Re: [Kidbasic-devel] Fwd: File access?

[Ferry H. <fer...@gm...>]

All done and committed to the repository (rev 134). We now have 4 file
operations:

- int open(string name, string mode)
  - mode can be one of "read" or "write", defaulting to "read".

- string read()
  - read one token from the file

- int write(string token)
  - write one token to the file

- int close()
  - close the file

Cheers

/Ferry


On 11/17/06, Ian Larsen <dr...@gm...> wrote:
> Let's start with those four, and see if we get requests for others.
>
> We can probably just use open, read, write, and close, instead of
> prepending an "f," since I don't forsee implementing READ and DATA in
> basic256.
>
> -Ian
>
>
>
> On 11/16/06, Ferry Hendrikx <fer...@gm...> wrote:
> > I agree, keeping it simple is best.
> >
> > We therefore have at least 4 new functions:
> >
> >   error = fopen( filename )
> >   - open the file (for read and write? or separate them out?)
> >   - return simple true or false
> >
> >   token = fread()
> >   - return the next token in the file
> >   - ignore line breaks?
> >
> >   fwrite( token )
> >   - write the token to the end of the file
> >
> >   fclose()
> >   - close the file
> >
> > Are these 4 enough or do we need any further functions?
> >
> > For example:
> >
> >   feof  ??
> >   - way to tell when we've reached the end of the file
> >
> >   fseek  ??
> >   - seek into the file
> >
> > Cheers
> >
> > /Ferry
> >
> >
> > On 11/17/06, Ian Larsen <dr...@gm...> wrote:
> >
> > > I think supporting one open file (at a time) would be plenty for our
> > > purposes, and would make implementation a bit easier.
> > >
> > > Instead of reading characters though, I think the default function of
> > > a file read command should be to emulate the input statement, and read
> > > entire tokens.  That way a kid could type in a file:
> > >
> > > 1  aString  2.23  -3  10
> > > 11  24  Ian  34
> > >
> > > and calling read would return 1, then "aString", and so forth.
> > > We could have the data type default to string for simplicity, counting
> > > on the programmer to change it to the type he wants with int(), for
> > > example, or we could attempt to decide what the type is based on the
> > > token.
> > >
> > > My inclination is to return strings only, to keep things simple and predictable.
> > >
> > > -Ian
> > >
> > >
> > >
> > > On 11/16/06, Ferry Hendrikx <fer...@gm...> wrote:
> > > > I definitely agree that we want to avoid the classic basic approach.
> > > >
> > > > The FOPEN (and others) approach is reasonable and we should probably
> > > > be working at the character level, as dealing with UTF-8 etc would be
> > > > a real pain...
> > > >
> > > > We could take a C-like approach and have a gets(number) function? e.g.
> > > > returns <number> characters in a string from the currently open file
> > > > (until end of line?)
> > > >
> > > > Hmm.. also, do we want to support one open file or more than one?
> > > >
> > > > Cheers
> > > >
> > > > /Ferry
> > > >
> > > >
> > > > On 11/17/06, Ian Larsen <dr...@gm...> wrote:
> > > > > Actually, I haven't given it much thought, but you're right, it would
> > > > > be good to have that.
> > > > >
> > > > > We could have an FOPEN, FREAD, and FWRITE command.  I'm just unsure of
> > > > > whether they should work at the byte or character level.
> > > > >
> > > > > What I usually do is write an example program or tutorial first, and
> > > > > then code the commands.  It helps to focus on what is actually
> > > > > necessary to teach kids.
> > > > >
> > > > > Traditionally BASIC used READ and DATA statements for data input, but
> > > > > personally I was never crazy about that approach, most importantly
> > > > > because I think data should be a separate entity from the program that
> > > > > reads/alters it.
> > > > >
> > > > > The approach that LISP takes for file input is nice.  You can use the
> > > > > lisp read command on an open file to read a token, or read-line to
> > > > > read a line.  There's also read-char and read-byte.  This might be the
> > > > > best way to handle it, so kids can have a text file of data separated
> > > > > by white space and just read each token in one at a time.
> > > > >
> > > > > -Ian
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > On 11/16/06, Ferry Hendrikx <fer...@gm...> wrote:
> > > > > > Has anyone given any thought to file access? It would be useful to be
> > > > > > able to open, read and write text files...
> > > > > >
> > > > > > Cheers
> > > > > >
> > > > > > /Ferry
> > > > > >
> > > >
> >
>