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Difference between revisions of "JDT Core/Plan/4.8/JEP286"
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== Content Assist support == | == Content Assist support == | ||
| − | * var to be included in completion - | + | * Top level bug at https://bugs.eclipse.org/bugs/show_bug.cgi?id=529556 |
| − | * Default camel case type to a little alphabet prefixed name will not work here - alternatives (low prio). | + | * var to be included in completion - https://bugs.eclipse.org/bugs/show_bug.cgi?id=529552 |
| + | * type. completions if the type is var - tracked via https://bugs.eclipse.org/bugs/show_bug.cgi?id=529556 | ||
| + | * name of the variable? Default camel case type to a little alphabet prefixed name will not work here - alternatives (low prio). | ||
* changes to priority of proposals ? | * changes to priority of proposals ? | ||
Revision as of 02:41, 9 January 2018
Contents
Planning page for JDT Implementation of Local Variable Type Inference (JEP 286) for Photon (4.8)
Main tracking bug: JEP286 Bug
Compiler changes
Changes regarding the compiler: Compiler Bug
Grammar changes
Since var is not a keyword, but a reserved type name AND we need to be backwards compatible anyway, it should be handled in type resolution instead of grammar. Local variable type inference should be denoted by a bit AST node and type binding.
Type checking
- Determine the type of the var declaration
- Determine upwards/downwards type projection for type
- Fallback to "Object" type in case of error
Error reports
- Errors where local variable type cannot be inferred:
- Cannot use 'var' on variable without initializer
- Lambda expression needs an explicit target-type
- Variable initializer is 'null'
- Inferred type is non denotable
- When method reference needs an explicit target-type.
- array initializer needs an explicit target-type
- Error when defining a type called 'var':
This should be a configurable 'warning'/'info' for Java 9 and earlier.
Code generation
Shouldn't be much work since the stack frame would be filled in with the bound type anyway.
Java Search support
Changes regarding the Search: Search Bug
DOM support
Changes regarding the DOM: DOM Bug
Content Assist support
- Top level bug at https://bugs.eclipse.org/bugs/show_bug.cgi?id=529556
- var to be included in completion - https://bugs.eclipse.org/bugs/show_bug.cgi?id=529552
- type. completions if the type is var - tracked via https://bugs.eclipse.org/bugs/show_bug.cgi?id=529556
- name of the variable? Default camel case type to a little alphabet prefixed name will not work here - alternatives (low prio).
- changes to priority of proposals ?
UI Changes
This hasn't been looked into yet. Some ideas:
Code hover
- Show inferred type of variable
Preferences
- 'Code Style' option to prefer 'var' over specific types (to control the irritants generated by the compiler)
Quick fixes
- Convert 'var' into the resolved type
- Convert explicit typed local variable into 'var', like changing "String coolIde = "Eclipse";" into "var coolIde = "Eclipse";"
- Convert diamond operator to var, like fixing "List<String> names = new LinkedList<>()" into "var names = new LinkedList<String>()"
Code templates
- Use 'var' in templates for loops and introduce new variable, if preferred by the code style.