Shulou(Shulou.com)06/01 Report--

This article mainly explains "how to import other source files in Solidity". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how to import other source files in Solidity".

Solidity source file

The source file consists of contract definitions, instructions, and compilation instructions.

Compiled version tag

The source file should specify a compiled version, which has prevented the source file from being used in subsequent incompatible compilers. We try to ensure that the code is compatible with the compiler as much as possible, but this is sometimes impossible. So you can query the update log to understand the differences between versions. These releases are marked with a version number in the form of 0.x.0 or x.0.0

Example of version directive:

Pragma solidity ^ 0.4.0

The above tag indicates that the file cannot be used in versions prior to 0.4.0 and cannot be used in version 0.5.0. Indicates that it can be used under each version of 4.0.

Multiple applicable versions can be specified through npm.

Import syntax and semantics of other source files

Solidity supports import import statements similar to JS, but does not support the "default export" feature.

At the global level, you can use the import statement as follows

Import "filename"

This import statement imports all symbols from the file into the global space.

Import * as symbolName from "filename"

Generate a new global name symbolName to bring in all symbols from the file.

Import {symbol1 as alias, symbol2} from "filename"

Bring in symbol1 and symbol2 in the file and rename symbol1 to alias.

The following syntax is not supported by ES6, but is easier to use:

Import "filename" as symbolName

This is equivalent to

Import * as symbolName from "filename"; path

As shown above, fileName uses "/" as the path separator, "." Represents the current path. ".." Represents the parent path. When "." And ".." When followed by "/", it is not considered to be the current path or the parent path. If the path is not "." And ".." At the beginning, then this path is considered absolute.

Import file x from the current path, using import ". / x" as x. If you use import "x" as x; then the file is imported from the global path.

The import file depends on how the compiler actually maps the path, which usually maps not only to the local system, but also to other channels such as ipfs, http or git, and so on.

True compilation

When the compiler is called, the compiler can not only reference the elements in the path, but also map the path github.com/ethereum/dapp-bin/library to the local / usr/local/dapp-bin/library, and can read the files in it. If multiple mappings are allowed, the longest Key will be tried. Can be "recursive mapping" for example. "map to" / usr/local/include/solidity ". In addition, remapping can map different versions of packages to the same name based on the current context.

Thank you for your reading, the above is the content of "how to import other source files in Solidity". After the study of this article, I believe you have a deeper understanding of how to import other source files in Solidity. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.