Questions tagged [library]

Libraries are reusable code. In the context of smart contracts, they are deployed only once at a specific address and their code is reused using DELEGATECALL.

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532 views

SafeMath library vs SafeMath contract on the inheritance chain

guys, I am developing ERC-20 token and I am wondering why SafeMath is used as as library in the OpenZeppelin implementation? Will not it be more optimal if we supply it as a base contract on the ...
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896 views

Can I define global variables in Library contract?

I want to use some variables in multiple functions in my library contract. Is there any way to do that? I got following error code for my library code. library myArithmetic { bytes1[10] mData; ...
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697 views

@dev and @title in solidity [duplicate]

When we use built-in library in solidity smart contract, why we need to use @dev and @title annotation? My code is like below: /** *@title SafeMath *@dev Math operations with safety checks that ...
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1answer
100 views

Is there an Ethereum javascript library to work with creating and validating addresses?

There are a bunch of ethereum sites with alot of js functionality already, but how did they do this when there is no js library that I can find? Is there a javascript library for working with Ethereum?...
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1answer
56 views

unable to understand how to use internal function types

I need help to understand below code which is from solidity offical documents "how to use internal function types". as it is very confusing for me. How to use library in solidity. Some one explain ...
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1answer
61 views

Why does this function not need a require statement?

Why does the following function not need a require statment? function transferFrom(address from, address to, uint256 value) public returns (bool) { _allowed[from][msg.sender] = _allowed[from][...
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1answer
400 views

Using a library to change storage

I'm trying to learn about using libraries in solidity. In the following test contract, swapNumberLib does not successfully set value1 = value2. I thought libraries could act on the storage of a ...
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1answer
379 views

Reputable Solidity utils library for arrays

Is there an audited and reputable smart contracts utils library with helpers for dealing with arrays? I haven't found anything great on Google so far.
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1answer
324 views

Library gets automatically included in contract

environment: all contracts use pragma solidity ^0.4.17; the compiler is 0.4.18+commit.9cf6e910.Emscripten.clang OS is MacOS X My token contract uses a Math library that is defined like so library ...
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1answer
887 views

link libraries with smart contracts

I have created library and imported in my contract. I am not able to link the library in deployment file. solution needed. thanks in adv pragma solidity ^0.4.2; library StringUtils { /// @dev ...
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1answer
393 views

Importing a contract from GitHub

I'm trying to import a contract from GitHub: pragma solidity ^0.4.18; pragma experimental ABIEncoderV2; pragma experimental "v0.5.0"; import "github.com/ethereum/dapp-bin/library/stringUtils.sol"; ...
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1answer
254 views

Solidity Library call gives Member not found or not visible after argument-dependent lookup

Using Solidity 0.4.17, I have defined a simple library at ./StringUtils.sol library StringUtils { function isEmptyString(string s) external pure returns (bool) { return (keccak256(s) == ...
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1answer
46 views

`vendor/` sub-directory relationship to 3rd party dependencies

In the -go-ethereum client directory I've run the command find . -name \*.md -print looking for README.md files. The output is as follows: ./.github/CONTRIBUTING.md ./.github/ISSUE_TEMPLATE....
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Ethereum linking library with contract not working as accepted…returning any state variable returns just the default value

my library pragma solidity ^0.5.8; library SafeMath { function add(uint256 a,uint256 b) public pure returns (uint256) { return a+b; } } My contract pragma solidity ^0.5.8; import ...
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Ethereum js wallet for php

https://github.com/ethereumjs/ethereumjs-wallet I need this library with the same functions in PHP Would u give me the link
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2answers
109 views

Is library use inherited?

When a base class uses a library, do derived classes also use the same library? For example: contract A { using SafeMath for uint256; ... } contract B is A { //is code here using ...
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How to use delegate call with external Library contract?

Here is my Library Contract deployed at 0xdeadbeef: library UsefulLib { function caculateAddress(address origin, uint nonce) pure external returns (address) { if(nonce == 0x00)...
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Understanding Solidity Libraries using Solidity Docs code example

I was going through this code (see code below) about how to use libraries in solidity docs : https://solidity.readthedocs.io/en/v0.4.24/contracts.html?highlight=library#libraries and there are some ...
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2answers
171 views

Publishing contracts with libraries using web3.py

Im trying to publish contracts with libraries in them and im getting the below issue. Contracts without libraries publish just fine. Can someone who might have faced this issue before advise what the ...
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187 views

How to verify a contract with libraries deployed from Remix

I successfully deployed a contract with remix here on Ropsten Testnet: https://ropsten.etherscan.io/address/0x10273a926517b417015748da21e1287bab2da8f7 The Source Code is very simple but I'm using my ...
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1answer
53 views

Using 3rd party libraries in production

In the case where you wish to use a library that someone else has written for your own contract, is it generally best practice to link to the developer's own deployment of their library? Or should you ...
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1answer
148 views

Library function access-level

I have a contract A, which has an instance of contract B, i.e., B b. Contract A calls a function of contract B via the instance, i.e., b.func(). Contract B is stateless, i.e., no global non-constant ...
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How to import libraries to Mist? [duplicate]

I've create a contract in Remix imporing 2 differents libreries and it works ok, but when I copy and paste it into Mist I got an error at the import statement. Code goes like this: pragma solidity ^...
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1answer
96 views

library, not found or visible after argument-dependent lookup in type

I am trying to understand libraries and I keep running in to "not found or visible after argument-dependent lookup in type". pragma solidity ^0.4.17; library L{ struct S{ uint UI; } ...
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1answer
68 views

How do types inherit from libraries?

When you're using a library like SafeMath, and then have using SafeMath for uint256; within a contract, how do uints know to become the a parameter of the library functions? Is that just a convention ...
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1answer
241 views

implement solidity library with no overhead of external function calls

When reading the doc of Solidity.I found out that the following is hard to understand or maybe I misunderstood something, any help is much appreciated.The document says: The following example shows ...
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1answer
531 views

Is there something like bitcore for Ethereum?

In Bitcoin there is a library named Bitcore. It helps abstract away a number of details, including using direct RPC commands. Is there something like Bitcore for Ethereum? Or do I need to use JSON-...
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206 views

Unable to retrieve struct from mapping

I have a mapping like this: pragma solidity 0.4.24; pragma experimental ABIEncoderV2; pragma experimental "v0.5.0"; ... mapping(bytes32 => LibMarket.Market) public hashToMarket; where each ...
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823 views

How does solidity online compiler link libraries?

Suppose I have this code: import "github.com/Arachnid/solidity-stringutils/strings.sol"; contract Contract { using strings for *; // ... } For this solidity online compiler generates this ...
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1answer
96 views

Solidity modifiers in library?

Isn't it possible to define modifiers in libraries? I'm really asking myself why, because thats some functionality you would need over and over again. If I would like to hypothetically implement some ...
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1answer
134 views

Payable function 'charges' sender twice value sent in tx after invoking library function

Facing a nasty bug and could really use a pair of fresh eyes. I have a payable function that is somehow taking twice the value sent to it by the sender, from the sender. Specifically, it appears to ...
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3answers
79 views

How to deploy Library contract separate from the main contract and link it

For deployment I am using remix. When I deploy Hello.sol the compiler typically merges SafeMath.sol as a part of the main contract (Hello.sol) and deploys. This adds up library and main contract's ...
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1answer
32 views

Can a library use another library?

Is it possible to use a library within a library? library L2 { //... } library L1 { using L2 for *; //... } This compiles and runs just fine but what I really want to know is if L1 is ...
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1answer
136 views

Trouble with libraries (Remix)

Tried out libraries for the first time, had a really bad experience with them. I need some help in getting my contracts to work between libraries. Library 1: pragma solidity ^0.4.0; library ...
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1answer
265 views

Error: invalid solidity type!: (library.enum)

Consider the following sample Truffle project: . ├── contracts │   ├── Foo.sol │   └── Migrations.sol ├── migrations │   ├── 1_initial_migration.js │   └── 2_foo.js ├── test │   └── Foo.test.js └── ...
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1answer
75 views

Building Ethereum application with in-process client

Most applications connect to an Ethereum Node through RPC, using a library like Web3.js and Nethereum. That introduces a need to deploy a full node side-by-side with the application, be it on the ...
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1answer
25 views

Workaround for testRPC bug where amounts spent multiple time with library calls?

Using testRPC the amount transferred is multiple times of the msg.value if a library call is involved. There is bug report and it was raised here and here as well. It's a well documented, long ...
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2answers
737 views

How would you install the Ethminer without sudo access?

I am trying to get Genoil's Ethminer installed on a machine without sudo access. The Github instructions require some packages to be installed. sudo apt-get install git cmake libcryptopp-dev ...
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1answer
90 views

Modifer Inheritance, Unexpected Result

The setup of the contracts has 3 contracts: a library contract, a Controller contract with modifiers and a main contract as follows: DataSet.sol library DataSet { struct IndexValue { uint ...
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1answer
22 views

pass storage through interface to library

Here is what am i doing: There is a library, accept storage argument as parameter, then do some math and return the result. And there is a contract to call the function in the library, and an extra ...
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1answer
13 views

Link library to contract without migrations

To link library in migrations I use: await deployer.deploy(MyTokenL) await deployer.link(MyTokenL, MyToken) We want to use migrations as infrastructure deployment and then have a deployment factory ...
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40 views

getting error error TypeError: Member “isContract” not found or not visible after argument-dependent lookup in address payable

Using Solidity 0.4.17, I have defined a simple library at ./Addresses.sol function isContract(address _base) external pure returns(bool) { assembly { _r := gt(extcodesize(_base), 0) ...
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1answer
162 views

Solidity SafeMath library best practice use cases

I understand why and how to use the SafeMath library. However, I was wondering if there is a kind of best practice guide how and when to use the library and in which cases you don't have to. From a ...
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1answer
194 views

Upradeable proxy library throws on any function, how to connect proxy and maincontract

I'm trying to implement a proxy library through the techniques researched by openZeppelin using proxies. I have 4 contracts 1. Library with logic 2. Library containing the interface for the logic ...
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1answer
161 views

OpenZeppelin ECRecovery does not work

I am trying to use the OpenZeppelin ECRecovery library for a project I am working on. Unfortunately I don't fully understand how it works and there's no documentation for it. Let's say I want to ...
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1answer
126 views

Contract libraries structure

I have pretty big smart contract with a lot of structs. Each struct has in average 3-4 related methods (i.e. methods with first parameter MyLibrary.MyType storage self). Question about code ...