BoundedVec + Shims for Append/DecodeLength

frame/example/src/lib.rs

@@ -26,8 +26,8 @@
 //!
 //! ### Documentation Guidelines:
 //!
-//! <!-- Original author of paragraph: Various. Based on collation of review comments to PRs addressing issues with -->
-//! <!-- label 'S3-FRAME' in https://github.com/paritytech/substrate-developer-hub/issues -->
+//! <!-- Original author of paragraph: Various. Based on collation of review comments to PRs
+//! addressing issues with --> <!-- label 'S3-FRAME' in https://github.com/paritytech/substrate-developer-hub/issues -->
 //! <ul>
 //!     <li>Documentation comments (i.e. <code>/// comment</code>) - should
 //!         accompany pallet functions and be restricted to the pallet interface,
@@ -37,13 +37,13 @@
 //!         Capitalize the first word of each documentation comment and end it with
 //!         a full stop. See
 //!         <a href="https://github.com/paritytech/substrate#72-contributing-to-documentation-for-substrate-packages"
-//!         target="_blank"> Generic example of annotating source code with documentation comments</a></li>
-//!     <li>Self-documenting code - Try to refactor code to be self-documenting.</li>
-//!     <li>Code comments - Supplement complex code with a brief explanation, not every line of code.</li>
-//!     <li>Identifiers - surround by backticks (i.e. <code>INHERENT_IDENTIFIER</code>, <code>InherentType</code>,
-//!         <code>u64</code>)</li>
-//!     <li>Usage scenarios - should be simple doctests. The compiler should ensure they stay valid.</li>
-//!     <li>Extended tutorials - should be moved to external files and refer to.</li>
+//!         target="_blank"> Generic example of annotating source code with documentation
+//! comments</a></li>     <li>Self-documenting code - Try to refactor code to be
+//! self-documenting.</li>     <li>Code comments - Supplement complex code with a brief explanation,
+//! not every line of code.</li>     <li>Identifiers - surround by backticks (i.e.
+//! <code>INHERENT_IDENTIFIER</code>, <code>InherentType</code>,         <code>u64</code>)</li>
+//!     <li>Usage scenarios - should be simple doctests. The compiler should ensure they stay
+//! valid.</li>     <li>Extended tutorials - should be moved to external files and refer to.</li>
 //!     <!-- Original author of paragraph: @AmarRSingh -->
 //!     <li>Mandatory - include all of the sections/subsections where <b>MUST</b> is specified.</li>
 //!     <li>Optional - optionally include sections/subsections where <b>CAN</b> is specified.</li>
@@ -84,12 +84,13 @@
 //!
 //! \## Terminology
 //!
-//! // Add terminology used in the custom pallet. Include concepts, storage items, or actions that you think
-//! // deserve to be noted to give context to the rest of the documentation or pallet usage. The author needs to
-//! // use some judgment about what is included. We don't want a list of every storage item nor types - the user
-//! // can go to the code for that. For example, "transfer fee" is obvious and should not be included, but
-//! // "free balance" and "reserved balance" should be noted to give context to the pallet.
-//! // Please do not link to outside resources. The reference docs should be the ultimate source of truth.
+//! // Add terminology used in the custom pallet. Include concepts, storage items, or actions that
+//! you think // deserve to be noted to give context to the rest of the documentation or pallet
+//! usage. The author needs to // use some judgment about what is included. We don't want a list of
+//! every storage item nor types - the user // can go to the code for that. For example, "transfer
+//! fee" is obvious and should not be included, but // "free balance" and "reserved balance" should
+//! be noted to give context to the pallet. // Please do not link to outside resources. The
+//! reference docs should be the ultimate source of truth.
 //!
 //! <!-- Original author of heading: @Kianenigma in PR https://github.com/paritytech/substrate/pull/1951 -->
 //!
@@ -106,7 +107,8 @@
 //! \#### <INSERT_SCENARIO_NAME>
 //!
 //! // Describe requirements prior to interacting with the custom pallet.
-//! // Describe the process of interacting with the custom pallet for this scenario and public API functions used.
+//! // Describe the process of interacting with the custom pallet for this scenario and public API
+//! functions used.
 //!
 //! \## Interface
 //!
@@ -130,14 +132,15 @@
 //!
 //! <!-- Original author of paragraph: ??? -->
 //!
-//! // Reference documentation of aspects such as `storageItems` and `dispatchable` functions should only be
-//! // included in the <https://docs.rs> Rustdocs for Substrate and not repeated in the README file.
+//! // Reference documentation of aspects such as `storageItems` and `dispatchable` functions should
+//! only be // included in the <https://docs.rs> Rustdocs for Substrate and not repeated in the README file.
 //!
 //! \### Dispatchable Functions
 //!
 //! <!-- Original author of paragraph: @AmarRSingh & @joepetrowski -->
 //!
-//! // A brief description of dispatchable functions and a link to the rustdoc with their actual documentation.
+//! // A brief description of dispatchable functions and a link to the rustdoc with their actual
+//! documentation.
 //!
 //! // <b>MUST</b> have link to Call enum
 //! // <b>MUST</b> have origin information included in function doc
@@ -154,7 +157,8 @@
 //!
 //! <!-- Original author of paragraph: @AmarRSingh -->
 //!
-//! // It is up to the writer of the respective pallet (with respect to how much information to provide).
+//! // It is up to the writer of the respective pallet (with respect to how much information to
+//! provide).
 //!
 //! \#### Public Inspection functions - Immutable (getters)
 //!
@@ -217,7 +221,8 @@
 //!
 //! \### Simple Code Snippet
 //!
-//! // Show a simple example (e.g. how to query a public getter function of <INSERT_CUSTOM_PALLET_NAME>)
+//! // Show a simple example (e.g. how to query a public getter function of
+//! <INSERT_CUSTOM_PALLET_NAME>)
 //!
 //! \### Example from FRAME
 //!
@@ -598,6 +603,22 @@ pub mod pallet {
 	#[pallet::getter(fn foo)]
 	pub(super) type Foo<T: Config> = StorageValue<_, T::Balance, ValueQuery>;
 
+	frame_support::parameter_types! {
+		pub const Five: u32 = 5;
+	}
+
+	/// An example of how to create a bounded vector. This is a special 'newtype' that behaves
+	/// identical to a normal `Vec`, except the size can never exceed `Five`.
+	///
+	/// Similar to normal storage values that contain a vector, the length of the bounded vector can
+	///be queried efficiently with `decode_len`. Also, adding to the end of the vector can be done
+	///efficiently via `try_append`. See [`frame_support::TryAppendValue`] and
+	/// [`frame_support::TryAppendMap`].
+	#[pallet::storage]
+	#[pallet::getter(fn bounded)]
+	pub(super) type BoundedStuff<T: Config> =
+		StorageValue<_, frame_support::storage::BoundedVec<u32, Five>, ValueQuery>;
+
 	// The genesis config type.
 	#[pallet::genesis_config]
 	pub struct GenesisConfig<T: Config> {

frame/support/src/lib.rs

@@ -75,7 +75,7 @@ pub use self::hash::{
 };
 pub use self::storage::{
 	StorageValue, StorageMap, StorageDoubleMap, StoragePrefixedMap, IterableStorageMap,
-	IterableStorageDoubleMap, migration
+	IterableStorageDoubleMap, migration, BoundedVec,
 };
 pub use self::dispatch::{Parameter, Callable};
 pub use sp_runtime::{self, ConsensusEngineId, print, traits::Printable};