Pointer to a map
Maps are reference types, so they are always passed by reference. You don’t need a pointer. Go Doc
pointers
Understanding and relationship between Box, ref, & and *
First of all, all of the items you listed are really different things, even if they are related to pointers. Box is a library-defined smart pointer type; ref is a syntax for pattern matching; & is a reference operator, doubling as a sigil in reference types; * is a dereference operator, doubling as a sigil … Read more
In Go HTTP handlers, why is the ResponseWriter a value but the Request a pointer?
What you get for w is a pointer to the non exported type http.response but as ResponseWriter is an interface, that’s not visible. From server.go: type ResponseWriter interface { … } On the other hand, r is a pointer to a concrete struct, hence the need to pass a reference explicitly. From request.go: type Request … Read more
What’s the point of having pointers in Go?
Pointers are usefull for several reasons. Pointers allow control over memory layout (affects efficiency of CPU cache). In Go we can define a structure where all the members are in contiguous memory: type Point struct { x, y int } type LineSegment struct { source, destination Point } In this case the Point structures are … Read more
Range references instead values
The short & direct answer: no, use the array index instead of the value So the above code becomes: package main import “fmt” type MyType struct { field string } func main() { var array [10]MyType for idx, _ := range array { array[idx].field = “foo” } for _, e := range array { fmt.Println(e.field) … Read more
What is a “fat pointer”?
The term “fat pointer” is used to refer to references and raw pointers to dynamically sized types (DSTs) – slices or trait objects. A fat pointer contains a pointer plus some information that makes the DST “complete” (e.g. the length). Most commonly used types in Rust are not DSTs but have a fixed size known … Read more
” is pointer to interface, not interface” confusion
So you’re confusing two concepts here. A pointer to a struct and a pointer to an interface are not the same. An interface can store either a struct directly or a pointer to a struct. In the latter case, you still just use the interface directly, not a pointer to the interface. For example: type … Read more
How do I do a literal *int64 in Go?
The Go Language Specification (Address operators) does not allow to take the address of a numeric constant (not of an untyped nor of a typed constant). The operand must be addressable, that is, either a variable, pointer indirection, or slice indexing operation; or a field selector of an addressable struct operand; or an array indexing … Read more
X does not implement Y (… method has a pointer receiver)
This compile-time error arises when you try to assign or pass (or convert) a concrete type to an interface type; and the type itself does not implement the interface, only a pointer to the type. Short summary: An assignment to a variable of interface type is valid if the value being assigned implements the interface … Read more
Pointers vs. values in parameters and return values
tl;dr: Methods using receiver pointers are common; the rule of thumb for receivers is, “If in doubt, use a pointer.” Slices, maps, channels, strings, function values, and interface values are implemented with pointers internally, and a pointer to them is often redundant. Elsewhere, use pointers for big structs or structs you’ll have to change, and … Read more