You can beta-test the incoming packages/namespaces feature
Preprocessing
Some minor preprocessing capabilities are included in PlantUML, and available for all diagrams.
Those functionalities are very similar to the C language preprocessor, except that the special character # has been changed to the exclamation mark !.
Migration notes
The actual preprocessor is an update from some legacy preprocessor.
Even if some legacy features are still supported with the actual preprocessor, you should not use them any more (they might be removed in some long term future).
- You should not use
!defineand!definelonganymore. Use!functionand variable definition instead.!defineshould be replaced by return function and!definelongshould be replaced by void function. !includenow allows multiple inclusions : you don't have to use!include_manyanymore!includenow accepts a URL, so you don't need!includeurl- Some features (like
%date%) have been replaced by builtin functions (for example%date()) - When calling a legacy
!definelongmacro with no arguments, you do have to use parenthesis. You have to usemy_own_definelong()becausemy_own_definelongwithout parenthesis is not recognized by the new preprocessor.
Please contact us if you have any issues.
Variable definition
Although this is not mandatory, we highly suggest that variable names start with a $. There are two types of data:
- Integer number
- String - these must be surrounded by single quote or double quote.
Variables created outside function are global, that is you can access them from everywhere (including from functions). You can emphasize this by using the optional global keyword when defining a variable.
@startuml
!$ab = "foo1"
!$cd = "foo2"
!global $ef = $ab + $cd
Alice -> Bob : $ab
Alice -> Bob : $cd
Alice -> Bob : $ef
@enduml
Conditions
- You can use expression in condition.
- else is also implemented
@startuml
!$a = 10
!$ijk = "foo"
Alice -> Bob : A
!if ($ijk == "foo") && ($a+10>=4)
Alice -> Bob : yes
!else
Alice -> Bob : This should not appear
!endif
Alice -> Bob : B
@enduml
Void function
- Function names must start with a
$ - Argument names must start with a
$ - Void functions can call other void functions
Example:
@startuml
!function msg($source, $destination)
$source --> $destination
!endfunction
!function init_class($name)
class $name {
$addCommonMethod()
}
!endfunction
!function $addCommonMethod()
toString()
hashCode()
!endfunction
init_class("foo1")
init_class("foo2")
msg("foo1", "foo2")
@enduml
Variables defined in functions are local. It means that the variable is destroyed when the function ends.
Return function
A return function does not output any text. It just define a function that you can call:
- directly in variable definition or in diagram text
- from other return function
- from other void function
- Function name should start by a
$ - Argument names should start by a
$
@startuml
!function $double($a)
!return $a + $a
!endfunction
Alice -> Bob : The double of 3 is $double(3)
@enduml
It is possible to shorten simple function definition in one line:
@startuml
!function $double($a) return $a + $a
Alice -> Bob : The double of 3 is $double(3)
Alice -> Bob : $double("This work also for strings.")
@enduml
As in void function, variable are local by default (they are destroyed when the function is exited). However, you can access to global variables from function. However, you can use the local keyword to create a local variable if ever a global variable exists with the same name.
@startuml
!function $dummy()
!local $ijk = "local"
Alice -> Bob : $ijk
!endfunction
!global $ijk = "foo"
Alice -> Bob : $ijk
$dummy()
Alice -> Bob : $ijk
@enduml
Default argument value
In both return and void functions, you can define default values for arguments.
@startuml
!function $inc($value, $step=1)
!return $value + $step
!endfunction
Alice -> Bob : Just one more $inc(3)
Alice -> Bob : Add two to three : $inc(3, 2)
@enduml
Only arguments at the end of the parameter list can have default values.
@startuml
!function defaulttest($x, $y="DefaultY", $z="DefaultZ")
note over Alice
x = $x
y = $y
z = $z
end note
!endfunction
defaulttest(1, 2, 3)
defaulttest(1, 2)
defaulttest(1)
@enduml
Unquoted function
By default, you have to put quotes when you call a function. It is possible to use the unquoted keyword to indicate that a function does not require quotes for its arguments.
@startuml
!unquoted function id($text1, $text2="FOO") return $text1 + $text2
alice -> bob : id(aa)
alice -> bob : id(ab,cd)
@enduml
Including files or URL
Use the !include directive to include file in your diagram. Using URL, you can also include file from Internet/Intranet.
Imagine you have the very same class that appears in many diagrams. Instead of duplicating the description of this class, you can define a file that contains the description.
@startuml
!include List.iuml
List <|.. ArrayList
@enduml
File List.iuml
interface List
List : int size()
List : void clear()
The file List.iuml can be included in many diagrams, and any modification in this file will change all diagrams that include it.
You can also put several @startuml/@enduml text block in an included file and then specify which block you want to include adding !0 where 0 is the block number. The !0 notation denotes the first diagram.
For example, if you use !include foo.txt!1, the second @startuml/@enduml block within foo.txt will be included.
You can also put an id to some @startuml/@enduml text block in an included file using @startuml(id=MY_OWN_ID) syntax and then include the block adding !MY_OWN_ID when including the file, so using something like !include foo.txt!MY_OWN_ID.
By default, a file can only be included once. You can use !include_many instead of !include if you want to include some file several times. Note that there is also a !include_once directive that raises an error if a file is included several times.
Including Subpart
You can also use !startsub NAME and !endsub to indicate sections of text to include from other files using !includesub. For example:
file1.puml:
@startuml
A -> A : stuff1
!startsub BASIC
B -> B : stuff2
!endsub
C -> C : stuff3
!startsub BASIC
D -> D : stuff4
!endsub
@enduml
file1.puml would be rendered exactly as if it were:
@startuml
A -> A : stuff1
B -> B : stuff2
C -> C : stuff3
D -> D : stuff4
@enduml
However, this would also allow you to have another file2.puml like this:
file2.puml
@startuml
title this contains only B and D
!includesub file1.puml!BASIC
@enduml
This file would be rendered exactly as if:
@startuml
title this contains only B and D
B -> B : stuff2
D -> D : stuff4
@enduml
Builtin functions
Some functions are defined by default. Their name starts by %
| Name | Description | Example | Return |
%strlen | Calculate the length of a String | %strlen("foo") | 3 in the example |
%substr | Extract a substring. Takes 2 or 3 arguments | %substr("abcdef", 3, 2) | "de" in the example |
%strpos | Search a substring in a string | %strpos("abcdef", "ef") | 4 (position of ef) |
%intval | Convert a String to Int | %intval("42") | 42 |
%file_exists | Check if a file exists on the local filesystem | %file_exists("c:/foo/dummy.txt") | true if the file exists |
%function_exists | Check if a function exists | %function_exists("$some_function") | true if the function has been defined |
%variable_exists | Check if a variable exists | %variable_exists("$my_variable") | true if the variable has been defined exists |
%set_variable_value | Set a global variable | %set_variable_value("$my_variable", "some_value") | An empty string |
%get_variable_value | Retrieve some variable value | %get_variable_value("$my_variable") | the value of the variable |
%getenv | Retrieve environment variable value | %getenv("OS") | The value of OS variable |
%dirpath | Retrieve current dirpath | %dirpath() | Current path |
%filename | Retrieve current filename | %filename() | Current filename |
%date | Retrieve current date. You can provide an optional format for the date | %date("yyyy.MM.dd at HH:mm") | Current date |
%true | Return always true | %true() | true |
%false | Return always false | %false() | false |
%not | Return the logical negation of an expression | %not(2+2==4) | false in that example |
Logging
You can use !log to add some log output when generating the diagram. This has no impact at all on the diagram itself. However, those logs are printed in the command line's output stream. This could be useful for debug purpose.
@startuml
!function bold($text)
!$result = "<b>"+ $text +"</b>"
!log Calling bold function with $text. The result is $result
!return $result
!endfunction
Alice -> Bob : This is bold("bold")
Alice -> Bob : This is bold("a second call")
@enduml
Memory dump
You can use !memory_dump to dump the full content of the memory when generating the diagram. An optional string can be put after !memory_dump. This has no impact at all on the diagram itself. This could be useful for debug purpose.
@startuml
!function $inc($string)
!$val = %intval($string)
!log value is $val
!dump_memory
!return $val+1
!endfunction
Alice -> Bob : 4 $inc("3")
!unused = "foo"
!dump_memory EOF
@enduml
Assertion
You can put assertion in your diagram.
@startuml
Alice -> Bob : Hello
!assert %strpos("abcdef", "cd")==3 : "This always fail"
@enduml
Building custom library
It's possible to package a set of included files into a single .zip or .jar archive. This single zip/jar can then be imported into your diagram using !import directive.
Once the library has been imported, you can !include file from this single zip/jar.
Example:
@startuml
!import /path/to/customLibrary.zip
' This just adds "customLibrary.zip" in the search path
!include myFolder/myFile.iuml
' Assuming that myFolder/myFile.iuml is located somewhere
' either inside "customLibrary.zip" or on the local filesystem
...
Search path
You can specify the java property plantuml.include.path in the command line.
For example:
java -Dplantuml.include.path="c:/mydir" -jar plantuml.jar atest1.txt
Note the this -D option has to put before the -jar option. -D options after the -jar option will be used to define constants within plantuml preprocessor.
Argument concatenation
It is possible to append text to a macro argument using the ## syntax.
@startuml
!unquoted function COMP_TEXTGENCOMP(name)
[name] << Comp >>
interface Ifc << IfcType >> AS name##Ifc
name##Ifc - [name]
!endfunction
COMP_TEXTGENCOMP(dummy)
@enduml
Dynamic function invocation
You can dynamically invoke a void function using the special %invoke_void_func() void function. This function takes as first argument the name of the actual void function to be called. The following argument are copied to the called function.
For example, you can have:
@startuml
!function $go()
Bob -> Alice : hello
!endfunction
!$wrapper = "$go"
%invoke_void_func($wrapper)
@enduml
For return functions, you can use the corresponding special function %call_user_func() :
@startuml
!function bold($text)
!return "<b>"+ $text +"</b>"
!endfunction
Alice -> Bob : %call_user_func("bold", "Hello") there
@enduml
