//Func is a C# builit in delegate that takes (many - 16, arguments and returns a value - out)
//in the use below, we pass in a List of ProductModel, the subTotal and we expect an out (return value).
//and we name (give an alias - not too sure is saying alias is correct, but doing so for my understanding) so this Func<T> is easier to use.
//I also use the type Action. Also a built in C# Delegate but an Action dosn't have a return type.
//Tim Corey mentions that normally, Func and Action would not be used in this way, but this is a Delegate Demo App and so lets show C# Delegates in use.
public decimal GenerateTotal(MentionDiscount mentionSubTotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal,
Action <string> tellUserWeAreDiscounting)
{
//throw new NotImplementedException();
//Use delegate.
decimal subTotal = Items.Sum(x => x.Price);
mentionSubTotal(subTotal);
tellUserWeAreDiscounting("We are applying your discount");
////Calculate Discount depending on amount of purchase
////These hard code values are bad practice. It leads to violating the Open Close Principal
//if(subTotal > 100)
//{
// return subTotal * 0.80M;
//}
//else if(subTotal > 50)
//{
// return subTotal * 0.85M;
//}
//else if(subTotal > 10)
//{
// return subTotal * 0.90M;
//}
//else
//{
// return subTotal;
//}
decimal total = calculateDiscountedTotal(Items, subTotal);
return(total);
}
public decimal GenerateTotal(MentionDiscount mentionDiscount, DiscountTotal calculateDiscount, MessageShow tellUserWeAreDiscounting)
{
decimal subTotal = Items.Sum(x => x.Price);
mentionDiscount(subTotal);
tellUserWeAreDiscounting("We are applying discount");
return(calculateDiscount(Items, subTotal));
}
public decimal GenerateTotal(MentionDiscount mentionDiscount, Func <List <ProductModel>, decimal, decimal> calculateDiscount, Action <string> tellUserWeAreDiscounting)
{
decimal subTotal = Items.Sum(x => x.Price);
mentionDiscount(subTotal);
tellUserWeAreDiscounting("We are applying your discount");
return(calculateDiscount(Items, subTotal));
}
public decimal GenerateTotal(MentionDiscount mentionSubtotal, Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal, Action <string> tellUserWeAreDiscounting)
{
decimal subTotal = Items.Sum(item => item.Price);
mentionSubtotal(subTotal);
tellUserWeAreDiscounting("We are applying discount.");
return(calculateDiscountedTotal(Items, subTotal));
}
public decimal GenerateTotal(MentionDiscount mentionSubtotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal,
Action <string> mentionToUserDiscount)
{
decimal subTotal = Items.Sum(x => x.Price);
mentionSubtotal(subTotal);
mentionToUserDiscount("Discounting...");
return(calculateDiscountedTotal(Items, subTotal));
}
public decimal TotalItems(MentionDiscount mentionSubtotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal, Action <string> mentionDiscounting)
{
decimal subTotal = Items.Sum(x => x.Price);
mentionSubtotal(subTotal);
mentionDiscounting("We are applying your discount");
return(calculateDiscountedTotal(Items, subTotal));
}
public decimal GenerateTotal(MentionDiscount mentionDiscount,
Func <List <ProductModel>, decimal, decimal> calculateDiscountTotal,
Action <string> showDiscounting)
{
decimal subtotal = Items.Sum(x => x.Price);
mentionDiscount(subtotal);
showDiscounting("We are applying discounts");
return(calculateDiscountTotal(Items, subtotal));
}
//passing in the arbitrary delegate method
public decimal GenerateTotal(MentionDiscount mentionSubtotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountetTotal, //Func returns a value
Action <string> tellUserWeAreDiscounting) //Action returns a void
{
decimal subTotal = Items.Sum(x => x.Price);
mentionSubtotal(subTotal); // calling the method mentionDiscount and passing in the subTotal (loosly coupled, because genrateTotal doesnt know anything about mentionDiscount).
tellUserWeAreDiscounting("We are applying your discount.");
return(calculateDiscountetTotal(Items, subTotal));
}
public decimal GenerateTotal(MentionDiscount mentionSubtotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal,
Action <string> tellUserWeAreDicounting)
{
var subtotal = Items.Sum(i => i.Price);
mentionSubtotal(subtotal);
tellUserWeAreDicounting("Aplicando desconto");
return(calculateDiscountedTotal(Items, subtotal));
}
public decimal GenerateTotal(MentionDiscount mentionSubtotal,
/*
* Func has 16 overloads. In Func we can pass 16 different variables, if that's the case you are back to creating a delegate. It is one of the limitations
* for this simplicity model. We cannot name these things we just have to pass in the types. So, Func takes in 16 parameters and the last parameter is
* always the output. Func is a method that has a return value other than void. Func does not work with out parameters. If you have to do that you have to
* use a delegate.
*/
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal,
/*
* Action does not returns a value, it returns a void.
*/
Action <string> tellUserWeAreDiscounting)
{
/*
* The Sum method below is actually taking a Func of ProductModel and decimal. So, it is using a delegate called Func. And, it is one delegate where
* x is our ProductModel and we are passing in and saying take the price for each of them and add them together.
*/
decimal subTotal = Items.Sum(x => x.Price);
/*
* Something is not good with this method because we have a whole bunch of hard-coded items and that's not really wise. Because this library may be used
* by different applications in your company. If you have to recompile this library with new code that means you have to change all your applications by
* recompiling them and redeploying them and that's really not efficient.
*
* if (subTotal > 100)
* {
* return subTotal * 0.80M;
* }
* else if (subTotal > 50)
* {
* return subTotal * 0.85M;
* }
* else if (subTotal > 10)
* {
* return subTotal * 0.95M;
* }
* else
* {
* return subTotal;
* }
*/
mentionSubtotal(subTotal);
tellUserWeAreDiscounting("We are applying your discount.");
return(calculateDiscountedTotal(Items, subTotal));
}
/// <summary>
/// Generate total sum
/// * Creating anonymous methods: anonymous Delegate
/// * Creating anonymous methods: anonymous Func
/// * Creating anonymous methods: anonymous Action
/// </summary>
/// <param name="mentionSubtotal"></param>
/// <param name="calculateDiscountedTotal"></param>
/// <param name="tellUserWeAreDiscounting"></param>
/// <returns></returns>
public decimal GenerateTotal(MentionDiscount mentionSubtotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal,
Action <string> tellUserWeAreDiscounting)
{
decimal subTotal = Products.Sum(product => product.Price);
// Use delegate method
mentionSubtotal?.Invoke(subTotal);
// Use Action method
tellUserWeAreDiscounting?.Invoke("We are applying your discount.");
// Use Func method
return(calculateDiscountedTotal?.Invoke(Products, subTotal) ?? 0);
}
public decimal GenerateTotal(MentionDiscount mentionDiscount,
Func <List <ProductModel>, decimal, decimal> calculateDiscountTotal,
Action <string> informUserApplyDiscount)
{
decimal subtotal = Items.Sum(x => x.Price);
decimal returnVal;
mentionDiscount(subtotal);
informUserApplyDiscount("Applying discount...");
returnVal = calculateDiscountTotal(Items, subtotal);
mentionDiscount(subtotal - returnVal);
return(returnVal);
}
// ""Func<> method"" takes "List<ProductModel>" and one "decimal" value as input,
// last one "decimal" is output.
// With using Func<> we dont need to use signature like we did for MentionDiscount
public decimal GenerateTotal(MentionDiscount mentionSubtotal,
Func <List <ProductModel>, decimal, decimal> calculateDiscountedTotal,
Action <string> tellUserWeAreDiscounting)
{
decimal subTotal = Items.Sum(x => x.Price);
mentionSubtotal(subTotal);
tellUserWeAreDiscounting("applying discount...");
// Only send two paramater. last paramater of calculateDiscountedTotal
// is output(decimal)
decimal total = calculateDiscountedTotal(Items, subTotal);
return(total);
// Func is a delegate that points to a method that accepts one or more
// arguments and returns a value. Action is a delegate that points to a method
// which in turn accepts one or more arguments but returns no value. In other words,
// you should use Action when your delegate points to a method that returns void.
}
public decimal GenerateTotal(MentionDiscount mentionDiscount)
{
decimal subTotal = items.Sum(x => x.Price);
mentionDiscount(subTotal);
if (subTotal > 100)
{
return(subTotal * 0.80M);
}
else if (subTotal > 50)
{
return(subTotal * 0.85M);
}
else if (subTotal > 10)
{
return(subTotal * 0.90M);
}
else
{
return(subTotal);
}
}
