1. Record example
Here is a small example of bookstore application that makes use of "my"
idea of records in Euphoria. This kind of syntax won't break existing code.
Record members are accesed by subscripts, the interpreter would
automatically translate member names to their appropiate subscript index.
The "of" keyword is used to limit the data types supported by a sequence
(currently it's data type "object"). Comments and suggestions are welcome.
I would really like to hear Rob's opinion on the viability of such an
enhancement.
record Author
sequence FistName
sequence MiddleName
sequence lastName
end record
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record Book
sequence ISBN
sequence Title
sequence of Author
integer Pages
integer Year
sequence Publisher
sequence Summary
atom Price
end record
sequence Books of Book
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function AddBook(record NewBook)
for i =3D 1 to length(Books)
if equal(Books[i][ISBN], NewBook[ISBN]) then
return -1
end if
end for
append(Books, NewBook)
end function
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function DeleteBook(sequence ISBN)
integer pos
pos =3D 0
for i =3D 1 to length(Books) do
if equal(Books[i][ISBN], ISBN) then
pos =3D i
end if
end for
if pos then
if pos =3D 1 and length(Books) =3D 1 then
Books =3D {}
elsif pos =3D length(Books) then
Books =3D [1..length(Books)-1]
else
Books =3D Books[1..pos-1] & Books[pos+1..length(Books)]
end if
return 1
else
return 0
end if
end function
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function GetBook(sequence ISBN)
for i =3D 1 to length(Books) do
if equal(Books[i][ISBN]), ISBN) then
return Books[i]
end if
end for
end function
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-- -- -- -- -- -- -- -- -- -- -- -- --
Author new_author
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new_author[FirstName] =3D "Charles"
new_author[MiddleName] =3D ""
new-author[LastName] =3D "Petzold
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Book new_book
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new_book[ISBN] =3D "84-481-0723-3"
new_book[Title] =3D "Programaci=A2n en Windows 95" -- It's in spanish
new_book[Auhtor] =3D {new_author}
new_book[Pages] =3D 1094
new_book[Year] =3D 1996
new_book[Publisher] =3D "McGraw Hill / Microsoft Press"
new_book[Summary] =3D "Best introductory WinAPI \n book available"
new_book[Price] =3D 49.95
Special attention requires Jacques Guy "ilumininated" suggestion about
routine id's. OO Euphoria now seems more than feasible! It's implementation
needs foward declarations, read-only fields, and a "this" kind of
reference. A a new syntax should be created:
call_proc(rec[Draw]) isn't very nice ;)
Regards,
Daniel Berstein
daber at pair.com
