Thrift language


Type

The thrift type system consists of predefined base types, containers, user defined struct, enum and exception


Base type and containers

/**
 * The available types in Thrift are:
 *
 *  bool        Boolean, one byte
 *  byte        Signed byte
 *  i16         Signed 16-bit integer
 *  i32         Signed 32-bit integer
 *  i64         Signed 64-bit integer
 *  double      64-bit floating point value
 *  string      String
 *  map<t1,t2>  Map from one type to another
 *  list<t1>    Ordered list of one type
 *  set<t1>     Set of unique elements of one type
 *
 */


User defined types

/**
 * You can define enums, which are just 32 bit integers. Values are optional.
 * If no constant value is supplied, the value is either 0 for the
 * first element, or one greater than the preceding value for any subsequent element.
 */
enum Operation {
  ADD = 1,
  SUBTRACT = 2,
  MULTIPLY = 3,
  DIVIDE = 4
}

/**
 * Structs are the basic complex data structures. They are comprised of fields
 * which each have an integer identifier, a type, a symbolic name, and an
 * optional default value.
 *
 * Fields can be declared "optional", which ensures they will not be included
 * in the serialized output if they aren't set.
 */
struct Work {
  1: i32 num1 = 0,
  2: i32 num2,
  3: Operation op,
  4: optional string comment,
}

/**
 * Exception is defined in simiar way as struct.
 */
exception InvalidOperation {
  1: i32 what,
  2: string why
}


Defining service

/**
 * Services just need a name and can optionally inherit
 * from another service using the extends keyword.
 */
service Calculator extends shared.SharedService {

  /**
   * A method definition looks like C code. It has a return type, arguments,
   * and optionally a list of exceptions that it may throw. Note that argument
   * lists and exception lists are specified using the exact same syntax as
   * field lists in struct or exception definitions.  NOTE: Overloading of
   * methods is not supported; each method requires a unique name.
   */

   void ping(),

   i32 add(1:i32 num1, 2:i32 num2),

   i32 calculate(1:i32 logid, 2:Work w) throws (1:InvalidOperation ouch),

   /**
    * This method has an oneway modifier. That means the client only makes
    * a request and does not listen for any response at all. Oneway methods
    * must be void.
    *
    * The server may execute async invocations of the same client in parallel/
    * out of order.
    */
   oneway void zip(),
}


Misc

/* Thrift supports C style comments?
 */

// Thirft also support simple C comments too.

/**
 * Thrift files can reference other Thrift files to include common struct
 * and service definitions. These are found using the current path, or by
 * searching relative to any paths specified with the -I compiler flag.
 *
 * Included objects are accessed using the name of the .thrift file as a
 * prefix. i.e. shared.SharedObject
 */
include "shared.thrift"

/**
 * Thrift files can namespace, package, or prefix their output in various
 * target languages.
 */
namespace cpp tutorial
namespace java tutorial
php_namespace tutorial
namespace perl tutorial
namespace smalltalk.category Thrift.Tutorial

/**
 * Thrift lets you do typedefs to get pretty names for your types. Standard
 * C style here.
 */
typedef i32 MyInteger

/**
 * Thrift also lets you define constants for use across languages. Complex
 * types and structs are specified using JSON notation.
 */
const i32 INT32CONSTANT = 9853
const map<string,string> MAPCONSTANT = {'hello':'world', 'goodnight':'moon'}

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