Hi Shao, On Thu, Mar 18, 2010 at 4:51 AM, Miller, Shao <[email protected]>wrote:
> Good day to All, > [snip] > > 'if <condition> <command>' : Stefan's fine implementation will execute > <command> is <condition> is a non-zero unsigned integer. Although its > behaviour can already be mimicked somewhat with some of the ugliest > recursive-variable-expansion business you've ever seen in a gPXE script, > users might be more familiar with 'if' from other scripting/programming > languages. > I think it would be nice to have at least equal and not-equal operators in <condition>, to check variable values. > > ': <label>' : This defines a "point-of-interest" in a script for jumping > to with 'goto'. Regardless of implementation, can we agree on this > form/format? > > Stefan and I worked through some examples of implementing loops and an > if-else construct where we realized that a "deferred execution" of > "routine bodies" headed by ':' was not as usable as the case where > "where they appear, there shall they be executed." I had an idea that > we might gain a reduced code-size cost with the constraint that one can > only 'goto' a "routine" which has already been passed by the parser. To > do this, I tried "deferred execution" of such routines. This proved > difficult to express an if-else construct with. A recent patch I've > submitted does not have this constraint and actually costs less code > than that strategy took anyway. > So does 'deferred execution' mean stopping code execution till the label is found? I found it a bit difficult to follow the terms yesterday. > [snip] > Regards, Lynus
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