github.com/fibonacci-chain/fbc@v0.0.0-20231124064014-c7636198c1e9/libs/cosmos-sdk/docs/building-modules/structure.md (about)

     1  <!--
     2  order: 12
     3  synopsis: This document outlines the recommended structure of Cosmos SDK modules. These ideas are meant to be applied as suggestions. Application developers are encouraged to improve upon and contribute to module structure and development design.
     4  -->
     5  
     6  # Recommended Folder Structure
     7  
     8  ## Structure
     9  
    10  A typical Cosmos SDK module can be structured as follows:
    11  
    12  ```shell
    13  x/{module}
    14  ├── client
    15  │   ├── cli
    16  │   │   ├── query.go
    17  │   │   └── tx.go
    18  │   └── rest
    19  │       ├── query.go
    20  │       └── tx.go
    21  ├── exported
    22  │   └── exported.go
    23  ├── internal
    24  │   ├── keeper
    25  │   │   ├── invariants.go
    26  │   │   ├── keeper.go
    27  │   │   ├── ...
    28  │   │   └── querier.go
    29  │   └── types
    30  │       ├── codec.go
    31  │       ├── errors.go
    32  │       ├── events.go
    33  │       ├── expected_keepers.go
    34  │       ├── genesis.go
    35  │       ├── keys.go
    36  │       ├── msgs.go
    37  │       ├── params.go
    38  │       ├── ...
    39  │       └── querier.go
    40  ├── abci.go
    41  ├── alias.go
    42  ├── genesis.go
    43  ├── handler.go
    44  ├── module.go
    45  ├── ...
    46  └── simulation.go
    47  ```
    48  
    49  - `abci.go`: The module's `BeginBlocker` and `EndBlocker` implementations (if any).
    50  - `alias.go`: The module's exported types, constants, and variables. These are mainly
    51  to improve developer ergonomics by only needing to import a single package. Note,
    52  there is nothing preventing developers from importing other packages from the module
    53  (excluding`internal/`) but it is recommended that `alias.go` have everything
    54  exposed that other modules may need. The majority of the exported values here will
    55  typically come from `internal/` (see below).
    56  - `client/`: The module's CLI and REST client functionality implementation and 
    57  testing.
    58  - `exported/`: The module's exported types -- typically type interfaces. If a module
    59  relies on other module keepers, it is expected to receive them as interface
    60  contracts through the `expected_keepers.go` (which are detailed below) design to
    61  avoid having a direct dependency on the implementing module. However, these
    62  contracts can define methods that operate on and/or return types that are specific
    63  to the contract's implementing module and this is where `exported/` comes into play.
    64  Types defined here allow for `expected_keepers.go` in other modules to define
    65  contracts that use single canonical types. This pattern allows for code to remain
    66  DRY and also alleviates import cycle chaos.
    67  - `genesis.go`: The module's genesis related business logic (e.g. `InitGenesis`).
    68  Note, genesis types are defined in `internal/types`.
    69  - `handler.go`: The module's message handlers.
    70  - `internal/`: The module's internal types and implementations. The purpose of
    71  this package is mainly two fold. First, it signals that this package is not
    72  intended to be used or imported anywhere outside the defining module. Secondly,
    73  it goes hand-in-hand with `alias.go` in that it allows public types and functions
    74  to be used internally while not being exposed outside to the outside world. This
    75  allows for greater freedom of development while maintaining API stability.
    76    - `internal/types`: The module's type definitions such as messages, `KVStore`
    77    keys, parameter types, and `expected_keepers.go` contracts.
    78    - `internal/keeper`: The module's keeper implementation along with any auxiliary
    79    implementations such as the querier and invariants.
    80  - `module.go`: The module's implementation of the `AppModule` and `AppModuleBasic`
    81  interfaces.
    82  - `simulation.go`: The module's simulation messages and related types (if any).
    83  
    84  ## Next {hide}
    85  
    86  Learn about [interfaces](../interfaces/interfaces-intro.md) {hide}