[Freeciv-Dev] Re: (PR#2464) patch: restrict techs by nation

["Raimar Falke via RT" <rt@xxxxxxxxxxxxxx>]

On Tue, Jan 28, 2003 at 03:08:04PM -0800, Per I. Mathisen via RT wrote:
> 
> New patch. I've dropped my previous approach and gone for Greg's idea
> instead. Now you specify a root tech which cannot be shared, and it
> "contaminates" the rest of the tree, unless you explicitly stop it from
> doing this. There is no more mention of nations. Now, nations must specify
> root techs in init_techs.
> 
> Please read, comment and test.

>  /**************************************************************************
> +  Returns TRUE iff the given tech is ever reachable by the given player
> +  by checking tech tree limitations.
> +**************************************************************************/
> +bool tech_is_available(struct player *pplayer, Tech_Type_id id)
> +{
> +  int root = advances[id].root_req;

The test below can fail but you get a bad array access here.

> +  if (!tech_exists(id)) {
> +    return FALSE;
> +  }
> +

> +  if (root != A_NONE && root != A_LAST

tech.h only mentions A_NONE as a special value for root_req.

> +      && get_invention(pplayer, root) != TECH_KNOWN) {
> +    /* This tech requires knowledge of another tech before being 
> +     * available. Prevents sharing of untransferable techs. */
> +    return FALSE;
> +  }
> +  return TRUE;

> [advance_babylonian_bonus]
> ; This tech can be stolen by other nations, but only Babylonians can
> ; research it!

If this comment is true than this is bad. An nontransferable tech
should be nontransferable.

Also what happens if a tech gets two root techs?

        Raimar

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