Jeff Winkler wrote:
> I've come up with a trigraph idiom, am curious if it's been done before
> (probably). I like to use trigraphs occasionally.
>
> Scenario: I'm doing an RSS->Javascript conversion for our intranet. I'd
> like to use different CSS class if a post is new. Code:
>
> hoursOld=abs(time.time()-time.mktime(i.modified_parsed))/3600
> cssClass=['rssLink','rssLinkNew'][hoursOld<12]
> entry='<a href="%s" class="%s" target="detail">%s</a>' %
> (cssClass,i['link'],i['title'])
>
> So, ['rssLink','rssLinkNew'] is index by boolean value- False:0, or
> True:1.
>
> I realize many will find this hideous, but 3 lines of code to do
> something simple seems equally bad. Thoughts? Is there a better way?
The need for ternary expressions seems to center around presentation to
humans. I find myself using such expressions frequently in presentation
templates or in code that prepares information for templates. You're
using it the same way.
I always write it this way:
condition and truecase or falsecase
This works as long as truecase evaluates as a true value. (If it
doesn't, the result of the expression is falsecase.) So I would write
the cssClass assignment like this:
cssClass = (hoursOld < 12) and 'rssLinkNew' or 'rssLink'
The C equivalent is more readable, but this is close enough. It's the
same trick people use in shell scripts.
Shane
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