection::blobs_” ,and if the blobs_ is a class, then does it introduce a new dependency? 2. After extracting the Blobcollection class, I rather don't quite understand how to use the widget class, and how to use the BlobCollection class to test，may you show me an example,thanks!

This is main function comments

// 7% tax: 19*1.07 = 20.33
// 20% discount, 19% tax: (999*0.8)*1.19 = 951.05

And output format is followings.

std::ostream& operator<<( std::ostream& os, Money money )
{
   return os << money.value;
}

So, I think output type is 'value' field type. Then 'value' field type is uint64_t.

If main comments is collect, it should change uint64_t to double(or float).

In session : An owning type erasure implemention
this code can not compile at this line : Shape shape( drawingCircle );

Am I need to change the implemention of Shape Class ?

//---- <YourMain.cpp> ----------------

int main()
{
// Create a circle as one representative of a concrete shape type
Circle circle{ 3.14 };

// Bind the circle to some drawing functionality
auto drawingCircle = = { myCircleDrawer(circle); };

// Type-erase the circle equipped with drawing behavior
Shape shape( drawingCircle );

// Drawing the shape
draw( shape );

// ...

return EXIT_SUCCESS;
}