macro expansion in two steps with ## does not work

Question

I think there is a problem when expanding macros into other macros which are using ##

 

Here is an example which illustrates the problem.

 

--

!definelong SEND_TO_b(from,message)

  from -> b : MYPROT:\n##message

!enddefinelong

 

!define SEND_FROM_a_TO_b(message) SEND_TO_b(a,message)

 

SEND_TO_b(a,Hello)    'Works fine

SEND_FROM_a_TO_b(Hi)  'Does not work

--

The expected behavior is that thre should be two arrows from a to b, where the first one is labled "

 

MYPROT:

Hello

 

and the second one is labled

 

MYPROT:

Hi

 

However the second arrow is instead labled

 

MYPROT:

message

 

To see that this is related to the use of ## in the macro, replace the ## with a space (which will indent the second row slightly) The second arrow will then be labled

 

MYPROT:

 Hi

 

I guess this is a bug-report, but I could not find where to report this.

MYPROT:

Hi

Answer 1

Thanks for the report, this is the right place to do bug-report.

We'll investigate this.

Note that changing macro definition fixes the issue. Don't know if this is a workaround for you.

@startuml
!define SEND_FROM_a_TO_b(message) SEND_TO_b(a,message)
!definelong SEND_TO_b(from,message)
  from -> b : MYPROT:\n##message
!enddefinelong
 
 
SEND_TO_b(a,Hello)    'Works fine
SEND_FROM_a_TO_b(Hi)  'Does not work
@enduml

Comments

Thanks! Just changing the order in which the macros are defined solved it. It is certainly a workaround that works for me. Thanks!