It Must Be Time for Tea

Wednesday October 01, 2008

Using the MH date2local function

Bill Janssen recently suggested on the MH-E developers list a different format for showing the contents of a folder. Normally MH-E just shows the month and day, e.g., 09/17, for the date. One of Bill's suggestions was that if the message is less than a day old, MH-E could show the time instead, e.g., 13:45.

I've been happy just seeing the date, but I could see how showing the time might be useful. I did have one concern, which was whether MH (which is what MH-E runs on top of) would use the message's timezone or my local timezone. I routinely get email from all over the USA, plus the United Kingdom, China, India, Australia, and Japan. To get an accurate sense of when the emails were sent--for the timestamps to be useful--I'd want to see them all in my timezone.

Unfortunately, some experimentation showed me that Bill's patch used the sender's timezone.

But poking around in the mh-format man page showed a date2local function that would convert the displayed time to my local timezone. Ah, just what I wanted.

I first tried using it in something like

%02(hour(date2local{date})):%02(min(date2local{date}))

but that produced error messages. Looking more closely at the man page showed me that date2local works by side-effect; it doesn't return an updated date string. Okay, so how do you use it? I couldn't figure it out from the man page, and Googling for date2local didn't show any usage examples.

But I did get some Google hits that reminded me of the sample format files that typically ship with MH. After staring at them for a bit, I tried

%(void(date2local{date}))%02(hour{date}):%02(min{date})

and that worked.