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Use this page to list use cases for AST-level macros in Groovy.

How do you want to use such macros? Show examples of their usage (without showing how they're implemented). Add to the bottom of the page.

Increase code readability

Rearrange code portions

The end-weight principle for natural languages says the longer stuff should be at the end of a sentence.
In Groovy/Java, while and if statements are usually heavy in the block/statement, and light in the condition.
When the statement/block is short and the condition long, it can be more readable to put the block last.

Code Block
do{ i++; return c }if(
  ( severance.taxAmount >= TaxYear2006.taxAmounts.severanceLimit[ 'dependent' ] ||
     ... ... ...
     ... ... ...

is transformed to:

Code Block
if( ... ... ... ){ i++; return c }

We could use 'unless' and 'until' if using 'if' and 'while' caused problems.

Common modifier

When a long list of methods and/or fields have the same modifier/s,
it may be more readable to apply them to a whole block, eg:

Code Block
  def a(){ ... }
  def b(){ ... }


Code Block
static a(){ ... }
static b(){ ... }

Transform statements


Code Block
def genUniqueScriptName(){ static int i=1; 'Script_' + i++ }


Code Block
class UniqueScriptName{ static int i=1; static gen(){ 'Script_' + i++ }

triggered by the 'static' modifier of a field in a function.

Names for operators

Use names instead of symbols for operators, eg:

Code Block
if( a and b )


Code Block
if(a && b)

or change their names to something shorter, eg:

Code Block
if( a of A )


Code Block
if( a instanceof A )

Equivalence of block and statement 

Forgoing curlies for all statements, making a statement and block equivalent always:

Code Block
catch(e) if(e instanceof ABCException) throw new BusinessException()

Use other natural languages with Groovy

Enable fuller internationalization of Groovy, eg:

Code Block
mientras( i < 10 ){ ... ... ... }

would convert to 

Code Block
while( i < 10 ){ ... ... ... }

if a Spanish option for Groovy was loaded. 

More Seamless Integration with Java and Java-like languages

Embed Java code within Groovy without quoting it,
and without needing to bind variables to the same name, ie, no binding.setVariable('i', i).

Code Block
int i= 0
java('jdk1.5.0_07'){ System.out.println i; class ... ... ... }

Simplify the Antlr lexer/parser

Many existing syntactic sugars could be re-implemented as macros in a standard macro library.
This might simplify the Antlr lexer/parser, enabling better maintenance of and extensions to it.

Eg, properties where:

Code Block
String reading= 'OK

expands to:

Code Block
private String reading= 'OK'
public String getReading(){ this.xxxx }
public void setReading( String s ){ this.xxxx= s }

Other examples:

  • for( i in ... ) expanding to code using iterator
  • shorthand notation for invoking method with closure/s at last parameter/s