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Published: Nov 23, 2021 License: Apache-2.0 Imports: 21 Imported by: 0



Package params provides a namespaced module parameter store.

There are two core components, Keeper and Subspace. Subspace is an isolated namespace for a parameter store, where keys are prefixed by pre-configured subspace names which modules provide. The Keeper has a permission to access all existing subspaces.

Subspace can be used by the individual keepers, who needs a private parameter store that the other keeper cannot modify. Keeper can be used by the Governance keeper, who need to modify any parameter in case of the proposal passes.

Basic Usage:

1. Declare constant module parameter keys and the globally unique Subspace name:

const (
	ModuleSubspace = "mymodule"

const (
	KeyParameter1 = "myparameter1"
	KeyParameter2 = "myparameter2"

2. Create a concrete parameter struct and define the validation functions:

type MyParams struct {
	MyParam1 int64 `json:"my_param1" yaml:"my_param1"`
	MyParam2 bool `json:"my_param2" yaml:"my_param2"`

func validateMyParam1(i interface{}) error {
	_, ok := i.(int64)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)

	// validate (if necessary)...

	return nil

func validateMyParam2(i interface{}) error {
	_, ok := i.(bool)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)

	// validate (if necessary)...

	return nil

3. Implement the params.ParamSet interface:

func (p *MyParams) ParamSetPairs() params.ParamSetPairs {
	return params.ParamSetPairs{
		{KeyParameter1, &p.MyParam1, validateMyParam1},
		{KeyParameter2, &p.MyParam2, validateMyParam2},

func paramKeyTable() params.KeyTable {
	return params.NewKeyTable().RegisterParamSet(&MyParams{})

4. Have the module accept a Subspace in the constructor and set the KeyTable (if necessary):

func NewKeeper(..., paramSpace params.Subspace, ...) Keeper {
	// set KeyTable if it has not already been set
	if !paramSpace.HasKeyTable() {
		paramSpace = paramSpace.WithKeyTable(paramKeyTable())

	return Keeper {
		// ...
		paramSpace: paramSpace,

Now we have access to the module's parameters that are namespaced using the keys defined:

func InitGenesis(ctx sdk.Context, k Keeper, gs GenesisState) {
	// ...
	k.SetParams(ctx, gs.Params)

func (k Keeper) SetParams(ctx sdk.Context, params Params) {
	k.paramSpace.SetParamSet(ctx, &params)

func (k Keeper) GetParams(ctx sdk.Context) (params Params) {
	k.paramSpace.GetParamSet(ctx, &params)
	return params

func (k Keeper) MyParam1(ctx sdk.Context) (res int64) {
	k.paramSpace.Get(ctx, KeyParameter1, &res)
	return res

func (k Keeper) MyParam2(ctx sdk.Context) (res bool) {
	k.paramSpace.Get(ctx, KeyParameter2, &res)
	return res

NOTE: Any call to SetParamSet will panic or any call to Update will error if any given parameter value is invalid based on the registered value validation function.



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func NewParamChangeProposalHandler

func NewParamChangeProposalHandler(k keeper.Keeper) govtypes.Handler

NewParamChangeProposalHandler creates a new governance Handler for a ParamChangeProposal


type AppModule

type AppModule struct {
	// contains filtered or unexported fields

AppModule implements an application module for the distribution module.

func NewAppModule

func NewAppModule(k keeper.Keeper) AppModule

NewAppModule creates a new AppModule object

func (AppModule) BeginBlock

func (AppModule) BeginBlock(_ sdk.Context, _ abci.RequestBeginBlock)

BeginBlock performs a no-op.

func (AppModule) EndBlock

EndBlock performs a no-op.

func (AppModule) ExportGenesis

func (am AppModule) ExportGenesis(_ sdk.Context, _ codec.JSONMarshaler) json.RawMessage

ExportGenesis performs a no-op.

func (AppModule) GenerateGenesisState

func (AppModule) GenerateGenesisState(simState *module.SimulationState)

GenerateGenesisState performs a no-op.

func (AppModule) InitGenesis

InitGenesis performs a no-op.

func (AppModule) LegacyQuerierHandler

func (am AppModule) LegacyQuerierHandler(legacyQuerierCdc *codec.LegacyAmino) sdk.Querier

LegacyQuerierHandler returns the x/params querier handler.

func (AppModule) ProposalContents

func (am AppModule) ProposalContents(simState module.SimulationState) []simtypes.WeightedProposalContent

ProposalContents returns all the params content functions used to simulate governance proposals.

func (AppModule) QuerierRoute

func (AppModule) QuerierRoute() string

QuerierRoute returns the x/param module's querier route name.

func (AppModule) RandomizedParams

func (AppModule) RandomizedParams(r *rand.Rand) []simtypes.ParamChange

RandomizedParams creates randomized distribution param changes for the simulator.

func (AppModule) RegisterInvariants

func (am AppModule) RegisterInvariants(_ sdk.InvariantRegistry)

func (AppModule) RegisterServices

func (am AppModule) RegisterServices(cfg module.Configurator)

RegisterServices registers a gRPC query service to respond to the module-specific gRPC queries.

func (AppModule) RegisterStoreDecoder

func (AppModule) RegisterStoreDecoder(sdr sdk.StoreDecoderRegistry)

RegisterStoreDecoder doesn't register any type.

func (AppModule) Route

func (AppModule) Route() sdk.Route

func (AppModule) WeightedOperations

func (am AppModule) WeightedOperations(_ module.SimulationState) []simtypes.WeightedOperation

WeightedOperations returns the all the gov module operations with their respective weights.

type AppModuleBasic

type AppModuleBasic struct{}

AppModuleBasic defines the basic application module used by the params module.

func (AppModuleBasic) DefaultGenesis

func (AppModuleBasic) DefaultGenesis(_ codec.JSONMarshaler) json.RawMessage

DefaultGenesis returns default genesis state as raw bytes for the params module.

func (AppModuleBasic) GetQueryCmd

func (AppModuleBasic) GetQueryCmd() *cobra.Command

GetQueryCmd returns no root query command for the params module.

func (AppModuleBasic) GetTxCmd

func (AppModuleBasic) GetTxCmd() *cobra.Command

GetTxCmd returns no root tx command for the params module.

func (AppModuleBasic) Name

func (AppModuleBasic) Name() string

Name returns the params module's name.

func (AppModuleBasic) RegisterGRPCGatewayRoutes

func (AppModuleBasic) RegisterGRPCGatewayRoutes(clientCtx client.Context, mux *runtime.ServeMux)

RegisterGRPCGatewayRoutes registers the gRPC Gateway routes for the params module.

func (AppModuleBasic) RegisterInterfaces

func (am AppModuleBasic) RegisterInterfaces(registry codectypes.InterfaceRegistry)

func (AppModuleBasic) RegisterLegacyAminoCodec

func (AppModuleBasic) RegisterLegacyAminoCodec(cdc *codec.LegacyAmino)

RegisterLegacyAminoCodec registers the params module's types on the given LegacyAmino codec.

func (AppModuleBasic) RegisterRESTRoutes

func (AppModuleBasic) RegisterRESTRoutes(_ client.Context, _ *mux.Router)

RegisterRESTRoutes registers the REST routes for the params module.

func (AppModuleBasic) ValidateGenesis

ValidateGenesis performs genesis state validation for the params module.


Path Synopsis
To prevent namespace collision between consumer modules, we define a type Subspace.
To prevent namespace collision between consumer modules, we define a type Subspace.
Package proposal is a reverse proxy.
Package proposal is a reverse proxy.

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