Init function
An init function is a special Go package-level function that runs automatically during package initialization before ordinary program execution.
100 Go Mistakes and How to Avoid Them
An init function is a special Go function that runs automatically to perform package initialization before program execution begins.
- How it is used
- Uses automatic package initialization for state setup and deliberate side effects, while cautioning against hiding application startup inside init.
- How deep it goes
- Explains signatures, package dependencies, file ordering, blank imports, and testing and error-handling trade-offs, but not runtime internals.
- Examples
- Demonstrates variable-init output, dependent redis and main packages, multiple init functions, blank imports, database setup, and HTTP handler registration.
- What you can do after
- Diagnose initialization-order and startup-design problems, then move failure-prone setup into caller-controlled functions.
Read how 100 Go Mistakes and How to Avoid Them explains init function →
Go by Example
An init function is a special Go function that runs automatically during package initialization before program execution begins.
- How it is used
- Registers database drivers automatically through blank imports during package initialization.
- How deep it goes
- Explains one-time implicit execution and demonstrates registry registration, while recommending explicit initialization for most other cases.
- Examples
- Demonstrates blank-importing modernc.org/sqlite and registering the driver in database/sql.
- What you can do after
- Operate SQLite driver registration by adding a blank import and understanding its automatic initialization.
Related concepts
- packagepart of · A package is a programming-language namespace and organizational unit that groups related code and may define import, compilation, or access boundaries.
- exceptioncontrasts with · An exception is a runtime signal or object representing an abnormal condition that interrupts ordinary program flow and may be handled or propagated.
- connection poolinguses · Connection pooling is a resource-management technique that maintains a collection of established connections for reuse across multiple operations.
- command-line argumentconfigures · A command-line argument is a value supplied to a program when it is invoked, either as positional input or as an option that configures its behavior.
- testcontrasts with · A test is a procedure or check that evaluates behavior using specified inputs or evidence against expected results or criteria.
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