139 lines
2.8 KiB
ReStructuredText
139 lines
2.8 KiB
ReStructuredText
Configuring & Using Contracts
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===============
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Embark will automatically take care of deployment for you and set all
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needed JS bindings. For example, the contract below:
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.. code:: javascript
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# app/contracts/simple_storage.sol
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contract SimpleStorage {
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uint public storedData;
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function SimpleStorage(uint initialValue) {
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storedData = initialValue;
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}
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function set(uint x) {
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storedData = x;
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}
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function get() constant returns (uint retVal) {
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return storedData;
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}
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}
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Will automatically be available in Javascript as:
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.. code:: javascript
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# app/js/index.js
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SimpleStorage.set(100);
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SimpleStorage.get().then(function(value) { console.log(value.toNumber()) });
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SimpleStorage.storedData().then(function(value) { console.log(value.toNumber()) });
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You can specify for each contract and environment its gas costs and
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arguments:
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.. code:: json
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# config/contracts.json
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{
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"development": {
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"gas": "auto",
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"contracts": {
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"SimpleStorage": {
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"args": [
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100
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]
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}
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}
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}
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}
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If you are using multiple contracts, you can pass a reference to another
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contract as ``$ContractName``, Embark will automatically replace this
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with the correct address for the contract.
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.. code:: json
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# config/contracts.json
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{
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...
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"development": {
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"contracts": {
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"SimpleStorage": {
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"args": [
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100,
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"$MyStorage"
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]
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},
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"MyStorage": {
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"args": [
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"initial string"
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]
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},
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"MyMainContract": {
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"args": [
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"$SimpleStorage"
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]
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}
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}
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}
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...
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}
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You can now deploy many instances of the same contract. e.g
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.. code:: json
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# config/contracts.json
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{
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"development": {
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"contracts": {
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"Currency": {
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"deploy": false,
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"args": [
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100
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]
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},
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"Usd": {
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"instanceOf": "Currency",
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"args": [
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200
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]
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},
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"MyCoin": {
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"instanceOf": "Currency",
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"args": [
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200
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]
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}
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}
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}
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}
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...
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Contracts addresses can be defined, If an address is defined the
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contract wouldn't be deployed but its defined address will be used
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instead.
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.. code:: json
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# config/contracts.json
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{
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...
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"development": {
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"contracts": {
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"UserStorage": {
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"address": "0x123456"
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},
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"UserManagement": {
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"args": [
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"$UserStorage"
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]
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}
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}
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}
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...
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}
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