Rebol: why get-access-modifier is called twice whereas It should be called only once - rebol

Question

When typing in rebol console
do read http://askcodegeneration.com/csharp/simple-class/
I get get-access-modifier called twice:
Access modifier:
1. private: member can be accessed only by code in the same class
2. protected: member can be accessed only by code in the same class or in a derived class
3. internal: member can be accessed only by code in the same assembly
4. public: member can be accessed by code in the same assembly or another assembly that references it choice (by default 1):
Access modifier:
1. private: member can be accessed only by code in the same class
2. protected: member can be accessed only by code in the same class or in a derived class
3. internal: member can be accessed only by code in the same assembly
4. public: member can be accessed by code in the same assembly or another assembly that references it choice (by default 1):
Whereas it is only mentioned once in the source code:
append fields-template-output form reduce [
(to-word get-access-modifier) field-layout
]
I really can't see why, can you ?
Original code here (Internet Archive)

Answer 1

Yes. There is only one call to it, but it's inside of a foreach. Your default is two fields, so you get asked twice. Enter more, you'll get asked more.
While you could (and probably should) do the obvious thing of saving it in a variable, Rebol has other ways. For instance you could compose the block of code:
foreach field-layout fields-layout COMPOSE/DEEP [
append fields-template-output " "
append fields-template-output form reduce [
to-word (get-access-modifier) field-layout
]
append fields-template-output ";"
append fields-template-output newline
]
The composition runs once, looks deep for the parentheses in the block, and evaluates the code. (Kind of how parse does when it sees parentheses). The rest is left alone. So the block with the substitutions done is what's passed into FOREACH to run the loop.
Just a nuance of how you could have a call that appears to be inside a loop and yet is executed only once. I wouldn't suggest using it for something like this.
What I would suggest is studying making things less redundant in your code, by learning some more Rebol primitives like REJOIN...which builds a series out of a block. The series type will match whatever the first type it sees is (or a string if the first element is not a series):
modifier: get-access-modifier ;-- called only once, stored in variable
foreach field-layout fields-layout [
append fields-template-output rejoin [
" "
(to-string modifier)
field-layout
";"
newline
]
]

Answer 2

To solve the problem I have used static var to detect that it is executed only once (thanks to Sunanda tips is it possible to have static variable inside a rebol function? ).
ask-params: function [config-file [file!] default-class-name default-fields] [
;config-file: %askcodegeneration.com/csharp/simple-class/simple-class.params.txt
either value? 'class-name [
ans: ask rejoin ["class name" " (by default " class-name ")" ": "]
if ans <> "" [class-name: ans]
][
class-name: default-class-name
ans: ask rejoin [{class name (default "} class-name {"): }]
if ans <> "" [class-name: ans]
]
either exists? it: config-file [
params-block: copy load it
][
params-block: []
]
either res: find params-block class-name [
fields: pick res 2
print [ class-name "found in" it]
][
fields: default-fields
ans: ask rejoin [{fields (by default } {"} fields {"} {): }]
if ans <> "" [fields: ans]
new-param: reduce [
mold class-name
mold fields
]
either not exists? config-file [
create-directory "askcodegeneration.com/csharp/simple-class/"
write/append config-file reform new-param
][
write/append config-file reform [newline new-param]
]
]
append ret-value: [] class-name
append ret-value fields
ret-value
]