<div dir="ltr"><div><div><div><div><div><div><div>When I see what Robby is forced to write when following the Style:<br><a href="https://github.com/plt/racket/commit/09d636c54573522449a6591c805b38f72b6f7da8#L4R963">https://github.com/plt/racket/commit/09d636c54573522449a6591c805b38f72b6f7da8#L4R963</a><br>
</div><br>I cannot help but think that something is wrong somewhere (it may not be the Style, and in case it wasn't clear I'm certainly not criticizing Robby's code).<br></div><div></div>Using `let' and `and' instead, although<span style="font-family:courier new,monospace"><span style="font-family:arial,helvetica,sans-serif"> being a bit better since it avoids all the [else #f], is not that big an improvement:</span><br>
<br>(define (get-x-spot char-width)<br> (and<br> char-width <br> (let ([dc (get-dc)])<br> (and<br> dc<br> (let ([style (or (send (get-style-list) find-named-style "Standard")<br> (send (get-style-list) find-named-style "Basic"))])<br>
(and<br> style<br> (let*-values ([(fnt) (send style get-font)]<br> [(xw _1 _2 _3) (send dc get-text-extent "x" fnt)])<br> (+ left-padding (* xw char-width)))))))))</span><br>
<br><br></div>Actually I think here the right thing to do might be to allow for internal definitions inside `and':<br><br><span style="font-family:courier new,monospace">(define (get-x-spot char-width)<br> (and char-width<br>
(define dc (get-dc))<br> dc<br> (define style (or (send (get-style-list) find-named-style "Standard")<br> (send (get-style-list) find-named-style "Basic")))<br>
style<br> (define fnt (send style get-font))<br> (define-values (xw _1 _2 _3) (send dc get-text-extent "x" fnt))<br> (+ left-padding (* xw char-width))))<br></span><br><br></div>Isn't it *much* more readable? (shorter, avoid rightward drift, less parens, vertical alignment)<br>
<br></div><div>Since it's not the first time I find the need for such internal definitions in `and', maybe this is something to consider for future addition to Racket? Or have some people already identified some problems with this idea?<br>
</div><div><br></div>I've played a bit with it if you want to try by your own:<br><a href="https://gist.github.com/Metaxal/5758394">https://gist.github.com/Metaxal/5758394</a><br><br></div>(not sure I got it all good with syntax-parse though)<br>
<br></div>Laurent<br><div><div><br></div></div></div>