プログラムで
identifier(識別子) の参照が検出されると、その
identifier(識別子) を導入した宣言を見つけるために
look-up(検索参照) が実行されます。
序文:
検索する識別子は、修飾されていない場合と修飾されている場合があります:
- 修飾されていない識別子は、それがどのスコープに由来するかを指定するためのプレフィックスを持たない識別子です。
- 修飾された識別子には、デフォルトのスコープを上書きすることによって解釈スコープを明確にするためのプレフィックスが含まれています。
非修飾識別子検索は、次のように優先順位階層を検証します:
- [1] Current Namespace/Type.
- [2] Base Types (by Extends), ranked from closest to furthest in inheritance hierarchy.
- [3] Parent Namespaces (by nesting), ranked from closest to furthest in ancestry hierarchy (including global namespace: always furthest in hierarchy).
- [4] Imported Namespaces (by Using), without hierarchy between them (regardless of their respective level of nesting).
Unqualified identifiers for look-up can be:
- Variable identifiers.
=> Look-up order: [1], [2], [3], [4].
- Procedure identifiers.
=> Look-up order: [1], [2], [3], [4].
- Type/Union identifiers.
=> Look-up order: [1], [3], [4].
- Enum identifiers, not their field symbols alone.
=> Look-up order: [1], [3], [4].
名前空間を参照するプレフィックスを持つ修飾識別子が、非修飾識別子の代わりに使用される場合、非修飾識別子の以前のルールは次のように修正されます:
- The look-up begins at the level of the namespace corresponding to the specified prefix (as in [1]).
- Failing that, then only namespaces imported into this namespace can be candidates for the look-up (as in [4]).
- But never the parent namespaces of this namespace nor also the global namespace can be candidates (not as in [3]).
=> Look-up order: [1], [4].
型を参照するプレフィックス（
object-name/This か
Base (member access)）を持つ修飾識別子が、非修飾識別子の代わりに使用される場合、非修飾識別子の以前のルールは次のように修正されます:
- The look-up begins at the level of the type or base type depending on the specified prefix object-name/This or Base (member access) (similarly to [1]).
- Failing that, then only higher base types from closest to furthest can be successively candidates for the look-up (as in [2]).
- But never any namespaces, the current also excluded, can be candidates (not as in [3] or [4]).
=> Look-up order: [1], [2].
完全プロセス
完全なプロセスは、2つの連続したフェーズで問題を処理することにより、問題を単純化します:
- Using the scope priority hierarchy rules above, selection of a single scope among all those which are accessible by only taking into account the identifier for look-up, regardless of the signature supplied by the caller (if at least two scopes containing this identifier have equivalent accessibility priority, then the process is stopped with an ambiguity status).
- Within the single scope retained if it exists, one final overload resolution taking into account the full signature is carried out (if there is no compatibility with the declared signature(s), the process is stopped without testing another accessible scope).
The problem is thus simplified to one single full overload resolution within a same scope (instead of a full overload resolution within each scope candidate, and then the difficult choice of the best result among the scope candidates).
The coding of a very optimized resolution process (the best of human intelligence) for a procedure identifier is cumbersome, because having to take into account from the start the complete signature of the called procedure (identifier of the procedure + type and number of parameters + calling convention + return type if it exists).
In addition, it must be taken into account that the signature deduced from the call may not necessarily be identical but just compatible with certain declared ones in the scope candidates.
Identifier look-ups for the overload non-member operators
Currently, the look-up for the overload non-member operator identifiers is simplified by the fact that the compiler always define these operators in the global namespace even if the user declared them in named namespaces.
But the global namespace is always a scope candidate when looking-up for a non-member overload operator identifier from another scope, because this operator identifier cannot be used with a qualifier prefix but always as an unqualified identifier (seen from the operator call, the global namespace is either the current namescape or a parent namescape).
Identifier look-ups for the Using commands
The look-up for the Using command identifiers follows rules similar to those of a Type.
例
次の 4つのコードは、さまざまなスコープのケース（最高から最低の優先順位の階層）で定義された手続きの 1つの非修飾識別子と 1つの修飾識別子の両方について異なる検索参照をテストします:
Sub duplicateSub()
Print " ..duplicateSub"
End Sub
Namespace M
Sub duplicateSub()
Print " M.duplicateSub"
End Sub
End Namespace
Namespace N
Sub duplicateSub()
Print " N.duplicateSub"
End Sub
Namespace P
Using M
Sub duplicateSub()
Print " N.P.duplicateSub"
End Sub
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
duplicateSub()
End Sub
End Namespace
End Namespace
Print "From Namespace:"
' "N.P.test()" calls the unqualified identifier "duplicateSub"
' "N.P.duplicateSub()" calls the qualified identifier "N.P.duplicateSub"
N.P.test() '' "N.P.duplicateSub" expected : in (1) current namespace/type
N.P.duplicateSub() '' "N.P.duplicateSub" expected : in (1) current namespace/type
Print
Sleep
Sub duplicateSub()
Print " ..duplicateSub"
End Sub
Namespace M
Sub duplicateSub()
Print " M.duplicateSub"
End Sub
End Namespace
Namespace N
Sub duplicateSub()
Print " N.duplicateSub"
End Sub
Namespace P
Using M
'Sub duplicateSub()
' Print " N.P.duplicateSub"
'End Sub
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
duplicateSub()
End Sub
End Namespace
End Namespace
Print "From Namespace:"
' "N.P.test()" calls the unqualified identifier "duplicateSub"
' "N.P.duplicateSub()" calls the qualified identifier "N.P.duplicateSub"
N.P.test() '' "N.duplicateSub" expected : in [3] parent namespaces (by nesting)
N.P.duplicateSub() '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
Sub duplicateSub()
Print " ..duplicateSub"
End Sub
Namespace M
Sub duplicateSub()
Print " M.duplicateSub"
End Sub
End Namespace
Namespace N
'Sub duplicateSub()
' Print " N.duplicateSub"
'End Sub
Namespace P
Using M
'Sub duplicateSub()
' Print " N.P.duplicateSub"
'End Sub
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
duplicateSub()
End Sub
End Namespace
End Namespace
Print "From Namespace:"
' "N.P.test()" calls the unqualified identifier "duplicateSub"
' "N.P.duplicateSub()" calls the qualified identifier "N.P.duplicateSub"
N.P.test() '' "..duplicateSub" expected : in [3] parent namespaces (by nesting)
N.P.duplicateSub() '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
'Sub duplicateSub()
' Print " ..duplicateSub"
'End Sub
Namespace M
Sub duplicateSub()
Print " M.duplicateSub"
End Sub
End Namespace
Namespace N
'Sub duplicateSub()
' Print " N.duplicateSub"
'End Sub
Namespace P
Using M
'Sub duplicateSub()
' Print " N.P.duplicateSub"
'End Sub
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
duplicateSub()
End Sub
End Namespace
End Namespace
Print "From Namespace:"
' "N.P.test()" calls the unqualified identifier "duplicateSub"
' "N.P.duplicateSub()" calls the qualified identifier "N.P.duplicateSub"
N.P.test() '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
N.P.duplicateSub() '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
次の 6つのコードは、さまざまなスコープケース（最高から最低の優先順位階層）で定義された変数の 1つの非修飾識別子と 1つの修飾識別子の両方について異なる検索参照をテストします:
Dim Shared As ZString * 32 duplicateVar = " ..duplicateVar"
Namespace M
Dim As ZString *32 duplicateVar = " M.duplicateVar"
End Namespace
Namespace N
Using M
Dim As ZString * 32 duplicateVar = " N.duplicateVar"
Type Parent Extends Object
Dim As ZString * 32 duplicateVar = " N.Parent.duplicateVar"
End Type
Type Child Extends Parent
Dim As ZString * 32 duplicateVar = " N.Child.duplicateVar"
End Type
Type GrandChild Extends Child
Dim As ZString * 32 duplicateVar = " N.GrandChild.duplicateVar"
Declare Sub test()
End Type
Sub GrandChild.test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print duplicateVar
End Sub
End Namespace
Print "From Type:"
Dim As N.GrandChild gc
' "gc.test()" calls the unqualified identifier "duplicateVar"
' "Print gc.duplicateVar" calls the qualified identifier "gc.duplicateVar"
gc.test() '' "N.GrandChild.duplicateVar" expected : in [1] current namespace/type
Print gc.duplicateVar '' "N.GrandChild.duplicateVar" expected : in [1] current namespace/type
Print
Sleep
Dim Shared As ZString * 32 duplicateVar = " ..duplicateVar"
Namespace M
Dim As ZString *32 duplicateVar = " M.duplicateVar"
End Namespace
Namespace N
Using M
Dim As ZString * 32 duplicateVar = " N.duplicateVar"
Type Parent Extends Object
Dim As ZString * 32 duplicateVar = " N.Parent.duplicateVar"
End Type
Type Child Extends Parent
Dim As ZString * 32 duplicateVar = " N.Child.duplicateVar"
End Type
Type GrandChild Extends Child
'Dim As Zstring * 32 duplicateVar = " N.GrandChild.duplicateVar"
Declare Sub test()
End Type
Sub GrandChild.test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print duplicateVar
End Sub
End Namespace
Print "From Type:"
Dim As N.GrandChild gc
' "gc.test()" calls the unqualified identifier "duplicateVar"
' "Print gc.duplicateVar" calls the qualified identifier "gc.duplicateVar"
gc.test() '' "N.Child.duplicateVar" expected : in [2] base types (by 'Extends')
Print gc.duplicateVar '' "N.Child.duplicateVar" expected : in [2] base types (by 'Extends')
Print
Sleep
Dim Shared As ZString * 32 duplicateVar = " ..duplicateVar"
Namespace M
Dim As ZString *32 duplicateVar = " M.duplicateVar"
End Namespace
Namespace N
Using M
Dim As ZString * 32 duplicateVar = " N.duplicateVar"
Type Parent Extends Object
Dim As ZString * 32 duplicateVar = " N.Parent.duplicateVar"
End Type
Type Child Extends Parent
'Dim As Zstring * 32 duplicateVar = " N.Child.duplicateVar"
End Type
Type GrandChild Extends Child
'Dim As Zstring * 32 duplicateVar = " N.GrandChild.duplicateVar"
Declare Sub test()
End Type
Sub GrandChild.test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print duplicateVar
End Sub
End Namespace
Print "From Type:"
Dim As N.GrandChild gc
' "gc.test()" calls the unqualified identifier "duplicateVar"
' "Print gc.duplicateVar" calls the qualified identifier "gc.duplicateVar"
gc.test() '' "N.Parent.duplicateVar" expected : in [2] base types (by 'Extends')
Print gc.duplicateVar '' "N.Parent.duplicateVar" expected : in [2] base types (by 'Extends')
Print
Sleep
Dim Shared As ZString * 32 duplicateVar = " ..duplicateVar"
Namespace M
Dim As ZString *32 duplicateVar = " M.duplicateVar"
End Namespace
Namespace N
Using M
Dim As ZString * 32 duplicateVar = " N.duplicateVar"
Type Parent Extends Object
'Dim As Zstring * 32 duplicateVar = " N.Parent.duplicateVar"
End Type
Type Child Extends Parent
'Dim As Zstring * 32 duplicateVar = " N.Child.duplicateVar"
End Type
Type GrandChild Extends Child
'Dim As Zstring * 32 duplicateVar = " N.GrandChild.duplicateVar"
Declare Sub test()
End Type
Sub GrandChild.test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print duplicateVar
End Sub
End Namespace
Print "From Type:"
Dim As N.GrandChild gc
' "gc.test()" calls the unqualified identifier "duplicateVar"
' "Print gc.duplicateVar" calls the qualified identifier "gc.duplicateVar"
gc.test() '' "N.duplicateVar" expected : in [3] parent namespaces (by nesting)
'Print gc.duplicateVar '' error
Print
Sleep
Dim Shared As ZString * 32 duplicateVar = " ..duplicateVar"
Namespace M
Dim As ZString *32 duplicateVar = " M.duplicateVar"
End Namespace
Namespace N
Using M
'Dim As Zstring * 32 duplicateVar = " N.duplicateVar"
Type Parent Extends Object
'Dim As Zstring * 32 duplicateVar = " N.Parent.duplicateVar"
End Type
Type Child Extends Parent
'Dim As Zstring * 32 duplicateVar = " N.Child.duplicateVar"
End Type
Type GrandChild Extends Child
'Dim As Zstring * 32 duplicateVar = " N.GrandChild.duplicateVar"
Declare Sub test()
End Type
Sub GrandChild.test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print duplicateVar
End Sub
End Namespace
Print "From Type:"
Dim As N.GrandChild gc
' "gc.test()" calls the unqualified identifier "duplicateVar"
' "Print gc.duplicateVar" calls the qualified identifier "gc.duplicateVar"
gc.test() '' "..duplicateVar" expected : in [3] parent namespaces (by nesting)
'Print gc.duplicateVar '' error
Print
Sleep
'Dim Shared As Zstring * 32 duplicateVar = " ..duplicateVar"
Namespace M
Dim As ZString *32 duplicateVar = " M.duplicateVar"
End Namespace
Namespace N
Using M
'Dim As Zstring * 32 duplicateVar = " N.duplicateVar"
Type Parent Extends Object
'Dim As Zstring * 32 duplicateVar = " N.Parent.duplicateVar"
End Type
Type Child Extends Parent
'Dim As Zstring * 32 duplicateVar = " N.Child.duplicateVar"
End Type
Type GrandChild Extends Child
'Dim As Zstring * 32 duplicateVar = " N.GrandChild.duplicateVar"
Declare Sub test()
End Type
Sub GrandChild.test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print duplicateVar
End Sub
End Namespace
Print "From Type:"
Dim As N.GrandChild gc
' "gc.test()" calls the unqualified identifier "duplicateVar"
' "Print gc.duplicateVar" calls the qualified identifier "gc.duplicateVar"
gc.test() '' "M.duplicateVar" expected : in [4] imported namespaces (by 'Using')
'Print gc.duplicateVar '' error
Print
Sleep
次の 4つのコードは、さまざまなスコープケース（最高から最低の優先順位階層）で定義された型の 1つの非修飾識別子と 1つの修飾識別子の両方について異なる検索参照をテストします:
Type duplicateType
Dim As ZString * 32 root = " ..duplicateType"
End Type
Namespace M
Type duplicateType
Dim As ZString * 32 root = " M.duplicateType"
End Type
End Namespace
Namespace N
Type duplicateType
Dim As ZString * 32 root = " N.duplicateType"
End Type
Namespace P
Using M
Type duplicateType
Dim As ZString * 32 root = " N.P.duplicateType"
End Type
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print Type<duplicateType>.root
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateType"
' "Print Type<N.P.duplicateType>.root" calls the qualified identifier "N.P.duplicateType"
Print "From Namespace:"
N.P.test() '' "N.P.duplicateSub" expected : in (1) current namespace/type
Print Type<N.P.duplicateType>.root '' "N.P.duplicateSub" expected : in (1) current namespace/type
Print
Sleep
Type duplicateType
Dim As ZString * 32 root = " ..duplicateType"
End Type
Namespace M
Type duplicateType
Dim As ZString * 32 root = " M.duplicateType"
End Type
End Namespace
Namespace N
Type duplicateType
Dim As ZString * 32 root = " N.duplicateType"
End Type
Namespace P
Using M
'Type duplicateType
' Dim As Zstring * 32 root = " N.P.duplicateType"
'End type
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print Type<duplicateType>.root
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateType"
' "Print Type<N.P.duplicateType>.root" calls the qualified identifier "N.P.duplicateType"
Print "From Namespace:"
N.P.test() '' "N.duplicateSub" expected : in [3] parent namespaces (by nesting)
Print Type<N.P.duplicateType>.root '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
Type duplicateType
Dim As ZString * 32 root = " ..duplicateType"
End Type
Namespace M
Type duplicateType
Dim As ZString * 32 root = " M.duplicateType"
End Type
End Namespace
Namespace N
'Type duplicateType
' Dim As Zstring * 32 root = " N.duplicateType"
'End type
Namespace P
Using M
'Type duplicateType
' Dim As Zstring * 32 root = " N.P.duplicateType"
'End type
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print Type<duplicateType>.root
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateType"
' "Print Type<N.P.duplicateType>.root" calls the qualified identifier "N.P.duplicateType"
Print "From Namespace:"
N.P.test() '' "..duplicateSub" expected : in [3] parent namespaces (by nesting)
Print Type<N.P.duplicateType>.root '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
'Type duplicateType
' Dim As Zstring * 32 root = " ..duplicateType"
'End type
Namespace M
Type duplicateType
Dim As ZString * 32 root = " M.duplicateType"
End Type
End Namespace
Namespace N
'Type duplicateType
' Dim As Zstring * 32 root = " N.duplicateType"
'End type
Namespace P
Using M
'Type duplicateType
' Dim As Zstring * 32 root = " N.P.duplicateType"
'End type
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print Type<duplicateType>.root
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateType"
' "Print Type<N.P.duplicateType>.root" calls the qualified identifier "N.P.duplicateType"
Print "From Namespace:"
N.P.test() '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print Type<N.P.duplicateType>.root '' "M.duplicateSub" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
次の4つのコードは、さまざまなスコープケース（優先度の高い階層から低い階層まで）で定義された列挙型の 1つの非修飾識別子と 1つの修飾識別子の両方について異なる検索参照をテストします:
Dim Shared As ZString * 32 root(...) = {" ..duplicateEnum", " M.duplicateEnum", " N.duplicateEnum", " N.P.duplicateEnum"}
Enum duplicateEnum
nb = 0
End Enum
Namespace M
Enum duplicateEnum
nb = 1
End Enum
End Namespace
Namespace N
Enum duplicateEnum
nb = 2
End Enum
Namespace P
Using M
Enum duplicateEnum
nb = 3
End Enum
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print root(duplicateEnum.nb)
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateEnum"
' "Print root(N.P.duplicateEnum.nb)" calls the qualified identifier "N.P.duplicateEnum"
Print "From Namespace:"
N.P.test() '' "N.P.duplicateEnum" expected : in (1) current namespace/type
Print root(N.P.duplicateEnum.nb) '' "N.P.duplicateEnum" expected : in (1) current namespace/type
Print
Sleep
Dim Shared As ZString * 32 root(...) = {" ..duplicateEnum", " M.duplicateEnum", " N.duplicateEnum", " N.P.duplicateEnum"}
Enum duplicateEnum
nb = 0
End Enum
Namespace M
Enum duplicateEnum
nb = 1
End Enum
End Namespace
Namespace N
Enum duplicateEnum
nb = 2
End Enum
Namespace P
Using M
'Enum duplicateEnum
' nb = 3
'End Enum
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print root(duplicateEnum.nb)
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateEnum"
' "Print root(N.P.duplicateEnum.nb)" calls the qualified identifier "N.P.duplicateEnum"
Print "From Namespace:"
N.P.test() '' "N.duplicateEnum" expected : in [3] parent namespaces (by nesting)
Print root(N.P.duplicateEnum.nb) '' "M.duplicateEnum" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
Dim Shared As ZString * 32 root(...) = {" ..duplicateEnum", " M.duplicateEnum", " N.duplicateEnum", " N.P.duplicateEnum"}
Enum duplicateEnum
nb = 0
End Enum
Namespace M
Enum duplicateEnum
nb = 1
End Enum
End Namespace
Namespace N
'Enum duplicateEnum
' nb = 2
'End Enum
Namespace P
Using M
'Enum duplicateEnum
' nb = 3
'End Enum
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print root(duplicateEnum.nb)
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateEnum"
' "Print root(N.P.duplicateEnum.nb)" calls the qualified identifier "N.P.duplicateEnum"
Print "From Namespace:"
N.P.test() '' "..duplicateEnum" expected : in [3] parent namespaces (by nesting)
Print root(N.P.duplicateEnum.nb) '' "M.duplicateEnum" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
Dim Shared As ZString * 32 root(...) = {" ..duplicateEnum", " M.duplicateEnum", " N.duplicateEnum", " N.P.duplicateEnum"}
'Enum duplicateEnum
' nb = 0
'End Enum
Namespace M
Enum duplicateEnum
nb = 1
End Enum
End Namespace
Namespace N
'Enum duplicateEnum
' nb = 2
'End Enum
Namespace P
Using M
'Enum duplicateEnum
' nb = 3
'End Enum
Sub test()
Using M '' useless, but just to demonstrate that does not increase priority level of imported namespace
Print root(duplicateEnum.nb)
End Sub
End Namespace
End Namespace
' "N.P.test()" calls the unqualified identifier "duplicateEnum"
' "Print root(N.P.duplicateEnum.nb)" calls the qualified identifier "N.P.duplicateEnum"
Print "From Namespace:"
N.P.test() '' "M.duplicateEnum" expected : in [4] imported namespaces (by 'Using')
Print root(N.P.duplicateEnum.nb) '' "M.duplicateEnum" expected : in [4] imported namespaces (by 'Using')
Print
Sleep
- fbc 1.09.0. 〜
- fbc 1.09.0 より前, 優先順位の階層は、一貫性がなく、管理は不十分でした。
参照
