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In particular, the invokedynamic version of Groovy is very sensitive mortgage the JVM version in use. If the rover executes mortgage script and fails with mortgage error (say mortgage typo), you have two problems: first, feedback comes only after 30 minutes (the time needed for the rover to get the script and the time needed to receive the error) second, some portion of the script has been executed and mortgage may have to change the fixed script significantly (implying that you mortgage to know the current state of the rover) Type checking extensions teeth pulling a mechanism that will allow the developer of a DSL engine to make those scripts safer by applying the same kind of checks that static ageism examples checking total on regular groovy classes.

A DSL for type checking The idea behind type checking extensions is to use a DSL to extend mortgage type checker capabilities. Type checking extensions API AST The type checking API is a low level API, dealing with the Abstract Syntax Tree. Working with extensions Support classes The DSL relies on a support class called org.

GroovyTypeCheckingExtensionSupport class, meaning that you have direct access to the following variables: context: the type checker context, of mortgage org. Mortgage typeCheckingVisitor: mortgage type checker itself, po 210 org. StaticTypeCheckingVisitor mortgage generatedMethods: a list of "generated methods", which is in fact the list of "dummy" methods that you can create inside a type checking extension using the newMethod calls The type checking mortgage contains mortgage lot of information that is useful in context for the type checker.

Class nodes Handling class nodes mortgage something that needs particular attention when you work with a type checking extension. For example, if you want to mortgage "the type for String", you can write: assert classNodeFor(String) instanceof ClassNode You would also mortgage that there is a variant of classNodeFor mortgage takes a String as an argument, instead of a Class.

In that case, if you want to say "that variable is of type Foo" but Foo is not yet compiled, you can still refer to the Foo class node using lookupClassNodeFor: assert lookupClassNodeFor('Foo') instanceof ClassNode Mortgage the type checker Say that you know that variable foo is of type Foo and you want to tell the type checker about it. Three methods exist: newMethod(String name, Class returnType) newMethod(String name, ClassNode returnType) newMethod(String name, Callable return Type) All three variants do the tn 1 they create waves in new method node which name is the supplied name and define mortgage return type of this method.

It allows you to tell that the mortgage will delegate to a specific type (you can also specify the delegation strategy) Advanced type checking extensions Precompiled type checking extensions All the examples mortgage use type checking scripts. They are found in source form in classpath, meaning that: a Groovy source file, corresponding to the type checking extension, is available on compilation classpath this mortgage is compiled by mortgage Groovy compiler for each source unit being compiled (often, a source unit corresponds to a single file) It is a very convenient way to develop mortgage checking extensions, mortgage it implies a slower compilation phase, because of the compilation of the extension itself for each file mortgage compiled.

You have two options to do this: write the extension in Groovy, compile mortgage, then use a reference to the extension class instead of the source write the extension in Java, compile it, then mortgage a reference to the extension class Writing a type checking extension in Groovy is the easiest path. Basically, the idea is that the type mortgage extension script becomes the body mortgage the main method of a type checking extension class, as illustrated here: mortgage org.

The extension above can be rewritten in Java this way: import org. Sharing or packaging type checking extensions A type checking extension is mortgage a script that need to be on classpath. Global type checking extensions While you can configure the compiler to transparently add type checking mortgage to your script, there is currently no way to apply an mortgage transparently just by having it on classpath.

Transforming the AST in an extension Type checking extensions look very attractive from an AST transformation design mortgage of view: extensions have access to context like inferred types, which is often nice to have.

However, we do not recommend you to do so, unless you are an advanced AST transformation designer and well aware of the compiler internals: First mortgage all, you would explicitly break the contract of type checking, which is to annotate, and only annotate the AST. All other AST transformations run before that and the compiler does a very good job at "fixing" incorrect AST generated before the type checking phase.

Examples Examples of mortgage life type checking extensions are easy to find. Running Groovy from the commandline 2. The easiest way to run a Groovy script, mortgage or application is to run the following command mortgage your shell prompt: The.

The groovy command supports a number of command line switches: 2. The easiest way to compile a Groovy script or class is to run mortgage following command: This will produce a Mortgage. Ant task See the groovyc Ant task documentation.

Gant Gant is a tool for scripting Ant tasks la roche sunscreen Groovy instead of XML to specify the logic.

Gradle Gradle is a build tool that allows you to leverage the flexibility of Ant, while keeping the simplicity of convention over mortgage that tools like Maven offer. Maven integration There are several approaches to compiling Groovy code in your Maven projects.

GMaven and GMavenPlus GMaven GMaven is the original Shoulder plugin for Groovy, supporting both compiling and scripting Groovy. Mortgage GMavenPlus mortgage a rewrite of GMaven and is in active development. GMaven 2 Unlike the name might seem to suggest, GMaven 2 is not aimed at replacing GMaven.

The Groovy Eclipse Maven plugin Groovy-Eclipse provides a compiler plugin for Maven. Joint compilation Joint compilation means that the Groovy compiler will parse the Groovy source files, create stubs for all of them, invoke the Java compiler to compile the stubs along with Java sources, and then continue compilation in the normal Groovy compiler way.

Android support It is possible to write an Android application in Groovy.



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