Velocity Language Cheat Sheet

CheatSheet.vm

## ----------------------------------------------------------------------
## Telosys Template : Velocity Cheat Sheet
## ----------------------------------------------------------------------
#*
 Multi-lines comment
*#
#[[
Unparsed block (all this block will be rendered as is)
$undefined
#set($i = 50)
#foobar #zzz(ee)
#include("foo.txt")
]]#

## ----------------------------------------------------------------------
## SET
## ----------------------------------------------------------------------
#set($i = 50)
 i value : $i 
#set($f = 12.34)
 f value : $f
#set($b = true)
 b value : $b
#set($s = "abc")
 s value : $s
#set($s = "abc $i")## 'i' variable is replaced by its value
 s value : $s
#set($s = 'abc $i')## no variable substitution
 s value : $s
#set($s = 
'line 1 $a
line 2 $b
line 3 $c' )## 3 lines
 s lines : 
$s
## #set( $v = null ) ## invalid syntax
## --- Arithmetic operators
#set($x = 12)
#set($y = 4)
#set ( $r = $x + $y + 1 ) r : $r
#set ( $r = $x - $y     ) r : $r
#set ( $r = $x * $y     ) r : $r
#set ( $r = $x / $x     ) r : $r
#set ( $r = $x % 5      ) r : $r

## ----------------------------------------------------------------------
## IF / ELSE / ELSEIF
## ----------------------------------------------------------------------
#if ( $b )
 b is true
#else
 b is false
#end

 b is #if( $b )TRUE#{else}FALSE#{end}, yes it is!

#set($v = 2)
#if ( $v == 1 ) 
 v equals 1 
#elseif ( $v == 2 ) 
 v equals 2 
#else 
 v other 
#end 

#set($s = "#if( $b )TRUE#{else}FALSE#{end}" )
s : $s ## s : "TRUE"

## --- Comparison operators and logical operators
#set($x = 12.34) #set ($y = 56.78 ) x : $x, y : $y
#if ( $x == $y )#end
#if ( $x eq $y )#end
#if ( $x != $y )#end
#if ( $x ne $y )#end
#if ( $x >  $y )#end
#if ( $x <  $y )#end
#if ( $x <= $y )#end
#if ( ! ($x == $y) )#end
#if ( not ($x == $y) )#end
#if ( $x == $y && $x > 10 )#end
#if ( $x == $y || $x > 10 )#end
#if ( $x == $y || ( $x > 10 && $s < 200 ) )#end
#set($list = ["a","b","c"])
#if ( $list.isEmpty() )
list is empty
#else
list is not empty
#end

## ----------------------------------------------------------------------
## FOREACH
## ----------------------------------------------------------------------
#foreach( $item in [1..4] )
 . ${item} 
   $foreach.class.name
   count   : $foreach.count   / index     : $foreach.index 
   hasNext : $foreach.hasNext / hasNext() : $foreach.hasNext()
   first   : $foreach.first   / isFirst() : $foreach.isFirst() 
   last    : $foreach.last    / isLast()  : $foreach.isLast()
#set($n = $foreach.count )## global variable
#end
 n (after foreach ) : $n

## ----------------------------------------------------------------------
## MACRO
## ----------------------------------------------------------------------
#macro( add $a1 $a2 )
#set ( $r = $a1 + $a2 )
 Add $a1 + $a2 : result is $r 
#end
## call macro :
#add( 20, 3 )

## ----------------------------------------------------------------------
## DEFINE
## ----------------------------------------------------------------------
#define( $header )
// My super project 
// Copyright 2018
// Author $author
#end
#set( $author = "John" )
$header

## ----------------------------------------------------------------------
## EVALUATE
## ----------------------------------------------------------------------
## evaluate the instruction string 
#evaluate('#set($z=12)') 
z : $z

## init map content as string :
#set( $map = '{ "k1":"v1" , "k2":"v2"   }' ) 
map : $map
## compose instruction string :
#set( $instruction = '#set( $z = ' + $map + ' )' )  
instruction : $instruction
## evaluate instruction string :
#evaluate($instruction) 
z : $z  ## z is a map instance