Euphoria
Ticket #525:
constant expression not recognized as is in enum type
-
Reported by
coconut
Dec 10, 2010
try this:
enum type test a='?'-'0' end type
C:\euphoria-40\work\win32\temp>eui test.ex
c:\euphoria-40\work\win32\temp\test.ex:1
<0138>:: Syntax error - expected to see 'type' after 'end', not a number
enum type test a='?'-'0' end type
^
this is a constant expression!
Details
1. Comment by jimcbrown
Dec 10, 2010
This is not a bug. Both enum and type are being misused, although the error message could be improved.
2. Comment by mattlewis
Dec 10, 2010
The euphoria front end does not do constant folding like this currently.
3. Comment by jeremy
Dec 10, 2010
How should it be used?
4. Comment by jimcbrown
Dec 10, 2010
Type is this
type test(object a)
return integer(a) and (a >='?' and a <= '0')
end type
And enum is this
enum test
first_test = '?',
second_test,
third_test,
...
last_test_is_zero
5. Comment by DerekParnell
Dec 10, 2010
It should be used like this ...
enum type test
a = 15 -- '?'-'0'
6. Comment by DerekParnell
Dec 10, 2010
Jim, Euphoria supports enum types. This means that you can easily turn an enum set into a type.
enum type colors
blue, black, red, orange, white
function xyz( colors C)
... whatever ...
end function
xyz(blue) -- ok
xyz(100) -- fails with a type error.
7. Comment by mattlewis
Dec 10, 2010
Close, Derek, but you missed the end type:
enum type test
a = 15 -- '?'-'0'
end type
The problem raised here is not the use of enum type but the expectation of folding '?'-'0' into 15.
8. Comment by jimcbrown
Dec 10, 2010
Whoops, my mistake. Looks like this is valid after all.
9. Comment by coconut
Dec 10, 2010
This should be a bug because expression like '?'-'0' can be evaluate at parse as constant...
Please consider adding this to feature development.
10. Comment by coconut
Dec 10, 2010
previous message should
adding this feature in future development
11. Comment by jeremy
Dec 10, 2010
Converted to a feature request...
Constant Folding for enum assignments.
12. Comment by SDPringle
May 22, 2015
See: hg:euphoria/rev/4825c64e9606
changeset: 6329:4825c64e9606 branch: 4.0 parent: 6327:ab5bb430c02b user: Shawn Pringle <shawn.pringle@gmail.com> date: Sat Jan 03 16:41:46 2015 -0300 files: source/parser.e tests/t_c_enum_strings.d/control.err tests/t_c_enum_strings_sneaky.d/control.err tests/t_c_enum_strings_sneaky.e tests/t_c_fwd_enum_type.d/control.err description:
- ticket 525: enabled enum type values to be assigned any expression.
13. Comment by SDPringle
Sep 24, 2015
See: hg:euphoria/rev/b2b465335529
changeset: 6365:b2b465335529 branch: 4.0 user: Shawn David Pringle B.Sc. <shawn.pringle@gmail.com> date: Wed Sep 16 00:25:09 2015 -0300 files: tests/t_enum_expressions.e description: ticket 525: unit tests added for arbitrary enum expressions
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