New line in table built with variables broken [from 1.2020.20]

Question

Hello PlantUML team,

Here is an issue reported (by Jesper) on:

• https://forum.plantuml.net/10265/new-line-in-table-built-with-variables-is-ignored?show=12478#c12478

with a broken example from 1.2020.20:

[See on PlantUML server]

Thanks for your support,
Regards,
Th.

Comments

Not good. It destroyed a lot of existing code.

Answer 1

We have added a function %newline() that output a new line :-)

So now you should use :

@startuml
!global $table = "|= Field1 |= Field 2 |"
!procedure $row($value1, $value2)
%set_variable_value("$table", %get_variable_value("$table") + %newline() + "| " + $value1 + " | " + $value2 + " |")
!endfunction

$row("1", "2")
$row("3", "4")

rectangle r [
<i>on rectangle:
$table
]
@enduml

Comments

That is good.... but this new feature is not so so good...

That broke also all the new line on multi-line label!

Here are some other similar issue:

1/ Minimal example

@startuml
node n [
aaa\n
bbb
]
@enduml

2/ Example with procedure...

Where for example, we does not manage the argument value directly... and the presence of newline on the argument...

@startuml
!procedure $foo($as, $label)
  node $as [
    ----
    The label is:
    <b>$label
    ----
    other data
  ]
!endprocedure

$foo("a", "<color:red>aaa\nbbb")
$foo("b", "label without newline")
@enduml

---

See also other broken examples:

• https://plantuml.com/en/preprocessing#f6abbca02be31ee1
• [with "This description is\non several lines""]

I understand the difficulty about newline management... between inline and multi-line... but...

→ What are changes since last version ?

Thanks for your support...
Regards,
Th.

---

I understand the difficulty about newline management... between inline and multi-line... but...

Yes, it's a mess :-)

In hindsight, it was a bad idea to interpret "\n" as "newline". We did so because it was the usual way but it has become an issue when users want to actually print \n.

So, as advice, do not use it too much : it's probably going to be removed in the future.

We are still looking for a replacement for "\n" as "newline". What about <+newline> or <U+newline> or <U+NL> ? This is completely non standard, but this way, there will be not confusion between PlantUML language and all other programming language.

We are also thinking about implementing triple quote string.Do you thing it's a good idea ?

---

Hello PlantUML,

Thanks for your answer.

In fact, the main issue is that when we does not know on which context a string or a variable will be used, as:

@startuml
!$var=" aaa \n bbb \n <u:blue>ccc \n <color:green>ddd <U+000A> eee"

node "$var" as a

node b [
$var
on multi-line context
]

node c [
<code>
$var
</code>
]
@enduml

[See on PlantUML server]

For the question:

What about <+newline> or <U+newline> or <U+NL> ?

Why not use ... the normal Unicode  <U+000A> ('LINE FEED (LF)' (U+000A))
But on the example, the value is not evaluate. Why ?

Then implementing:

• triple quote string (like Python)
• or here-doc (like major language)
• or literal strings (like Lua)

are perhaps a good news... in order to suppress the evaluation of  '\n'...
And I think that is similar question/issue on ‘JSON’ side (where ‘\n’ is an escaped value for newline, and must be evaluate [or not]...)!

See also discussion on the same subject:

• https://forum.plantuml.net/11343/activity-diagram-multi-line-and-n-management
• https://forum.plantuml.net/11350/deployment-diagram-creole-table-does-not-work
• https://forum.plantuml.net/8952/table-within-class
• https://forum.plantuml.net/4825/can-n-t-etc-be-handled-within-note-texts

If that can open an open discussion,
Regards,
Th.

---

Why not just saying that '\' is an escape character, so if you write '\n' the n is escaped and interpreted as a new line:

foo\nbar is always rendered as

foo

bar

and if you do not want it to be interpreted escape the backslash with a second backslash '\\n'

foo\\nbar is always rendered as

foo\nbar

---

Escape the backslash with another backslash if you do not want it to be read as such.

---

If the new line in a table built with variables appears broken, ensure that the variables containing the table content are properly formatted with appropriate line breaks or HTML tags. Verify that the table structure and formatting are correct to ensure the desired line breaks are displayed correctly within the table.

Answer 2

In actuality, the biggest problem arises when we are unsure of the context in which a string or variable will be utilised.

Comments

On the "JSON" side, I believe there is a related query or problem (where "n" is an escaped value for newline and must be evaluated [or not]).