On Wed, Sep 27, 2023 at 01:25:38PM +0200, Victor Toso wrote:
> This patch handles QAPI struct types and generates the equivalent
> types in Go. The following patch adds extra logic when a member of the
> struct has a Type that can take JSON Null value (e.g: StrOrNull in
> QEMU)
>
> The highlights of this implementation are:
>
> 1. Generating an Go struct that requires a @base type, the @base type
> fields are copied over to the Go struct. The advantage of this
> approach is to not have embed structs in any of the QAPI types.
> Note that embedding a @base type is recursive, that is, if the
> @base type has a @base, all of those fields will be copied over.
>
> 2. About the Go struct's fields:
>
> i) They can be either by Value or Reference.
>
> ii) Every field that is marked as optional in the QAPI specification
> are translated to Reference fields in its Go structure. This
> design decision is the most straightforward way to check if a
> given field was set or not. Exception only for types that can
> take JSON Null value.
>
> iii) Mandatory fields are always by Value with the exception of QAPI
> arrays, which are handled by Reference (to a block of memory) by
> Go.
>
> iv) All the fields are named with Uppercase due Golang's export
> convention.
>
> v) In order to avoid any kind of issues when encoding or decoding,
> to or from JSON, we mark all fields with its @name and, when it is
> optional, member, with @omitempty
>
> Example:
>
> qapi:
> | { 'struct': 'BlockdevCreateOptionsFile',
> | 'data': { 'filename': 'str',
> | 'size': 'size',
> | '*preallocation': 'PreallocMode',
> | '*nocow': 'bool',
> | '*extent-size-hint': 'size'} }
>
> go:
> | type BlockdevCreateOptionsFile struct {
> | Filename string `json:"filename"`
> | Size uint64 `json:"size"`
> | Preallocation *PreallocMode `json:"preallocation,omitempty"`
> | Nocow *bool `json:"nocow,omitempty"`
> | ExtentSizeHint *uint64 `json:"extent-size-hint,omitempty"`
> | }
Note, 'omitempty' shouldn't be used on pointer fields, only scalar
fields. The pointer fields are always omitted when nil.
With regards,
Daniel
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