Often I'll have surrounding context that I use to define something, that has
very little relevance outside of that something. For instance:
let placeholder = "first $delim second $delim third".split("$delim",2)
let first = placeholder[0]
let second = placeholder[1]
let third = placeholder[2]
I will want to use first, second and third elsewhere in my program, but
placeholder only exists to create them, and it claims the name "placeholder" so
the next time I do something like this, I have to use "placeholder2" or
something, and just manually avoid name conflicts.
It's tempting to say the solution is to return a tuple, but even that requires
a dummy name
proc stillaplaceholder(): tuple[str,str,str] =
const placeholder = staticRead("somefile").split("$delim",2)
return (placeholder[0],placeholder[1],placeholder[2])
let (first,second,third) = stillaplaceholder()
And often times I want to define a procedure, which isn't exactly the same as
returning a procedure.
var select = prepare("SELECT info FROM thingy WHERE id = ?1")
var insert = prepare("INSERT INTO thingy DEFAULT VALUES")
proc createThingy(id: int64): something =
result = select.gofind(id)
if not result:
insert.inject()
result = last_row_id_thing()
Yeah, sqlite is great, I know. But I don't want to pollute my namespace with
"select" and "insert", and it seems silly to make a separate module for every
table in the database that acts like this. But I can't put it in a block,
otherwise createThingy will go out of scope! I thought about using a template...
template createcreateThingy(name: untyped, select: string, insert: string) =
var a = prepare(select)
var b = prepare(insert)
proc `name`(id: int64): something =
...
but then I end up with this ridiculous bit of code:
createcreateThingy(createThingy,"SELECT info FROM thingy WHERE id =
?1","INSERT INTO thingy DEFAULT VALUES")
I'm really not trying to automate creation of the code _inside_ the procedure.
I'm just trying to hide the "select" and "insert" variables. Sure I could
prepare them every time the function is called, or make some sort of a cache to
look up previously prepared statements, but it's nicer to just use a
surrounding context, and have nim just know which variables are which.
Is there an elegant solution to this? Or am I just being too picky, and using
stuff like placeholder2 is a perfectly good idea?
