Logic Variables

Migration

The dedicated $IF{}/$SW{}/$CO{}/$PM{}/$NE{}/$UC{}/$LC{} variable classes described in earlier versions of this page (IfVar, SwitchVar, CoalesceVar, PatternMatchVar, NotEmptyVar, UpperCaseVar, LowerCaseVar) were removed in the 10.0.0 cycle. They were replaced by a unified #{name(args...)} function-call syntax backed by org.apache.juneau.commons.svl.functions.ConditionalFunctions (if/switch/coalesce/notEmpty) and org.apache.juneau.commons.svl.functions.StringFunctions (upper/lower). See Simple Variable Language for the full, current function catalog and syntax — this page shows the config-file equivalents of the old $IF/$SW/$CO/$PM examples using the current syntax.

Config files can use the #{...} function-call syntax anywhere a $Var{...} variable is valid, including nested inside other variables such as $S{...} (system property lookup).

The #{if(cond,then,else)} function can be used for simple if/else logic. Unlike the old $IF{} variable, the else argument is required (pass an empty string if no "else" value is needed):

# Value set to 'foo' if myBooleanProperty is true, empty otherwise.

key1 = #{if($S{myBooleanProperty}, foo, "")}

# Value set to 'foo' if myBooleanProperty is true, 'bar' if false.

key2 = #{if($S{myBooleanProperty}, foo, bar)}

# Value set to key1 value if myBooleanProperty is true, key2 value if false.

key3 = #{if($S{myBooleanProperty}, $C{key1}, $C{key2})}

The #{switch(...)} function can be used for switch blocks based on pattern matching. Arguments are flat and comma-delimited: value, pattern1, result1, pattern2, result2, ..., default. Patterns support */? glob wildcards (matched against the whole value):

# Shell command depends on the OS

shellCommand = #{switch(#{lower($S{os.name})}, *win*, bat, linux, bash, sh)}

The #{coalesce(...)} function can be used for coalescing of values (finding the first non-null/empty match):

# Debug flag can be enabled by system property or environment variable.

debug = #{coalesce($S{debug}, $E{DEBUG}, false)}

The #{match(s,regex)} function is the direct replacement for the old $PM{arg,pattern} pattern-match variable, returning "true"/"false":

# Debug flag can be enabled by system property or environment variable.

isWindows = #{match(#{lower($S{os.name})}, .*win.*)}