Newbie question, I guess.

[Alex Martelli]

"thedog" <thedog at linux.nu> wrote in message
news:3AF695A6.9E461EC5 at linux.nu...
> Newbie question, I guess.
> I have two variables direction and framenr
>
> direction = 'fw'
> framenr = 1
>
> which I want to use in the following code to navigate round in my little
> game.
    ...
> the problem is the line: frame = '%(direction)s%(framenr)simage' %vars()
>
> when using this a string is passed to frame(for example, when the up
> arrow is pressed: the string ‘fw1image’). But I don’t want a string to
> be passed to it just fw1image, because fw1image is a surface that later
> will be shown on screen.
>
> So I want to change ‘fw1image’ to fw1image, is this possible?

Yes,
    frame = eval(frame)
or
    frame = vars()[frame]
would do this.

> Or if you know any better way of accomplishing this, enlighten me.

It's probably beter to keep your "surfaces that later will be shown"
into a dictionary rather than in separate variables that are only
connected by having similar/systematic names.

E.g.: instead of having
    fw1image = animage()
    fw2image = anotherimage()
    # etc
have
    images = {}
    images['fw',1] = animage()
    images['fw',2] = anotherimage()
(or, whatever else you currently do to bind these separate
variables, do it instead to bind items in the dictionary
called images).

Now, instead of
    frame = '%(direction)s%(framenr)simage' %vars()
    frame = vars()[frame]

you can use the simpler and clearer:
    frame = images[direction, framenr]


> PS. I’m sorry if the text is confusing, but I’m very very tired.

No problem!  I hope I did understand your problems correctly.

Needs to manipulate variable names, and get the objects from
variable names that are held as strings, most often do come
from not having used a dictionary, but rather a bunch of
unrelated variables with similar systematic names, to hold
certain items -- it seems to me that this general pattern is
applicable to your case.  If it isn't, then we may need to
dig further!


Alex