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Merge pull request #1411 from ethereum/function-type-docs

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Fix function type examples
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Yoichi Hirai 2016-11-23 11:34:40 +01:00 committed by GitHub
commit 475009b93d
1 changed files with 18 additions and 8 deletions
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docs/types.rst
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@ -312,12 +312,19 @@ If external function types are used outside of the context of Solidity,
they are treated as the ``function`` type, which encodes the address they are treated as the ``function`` type, which encodes the address
followed by the function identifier together in a single ``bytes24`` type. followed by the function identifier together in a single ``bytes24`` type.
Note that public functions of the current contract can be used both as an
internal and as an external function. To use ``f`` as an internal function,
just use ``f``, if you want to use its external form, use ``this.f``.
Example that shows how to use internal function types:: Example that shows how to use internal function types::
pragma solidity ^0.4.5;
library ArrayUtils { library ArrayUtils {
// internal functions can be used in internal library functions because // internal functions can be used in internal library functions because
// they will be part of the same code context // they will be part of the same code context
function map(uint[] memory self, function (uint) returns (uint) f) function map(uint[] memory self, function (uint) returns (uint) f)
internal
returns (uint[] memory r) returns (uint[] memory r)
{ {
r = new uint[](self.length); r = new uint[](self.length);
@ -327,8 +334,9 @@ Example that shows how to use internal function types::
} }
function reduce( function reduce(
uint[] memory self, uint[] memory self,
function (uint) returns (uint) f function (uint x, uint y) returns (uint) f
) )
internal
returns (uint r) returns (uint r)
{ {
r = self[0]; r = self[0];
@ -336,7 +344,7 @@ Example that shows how to use internal function types::
r = f(r, self[i]); r = f(r, self[i]);
} }
} }
function range(uint length) returns (uint[] memory r) { function range(uint length) internal returns (uint[] memory r) {
r = new uint[](length); r = new uint[](length);
for (uint i = 0; i < r.length; i++) { for (uint i = 0; i < r.length; i++) {
r[i] = i; r[i] = i;
@ -346,7 +354,7 @@ Example that shows how to use internal function types::
contract Pyramid { contract Pyramid {
using ArrayUtils for *; using ArrayUtils for *;
function pyramid(uint l) return (uint) { function pyramid(uint l) returns (uint) {
return ArrayUtils.range(l).map(square).reduce(sum); return ArrayUtils.range(l).map(square).reduce(sum);
} }
function square(uint x) internal returns (uint) { function square(uint x) internal returns (uint) {
@ -359,14 +367,16 @@ Example that shows how to use internal function types::
Another example that uses external function types:: Another example that uses external function types::
pragma solidity ^0.4.5;
contract Oracle { contract Oracle {
struct Request { struct Request {
bytes data; bytes data;
function(bytes) external callback; function(bytes memory) external callback;
} }
Request[] requests; Request[] requests;
event NewRequest(uint); event NewRequest(uint);
function query(bytes data, function(bytes) external callback) { function query(bytes data, function(bytes memory) external callback) {
requests.push(Request(data, callback)); requests.push(Request(data, callback));
NewRequest(requests.length - 1); NewRequest(requests.length - 1);
} }
@ -377,12 +387,12 @@ Another example that uses external function types::
} }
contract OracleUser { contract OracleUser {
Oracle constant oracle = 0x1234567; // known contract Oracle constant oracle = Oracle(0x1234567); // known contract
function buySomething() { function buySomething() {
oracle.query("USD", oracleResponse); oracle.query("USD", this.oracleResponse);
} }
function oracleResponse(bytes response) { function oracleResponse(bytes response) {
if (msg.sender != oracle) throw; if (msg.sender != address(oracle)) throw;
// Use the data // Use the data
} }
} }