golang_modules_tool_notes.txt

Golang Modules and Tools

Basic Tools in Go
1. go build
   - Builds the application into a single binary, including all required packages.
2. go run
   - Executes a Go file directly, combining compilation and execution in one step.

Initializing a Module
- go mod init <module_name>
  - Initializes a new module. The module name should follow the format:
    hosting-platform/username/project-name
    Example:
    github.com/AdityaByte/mymodules

Note:
Refer to semver.org to understand versioning standards.

Managing Dependencies
1. go get
   - Fetches dependencies from the web.
     Example:
     go get -u github.com/gorilla/mux

     - -u: Updates the dependency to the latest minor or patch version.

   Note:
   - If a dependency is marked as indirect, it means it was added but isn't used directly in the code.

2. go mod tidy
   - Cleans up unused dependencies and organizes the go.mod file.
   - Removes indirect dependencies if they aren't used.

3. go mod verify
   - Verifies the integrity of module downloads by checking hash values.
     Output:
     all modules verified

4. go mod graph
   - Visualizes the dependency graph.

5. go mod why <module>
   - Explains why a specific module is required.

6. go mod edit
   - Edits the go.mod file.
     Examples:
     - go mod edit -go <version>: Sets the Go version.
     - go mod edit -module <module_name>: Renames the module.

7. go mod vendor
   - Creates a vendor folder containing all dependencies locally.
     Usage:
     go run -mod=vendor .\main.go

   Note: Using vendor is generally not recommended in modern Go projects.

Dependency Files
- go.sum
  - Tracks the hash values of fetched module versions. If a module changes unexpectedly, the hash check fails and throws an error.

Java Comparison:
Similar to Java's Maven dependencies stored in C:/Users/<username>/.m2/, Go stores dependencies in:
C:/Users/<username>/go/pkg/mod/cache/download

Listing and Querying Modules
1. go list
   - Lists the current module.
2. go list all
   - Lists all installed packages.
3. go list -m all
   - Lists all module dependencies in the project.
4. go list -m -versions <module>
   - Lists available versions of a specific module.

Environment Variables
- go env
  - Displays environment variables, including GOMODCACHE, the location of the module cache.