Xpand Template Language - Eclipse Modeling Project: A Domain-Specific Language Toolkit - page 616

« LET expression AS varName»
. . .
« ENDLET »
Statements using the variable are nested within the block. For example, if we
wanted to use a «LET» statement for our Topic CSV filename, we could refactor
our template as shown next. When accessing «LET» or metamodel elements
within a body, simply place the name within guillemets, as in «fileName» .
« LET title + "-topics.csv" AS fileName»
« FILE fileName TOPIC_OUTLET-»
«name»,«start»,«end»
« ENDFILE »
« ENDLET »
14.1.10 ERROR
You can terminate the execution of a template by inserting an «ERROR» state-
ment. The expression will be used as the message of an XpandException ,
which is thrown if the «ERROR» is processed. Note that it's typically best to val-
idate input model elements before executing templates, so using the «ERROR»
statement is rarely required. This is the general syntax:
« ERROR expression»
This simple example reports when the passed Map class has no title set:
« DEFINE Main FOR Map»
« IF title == null || title == ''-»
« ERROR 'No title'»
« ELSE »
...
« ENDIF »
« ENDDEFINE »
14.1.11 REM
Comments can be added to templates to provide documentation using the «REM»
statement. «REM» tags cannot be nested. They follow this general syntax:
« REM »Text comment here...« ENDREM »