clarification needed: assigning function value and forward reference

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  • Posted by _tom (admin) Apr 09, 2010
  • 1292 views

This first demo shows that it is possible use a routine that is declared after the request to use it: 

include std/console.e 
 
display("#1 test forward referencing of routines" ) 
 
one() 
 
--two() 
? two() 
 
procedure one() 
    display("this is one") 
end procedure 
 
function two() 
    display("this is two") 
    return "" 
end function 
 
two() 
 
--------------------------------------------- 
 
-- executes with the display... 
 
-- #1 test forward referencing of routines 
-- this is one 
-- this is two 
-- {} 
-- this is two
The the odd thing is that the first time two() is used it must assign a value to something. The second time two() is used, a value does not have to be assigned. 

include std/console.e 
 
display("#2 test forward referencing of routines" ) 
 
 
one() 
 
two() 
 
 
procedure one() 
    display("this is one") 
end procedure 
 
function two() 
    display("this is two") 
    return "" 
end function 
 
two() 
 
----------------------------------------------- 
 
-- crashes with the message... 
 
-- scope2.ex:8 
-- <0068>:: expected a procedure, not a function 
-- two() 
--    ^

How do I understand (and document) this activity?

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