Go Concepts - Functions: Difference between revisions
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=The <tt>main()</tt> Function= | |||
=Built-in Functions= | =Built-in Functions= |
Revision as of 06:46, 22 March 2016
External
- Function type specification https://golang.org/ref/spec#Function_types
Internal
Function Definition
A function declaration starts with the func keyword and it consists in a series of statements applied on a number of inputs, resulting in a number of outputs. Same inputs will always result in the same outputs. Function do not depend on a type instance's state. From this perspective, functions are conceptually different from methods.
Syntax
func <name>( [parameter-identifier1] [type1], [parameter-identifier2] [type2], ...) [( <return-type1>, [return-type2], ...)] { // function's body statement1 statement2 ... return <return-value1>, <return-value2> }
The return type declarations are optional, if the function does not return anything.
A function may return one or more results.
Examples:
func add(a int, b int) (int) { return a + b; }
The main() Function
Built-in Functions
make() | append() | copy() | delete() | . |
new() | len() | cap() | . | . |
. | . | . | . | . |
Closures
Anonymous function that capture local variables.
More about closures is available here.
Methods
A method defines the behavior of a type, and it relies on the state of an instance of the type. The method will - and it is supposed to - change the state. From this point of view, the method is conceptually different from a function.
A method is always exported by the package it is enclosed in.
Syntax
func <receiver> <method-name> (...) { // the rest of declaration is similar to a function's ... }