Re: Buffering inputted characters

[Joel VanLaven <jvl@ocsystems.com>]

PantsMaster <dougie@drumkit.demon.co.uk> wrote:

: I am attempting to write a game in Ada 95.  I am aware that this is hardly
: the most optimal platform for building a game, but nevertheless I am giving
: it a go.  What I would like to know is how I can get a program to look for
: (keyboard) input.  It would check to see if there has been any, and carry
: out appropriate actions depending on the input.  How can this be done
: *without holding up the rest of the program?*

Text_io.get_immediate is your answer.  Note that this will also return
control characters like new-lines and such (as opposed to get).

Note that simce this is a new Ada95 feature that requires new ways of
doing things some implementations might not get it completely right :)
However, I think that new features like this have firmed up alot since
the first Ada95 compilers.

Here is A.10.7 (11-12) from the Ada95 LRM:

procedure Get_Immediate(File      : in  File_Type;
                        Item      : out Character;
                        Available : out Boolean);

procedure Get_Immediate(Item      : out Character;
                        Available : out Boolean);

f a character, either control or graphic, is available from the specified
File or the default input file, then the character is read; Available is
True and Item contains the value of this character. If a character is not
available, then Available is False and the value of Item is not
specified. Mode_Error is propagated if the mode of the file is not
In_File. End_Error is propagated if at the end of the file. The current
column, line and page numbers for the file are not affected. 


Note that there is a get_immediate without the available parameter.  This
will cause the program to await input in the same way the get procedure
will.

-- Joel VanLaven