patch 9.0.1909: Vim9: problem calling class method from other class
Problem: Vim9: problem calling class method from other class
Solution: Fix this problem, fix readonly object access, update error
messages.
Calling a class method from another method without the class name prefix
doesn't work properly.
A readonly object variable is modifiable outside the class using a
nested object assignment.
Remove the unused E1338 error message.
Update error messages.
closes: #13116
Signed-off-by: Christian Brabandt <cb@256bit.org>
Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>
This commit is contained in:
Yegappan Lakshmanan
committed by
Christian Brabandt
Christian Brabandt
parent
d25021cf03
commit
00cd18222e
@ -1,4 +1,4 @@
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*vim9class.txt* For Vim version 9.0. Last change: 2023 Mar 22
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*vim9class.txt* For Vim version 9.0. Last change: 2023 Sep 18
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VIM REFERENCE MANUAL by Bram Moolenaar
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@ -11,7 +11,7 @@ Vim9 classes, objects, interfaces, types and enums.
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1. Overview |Vim9-class-overview|
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2. A simple class |Vim9-simple-class|
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3. Class members and functions |Vim9-class-member|
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3. Class variables and methods |Vim9-class-member|
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4. Using an abstract class |Vim9-abstract-class|
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5. Using an interface |Vim9-using-interface|
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6. More class details |Vim9-class|
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@ -139,11 +139,13 @@ changed at any time, you can make it public: >
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Now you don't need the SetLnum(), SetCol() and SetPosition() methods, setting
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"pos.lnum" directly above will no longer give an error.
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*E1334*
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*E1326*
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If you try to set an object member that doesn't exist you get an error: >
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pos.other = 9
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< E1334: Object member not found: other ~
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< E1326: Member not found on object "TextPosition": other ~
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*E1376*
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A object member cannot be accessed using the class name.
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Private members ~
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*E1332* *E1333*
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@ -176,9 +178,9 @@ number to the total number of lines: >
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endif
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return this._lnum
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enddef
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<
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Private methods ~
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*E1366*
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If you want object methods to be accessible only from other methods of the
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same class and not used from outside the class, then you can make them
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private. This is done by prefixing the method name with an underscore: >
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@ -252,16 +254,17 @@ If the class extends a parent class, the same thing happens. In the second
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step the members of the parent class are done first. There is no need to call
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"super()" or "new()" on the parent.
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*E1365*
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When defining the new() method the return type should not be specified. It
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always returns an object of the class.
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==============================================================================
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3. class members and functions *Vim9-class-member*
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3. Class Variables and Methods *Vim9-class-member*
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*:static* *E1337* *E1338*
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*:static* *E1337* *E1338* *E1368*
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Class members are declared with "static". They are used by the name without a
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prefix: >
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prefix in the class where they are defined: >
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class OtherThing
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this.size: number
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@ -275,6 +278,10 @@ prefix: >
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Since the name is used as-is, shadowing the name by a function argument name
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or local variable name is not allowed.
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*E1374* *E1375*
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To access a class member outside of the class where it is defined, the class
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name prefix must be used. A class member cannot be accessed using an object.
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Just like object members the access can be made private by using an underscore
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as the first character in the name, and it can be made public by prefixing
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"public": >
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@ -285,10 +292,11 @@ as the first character in the name, and it can be made public by prefixing
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public static result: number # anybody can read and write
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endclass
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<
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*class-function*
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Class functions are also declared with "static". They have no access to
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object members, they cannot use the "this" keyword. >
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*class-method*
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Class methods are also declared with "static". They can use the class
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variables but they have no access to the object variables, they cannot use the
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"this" keyword.
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>
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class OtherThing
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this.size: number
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static totalSize: number
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@ -301,8 +309,9 @@ object members, they cannot use the "this" keyword. >
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enddef
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endclass
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Inside the class the function can be called by name directly, outside the
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class the class name must be prefixed: `OtherThing.ClearTotalSize()`.
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Inside the class the class method can be called by name directly, outside the
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class the class name must be prefixed: `OtherThing.ClearTotalSize()`. To use
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a super class method in a child class, the class name must be prefixed.
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Just like object methods the access can be made private by using an underscore
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as the first character in the method name: >
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@ -312,7 +321,7 @@ as the first character in the method name: >
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echo "Foo"
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enddef
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def Bar()
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OtherThing._Foo()
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_Foo()
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enddef
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endclass
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<
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@ -320,6 +329,31 @@ as the first character in the method name: >
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Note that constructors cannot be declared as "static", because they always
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are.
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To access the class methods and class variables of a super class in an
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extended class, the class name prefix should be used just as from anywhere
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outside of the defining class: >
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vim9script
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class Vehicle
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static nextID: number = 1000
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static def GetID(): number
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nextID += 1
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return nextID
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enddef
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endclass
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class Car extends Vehicle
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this.myID: number
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def new()
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this.myID = Vehicle.GetID()
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enddef
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endclass
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<
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Class variables and methods are not inherited by a child class. A child class
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can declare a static variable or a method with the same name as the one in the
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super class. Depending on the class where the member is used the
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corresponding class member will be used. The type of the class member in a
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child class can be different from that in the super class.
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==============================================================================
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4. Using an abstract class *Vim9-abstract-class*
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@ -358,16 +392,19 @@ class, for which objects can be created. Example: >
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An abstract class is defined the same way as a normal class, except that it
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does not have any new() method. *E1359*
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*abstract-method*
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*abstract-method* *E1371* *E1372*
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An abstract method can be defined in an abstract class by using the "abstract"
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prefix when defining the function: >
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abstract class Shape
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abstract def Draw()
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abstract static def SetColor()
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endclass
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<
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*E1373*
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A class extending the abstract class must implement all the abstract methods.
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Class methods in an abstract class can also be abstract methods.
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The signature (arguments, argument types and return type) must be exactly the
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same. Class methods in an abstract class can also be abstract methods.
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==============================================================================
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@ -409,9 +446,10 @@ a number. This example extends the one above: >
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return this.base * this.height / 2
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enddef
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endclass
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<
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*E1348* *E1349* *E1367* *E1382* *E1383*
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If a class declares to implement an interface, all the items specified in the
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interface must appear in the class, with the same types. *E1348* *E1349*
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interface must appear in the class, with the same types.
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The interface name can be used as a type: >
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@ -422,7 +460,14 @@ The interface name can be used as a type: >
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for shape in shapes
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echo $'the surface is {shape.Surface()}'
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endfor
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<
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*E1378* *E1379* *E1380*
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An interface can have only instance variables (read-only and read-write
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access) and methods. An interface cannot contain private variables, private
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methods, class variables and class methods.
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An interface can extend another interface using "extends". The sub-interface
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inherits all the instance variables and methods from the super interface.
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==============================================================================
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@ -464,9 +509,12 @@ once. They can appear in any order, although this order is recommended: >
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extends ClassName
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implements InterfaceName, OtherInterface
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specifies SomeInterface
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< *E1355*
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< *E1355* *E1369*
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Each member and function name can be used only once. It is not possible to
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define a function with the same name and different type of arguments.
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define a function with the same name and different type of arguments. It is
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not possible to use a public and private member variable with the same name.
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A object variable name used in a super class cannot be reused in a child
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class.
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Member Initialization ~
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@ -491,6 +539,10 @@ Object methods of the base class can be overruled. The signature (arguments,
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argument types and return type) must be exactly the same. The method of the
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base class can be called by prefixing "super.".
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*E1377*
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The access level of a method (public or private) in a child class should be
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the same as the super class.
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Other object methods of the base class are taken over by the child class.
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Class functions, including functions starting with "new", can be overruled,
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@ -523,18 +575,26 @@ interface, which is often done in many languages, especially Java.
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Items in a class ~
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*E1318* *E1325* *E1326*
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*E1318* *E1325*
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Inside a class, in between `:class` and `:endclass`, these items can appear:
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- An object member declaration: >
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this._memberName: memberType
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this.memberName: memberType
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public this.memberName: memberType
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this._privateMemberName: memberType
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this.readonlyMemberName: memberType
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public this.readwriteMemberName: memberType
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- A class member declaration: >
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static this._privateMemberName: memberType
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static this.readonlyMemberName: memberType
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static public this.readwriteMemberName: memberType
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- A constructor method: >
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def new(arguments)
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def newName(arguments)
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- A class method: >
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static def SomeMethod(arguments)
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static def _PrivateMethod(arguments)
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- An object method: >
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def SomeMethod(arguments)
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< *E1329*
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def _PrivateMethod(arguments)
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For the object member the type must be specified. The best way is to do this
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explicitly with ": {type}". For simple types you can also use an initializer,
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such as "= 123", and Vim will see that the type is a number. Avoid doing this
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@ -573,6 +633,8 @@ An interface name must start with an uppercase letter. *E1343*
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The "Has" prefix can be used to make it easier to guess this is an interface
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name, with a hint about what it provides.
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An interface can only be defined in a |Vim9| script file. *E1342*
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An interface cannot "implement" another interface but it can "extend" another
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interface. *E1381*
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null object ~
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