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jguo
jguo

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Learning Golang 105

#go #beginners

Custom Type and Receiver

define a type

type deck []string
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receiver

fun (d deck) print() { for i, card := range d { fmt.Printf(i, card) } }
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call print func

d := deck{"card1", "card2"} d.print()
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You can see that adding a receiver to a custom type, it extends the type's functionality.

Type assertions

A type assertion takes an interface value and extracts from it a value of the specified explicit type.
For example

res, ok := deck.([]string) if ok { fmt.Printf("slice value is: %q\n", res) } else { fmt.Printf("value is not a slice\n") }
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Structs

define a struct

type person struct { firstName string lastName string }
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declare a struct

// alex := person{"Alex", "Anderson"} //rely on order. alex := person{firstName: "Alex", lastName: "Anderson"} alex.firstName = "Alex"
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Pointers

Go passes by value. It creates a copy when you pass a value.
& give the address of a value
* give the value of an address or define a pointer.

Turn address into value with *address.
Turn value into address with &value.

Value Types Reference Types
int slices
float maps
string channels
bool points
structs functions

when passing a reference type, go still make a copy, but reference type is a reference. So, it is like passing by reference.

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